Medicinal Plants PDF

Medicinal Plants Faculty of Pharmacy South Valley University Medicinal Plants First Year Pharm D Students Prepared by Staff Members of Pharmacognosy Department Faculty of Pharmacy South Valley Univ...

Medicinal Plants Faculty of Pharmacy South Valley University Medicinal Plants First Year Pharm D Students Prepared by Staff Members of Pharmacognosy Department Faculty of Pharmacy South Valley University 1  Medicinal Plants Pharmacognosy Definition: Pharmacognosy is the science that mainly concerned with the study of the natural substances having medicinal values. Whether these substances are from plant, animal, and mineral organs. Functions of Pharmacognogist The chief functions of the pharmacognogist are: 1. Identification of the source of the material forming a drug. 2. Determination of the morphological characters of drug. 3. Identification of the potency of the drug. 4. Planning and device methods of cultivation of the medicinal plants yielding these drugs. 5.Identification of the constituents of drugs and investigation of their chemical nature and reactions. Classification of drugs for study 1. Alphabetical; using either Latin or English names 2. Taxonomic; the drugs are arranged according to phyla, orders, families, genera, and species. 3. Morphological; as leaves, flowers, seeds, fruits, bark, roots, rhizomes. 4. Chemical; as volatile oils, alkaloids, glycosides, flavonoids. 5. Pharmacological action; as anti-cough, carminatives, antispasmodic Official and non-official drugs Official drug is listed and described in a book government as the legal authority for standards (Pharmacopoeia). The first Egyptian pharmacopoeia appeared in English in 1953 and in Arabic in 1961. 2  Medicinal Plants Plant Nomenclature binomial system, in which the first name denotes to the genus, while the second (specific) name denotes the species. In many cases the genus or species name indicates certain character of the drug as; a- Taste; Glycyrrhiza glabra, Glycys from glucose = sweet, rhize = root, referring to sweet taste of the root. Also glabrous = smooth). b- Odour; Myristica fragrans (having fragrant odour). c- Colour; Digitalis purpurea (purpurea = purple). Indigenous plants are plants grow in their native country. Cultivated plants are introduced to new locality. The cultivated or introduced plants May be: Intentional or by chance.  When the plant grows naturally without taking care of it by man; it is known as wild plant.  Plants cultivated by sowing seeds and looked after are said to be cultivated plants. Production of crude drugs 1-Cultivation Drugs may be collected from wild plants as Strophanthus, Gentian, or may be cultivated as Cannabis, Ginger, Cinnamon. The collection of drugs from wild plants has the following disadvantages: 1- Difficulty of collection owing to their distribution over unlimited areas in deserts. 2- Difficulty of identifying the proper plants because they grow associated with numerous different species. 3  Medicinal Plants 3- Difficulty of transport when far from means of transportation and from the factory. 4- Generally the collectors are unskilled or ignorant, thus causing collection of improper plants. 5- Insufficiency of supply of wild plants to meet demands of the market. 6- Continual collection may lead to a serious deficiency in supplies of many species. Cultivation of medicinal plants has the following advantages. 1.Ease of collection due to their concentration in a small, controlled area. 2.Improvement of quality by improving condition of the soil. 3.Assurance of regular and constant supplies to demands of market. 4.Control of purity. 5.Ease of transported 6.All operations; collection, drying, and storage are carried out by skilled and trained workers. 7.Cultivation is essential in the case of drugs which subjected to governmental control as Opium and Cannabis. 2- Collection Factors affecting collection of medicinal plants. Time factor; the proper time of collection is particularly important since changes in the nature and quantity of constituents varies greatly in many species. A- Time of the year 1- Rhubarb (rhizomes and roots); contain no anthraquinone derivatives in winter but contain anthranols which on the arrival of warmer weather, are converted by oxidation into anthraquinones. 4  Medicinal Plants 2- Colchicum corm; must be collected shortly in summer, usually in July when the active constituents, colchicine reaches its maximum percentage (0.4%). In autumn, the corm becomes free from the constituents and the farmers eat it, hence it becomes almost free of bitterness. 3- Most of the solanaceous drugs as Hyoscyamus muticus, contain their lowest percentage of active constituents in winter, and highest percentage at end of early summer which is the suitable time of collection. B- The time of day Collection of Digitalis and Salix. In these two drugs the active glycosides split during the night liberating the sugar, but the aglycone recombines with sugar during daytime when the plant exposed to sunlight and carbon assimilation take place. So, collection of leaves is preferred in the afternoon. C- The stage of maturity 1- Conium fruits; when the fruits of conium are fully grow but unripe (green), they will yield over 3% of coniine, but when ripe and mature (yellow), the alkaloid diminished rapidly in quantity (1%) of coniine. 2- Santonica flower; when the flower heads of Santonica are still unexpanded, they will yield 3% of santonin, but just as soon as the flowers mature (fully expanded), there is a rapid disappearance of the santonin which is anthelimentic bitter principle. 3- Insect flower; which is Pyrethrum flower was found experimentally when the flowers are closed; produce the highest powerful insecticidal substances. Worth nearly twice as much as that; made from the half-open of fully open flowers. 3-Preparation Cleaning: from solid particles by shaking, brushing or washing under stream of water. Garbling: removing of extraneous matter as sand, dirt. 5  Medicinal Plants Decortication: removal of outer unrequired tissues of some barks as cinnamon, rhubarb, liquorice either due to lack of active constituents or presence of unrequired constituents in these tissues. 4- Drying Purpose 1- To aid in their preservation. 2- To fix their constituents i.e. to stop hydrolytic enzymes or reactions that might alter the chemical composition of the drug. 3-To prevent the growth of micro-organisms as bacteria and fungi. 4- To facilitate milling and grinding of drug to powder. 5- To reduce weight and bulk, to facilitate packing, storage and transport. Methods of drying I- Natural drying; is the use of climatic heat, thus the drug is dried by exposure to direct sun, or spreading in the shade. Shade drying; is employed when the natural colour of the drug is desired. Sun drying; is adaptable to those drugs which are not affected by direct action of sunlight. II- Artificial drying; a-direct fire b- heated stones c- drying chambers e- vaccum drying (at low pressure, low temp.) f- freeze drying or lyophilization. lyophilization is the removal of water from the drug when present in the frozen state. Sublimes into vapors directly without passing to the liquid state. Used for extremely delicate products as vitamins, hormones. 6  Medicinal Plants 5- Packing, Storage and preservation It is the last and most important stage in the handling of crude drugs before used. Methods of controlling insects in crude drugs 1-Heat treatment 2-Cooling 3-Fumigation; By the use of various volatile insecticidal agents is satisfactory and has the advantage being non-inflammable. Carbon bisulfide and cyanide gas sometimes are used. 4- Liming; the drug is dipped in freshly prepared lime or sprinkled with quicklime to coat it with a fine powder. Adulteration Adulteration occurs when the drug is rare or when the price of a drug is normally high. The adulterant must be some material which is both cheap and available in large amount. Forms of adulteration 1- Sophistication (Intended adulteration); the addition of any material of no value as addition of wheat flour to powdered Ginger, artificial invert sugar to honey. 2- Substitution; replace the genuine drug totally by different article, substitution may occur in different ways; a- Arabian senna and dog senna to adulterate genuine Senna. Capsicum minimum fruits and chilies for Capsicum annum fruits. b- Substitution of exhausted drugs; some preparations are used in very large amount for the adulterant of drugs as, colouring matters or dyes to Saffron, methyl red to Rose petals. 7  Medicinal Plants c- Substitution of superficially similar but cheaper natural substances, usually have no relation to genuine drugs such as Clove stalks and mother Clove are often mixed with Clove. 3- Admixture; (Non intended adulteration); the addition of one article to another through accident, ignorance or carelessness. Admixture may occur through faulty collection, as collecting the drug not at the proper time e.g. collecting solanaceous leaves in summer; Colchicum corm in early summer. 4- Deterioration; this means impaired of the quality of the drug by destruction of a valuable constituents by distillation, extraction, aging, moisture, heat, fungi as, whole Clove partially exhausted by distillation, Coffee which lost its caffeine through over-roasting. 5- Spoilage; a special form of deterioration in which the quality of an article is impaired or destroyed by the action of fungi and this article unfit for human consumption. 6- Inferiority; is adding any sub-standard (containing less amount of A.C.) substances for any cause as synthetic substances to drugs. 8  Medicinal Plants CELL CONTENTS The cell contents are those which can be identified by microscopical examination or by chemical and physical tests. 9  Medicinal Plants Reserve food materials 1- CARBOHYDRATES Carbohydrates are organic compounds composed of carbon, hydrogen and oxygen, where the later two are present of the ratio 2:1 like that of their presence in water. Starch: ▪ Starch is a polysaccharides of high molecular weight, with the general formula (C6H6O5)n and is one of the most widely distributed cell contents in plants ▪ It is formed as a result of the photosynthesis process which is carried out by the green parts of the plant. 6CO2 + 6H2O → C6H12O6 + 6O2 ▪ The formed glucose molecules are condensed together to give starch nC6H12O6 → (C6H10O5)n + nH2O Kinds of starch 1- Assimilatory: it is found as small granules in the chloroplasts of the green parts. It is temporary, being hydrolyzed during darkness. 2- Transitory: It is deposited in the medullary rays, xylem, phloem and pith in the form of small granules which are used up by the growing organs. 3- Reserve: It is present in storage organs as large size granules. This kind constitutes all starches used for economic and medicinal purposes. Chemical composition of starch granules Starch consists of two components which differ in physical properties. 10  Medicinal Plants 1- Amylose The inner layers of the granules More water soluble and less viscous in solution.It is responsible for the blue colour with iodine. Consist of 200-300 glucose (1, 4 linkage), and can be hydrolyzed by β- amylase into maltose. 2- Amylopectin The outer layers of the granules Less water soluble and more viscous. Gives bluish red or violet colour with iodine solution. Consists of 1000 glucose unites, most of which are connected with 1, 4 linkage. In addition to 1,6 linkage. Only 60% hydrolyzed by β- amylase into maltose. And the rest residue named dextrin which is 1,6 linkage. Properties of starch: 1- It is practically insoluble in cold water, but on boiling with water, it forms a white colloidal solution which forms jelly on cooling. 11  Medicinal Plants 2- On heating when dry at 150 °C – 160 °C it is converted to dextrin which is soluble in water. 3- It is stained blue with iodine, this colour disappear on heating and reappear on cooling. 4- It does not reduce Fehling’s solution, but on heating with dilute acids it is hydrolyzed giving glucose, which reduce Fehling’s solution. 5- Acid hydrolysis of starch gives glucose. 6-The enzyme β- amylase degrades starch to give maltose Maltose consists of two glucose units with α-1,4 linkage. Microscopical characters Shape: oval, polyhedral or round Hilum: It is the first part laid down in leucoplast, and around which the body of granule is deposited ✓ It is appears as a point or radiating ✓ It is in the centre (centric), or apart from centre (eccentric) Aggregation: 1- Simple: when the granule showing single hilum 2- Compound: when the granule is produced by deposition of layers around two or more hilum. 3- Semicompound: produced by deposition of layers forming a common layer of starch. Striation: Different layers of starch in the same granule forming alternate rings Concenteric, around the hilum , transverse, not around, distincit, faint, invisible, abscent. 12  Medicinal Plants 1- Potato starch Starch consists of the polysaccharide granules obtained from the tubers of Solanum tubersum, Family: Solanaceae 2- Maize starch Starch consists of the polysaccharide granules obtained from the endosperm of Zea mays, Family: Graminae 13  Medicinal Plants 3- Wheat starch Starch consists of the Polysaccharide granules obtained from the endosperm of Triticum vulgare, Family: Graminae 4- Rice starch Starch consists of the Polysaccharide granules obtained from the endosperm of Orayaza sativa, Family: Graminae Uses of starch 1. Starch suspension is used as antidote for iodine poisoning. 2. Used externally to prevent itching. 14  Medicinal Plants 3. Used as disintegrant in tablet, when the tablet reaches stomach, the starch absorbs water and the medication release. 4. Used in paper and cloth manufacturing. 5. Nutrient 6. In cosmetic 7. Used as emollient and as a base for suppositories. 8. Starting material for many products asLiquid glucose, dextrose, maltose, dextrin, soluble starch, insoluble starch, butanol, acetone and ethanol GUMS & MUCILAGE They are polysaccharide complexes formed from sugar and uronic acid units, these complexes are combined with metals. Gums are considered to be pathological products mucilage is formed by normal metabolism. Gums: are abnormal products, formed by - Injury of the plant - Unfavourable conditions (e.g. drought) - By a breakdown of cell walls (A process of extracellular formation called gummosis). Uses of gums 1. Suspending, emulsifying agents and adhesive. 2. Demulcent in cosmetics, emollient. 3. In tooth pastes and hand lotions. 4. As a masking agent for acrid tasting substances. 15  Medicinal Plants Mucilage Mucilages are generally normal products of metabolism formed within the cell (intracellular formation). Function of Mucilage - Storage material - Water storage reservoir - Protection for germinating seeds. Mucilage is often found in - Epidermal leaf cells (Senna) - Seed coats (linseed, psyllium) - Roots (marshmallow) - Barks Characters: 1. Solution of Ruthenium red (R.R) stains the mucilage of Senna and Buchu leaves with red color. 2. Solution of Corallin-soda stains the mucilage of Squill with red color. 3. They are stained blue with Methylene blue. 2- Protein Proteins are nitrogenous organic substances, give on hydrolysis polypeptides, dipeptides then amino acids. Storage protein occurs in the form of amorphous masses or small particles called aleurone grains, seen in the oily seeds. 16  Medicinal Plants The aleurone grain consists of a mass of protein surrounded by a thin membrane, the ground mass of protein encloses one or more rounded bodies or globoid and an angular body known as crystalloid. Characters 1. Proteins are stained red on warming with Million’s reagent. 2. Proteins are stained yellow with alc. solution of picric acid. 3. They are precipitated from solution by change pH or by high salt concentration as saturated soln. of ammonium sulphate. Examination of aleurone grains: The defatted section of the seed is placed in a drop of alc. solution of picric acid and left for a few minutes then washed with alcohol. A drop of alc. solution of eosin is added then washed well with alcohol and examined where the crystalloids take the yellow stain, the ground protein stained red and the globoids remain colorless. 3- Fixed oil and fats They are mixture of ester of fatty acids with glycerol. They are greasy, non-volatile and at room temperature, liquid as Olive oil, semi-solid as lard or solid as fats of Cacao butter. Fixed oils and fats are widely distributed and often occur in seeds as a reserve food material. 17  Medicinal Plants Fats occur in solid or feathery crystals as in endosperm of Nutmeg or prisms as in Lobelia. Fixed oils occur as drops associated with aleurone grains in cotyledons of Linseed, Castor seed. Fixed oils and fats are mixture of ester of fatty acids with glycerol. CH2OCOR CH2OH H2O CHOCOR 3 RCOOH + CHOH Fatty acids CH2OH CH2OCOR Fatts and fixed oils Glycerol Characters They are greasy, non-volatile Insoluble in water, soluble in ether and chloroform Leave permanent stain on paper. Hydrolyzed by alkali giving soap (sod salt of fatty acid) and glycerine saponification. Hydrolysis of fats by boiling with alkali is a saponification process. Waxes: They are esters of fatty acids but in this case combined with higher monohydric alcohols such as ceryl or palmetic alcohol. Waxes hydrolyzed with KOH giving higher alcohols. 18  Medicinal Plants Uses Some oils are used in treatment of skin diseases. Some oils are laxatives. Some oils are used as emollient. Some oil as cod liver oil used in rickets and T.B Some waxes are used as bases for ointments. Some fats promote absorption of drugs through skin. Non-living cell contents: end products (non- active constituents) CRYSTALS Calcium Oxalate Ca oxalate is a very common cell content in the plant kingdom. It is formed in the cell as end product of metabolism being a result of the reaction of calcium salt and oxalic acid produced during metabolism of carbohydrates. Crystals exhibit variation in size and shape. 19  Medicinal Plants Forms of crystals They occur in drugs with different forms. The form in particular drug is constant and so afford valuable diagnostic value for this drug These different forms classified into; A- Solitary or single (of common occurrence). 1- Scattered prisms e.g. hyoscyamus 2- Twinned crystals e.g. hyoscyamus 3- - Styloid e.g. in quillaia. (columnar elongatted prism). 4- Acicular or needle shape crystals: needle-shaped crystals very narrow and pointed at the two ends found scattered in the cell sap and not in bundles e.g. cinnamon But Bundle of acicular crystals embedded in mucilage e.g squill. Named Raphides. 20  Medicinal Plants B- Aggregated crystals 1- Raphides of acicular crystals 2- Cluster crystals: aggregated crystals (prisms) radiating irregularly from a central point. e.g. Datura strammonium. 3- Rosette crystals: formed of aggregated crystals (prisms) radiating from one central point but in one plane. e.g. Umbelliferae 4- Microcrystals or crystal-sand: (Idioblastes): These are very minute crystals occurring together in large number being either: Micro-prismatic as in Cinchona. Microsphenoidal as in Belladonna. 5- Sphero-crystals or Spherities: rare occurrence, formed of needle- shaped crystals radiating from common centre as in fungi 21  Medicinal Plants The arrangements of crystals of calcium oxalates in the plant tissues is sometimes of diagnostic value, crystal layer in Datura and crystal sheath in Senna Also, absence of calcium oxalates in plant tissue give a valuable aid in identification of drugs as Boldo, Digitalis, Rosmary, Mentha, Lavander and Saffron Calcium carbonate Calcium carbonates are embedded in the cell wall and called cystoliths (e.g. cannabis). It can be identified by its solubility with acetic acid with effervescence. 22  Medicinal Plants How could you differentiate between calcium oxalates and other crystalline substances? 1. Ca.ox. soluble in HCL without effervescent. (c.f. calcium carbonate). 2. Ca.ox. decomposes with 20% H2SO4 and forms needles of calcium sulphates. 3. Ca.ox. Do not react with barium chloride solution (c.f. calcium sulphate). 4. Very slowly affected by solution of caustic alkalis the crystals disappear within few weeks (other calcium salts dissolve rapidly). 23  Medicinal Plants Active constituents These are chemical compounds synthesized by the living cells and possesses physiological activity. 1-VOLATILE OILS General properties They are known as ethereal or essential oils. They are volatile with steam and don’t leave any permanent oily stain on the filter paper. All volatile oils have characteristic aromatic odour. They can be prepared by steam distillation. The families rich in V.O are Labiatae, Rutaceae, Umbelliferae , Lauraceae and Compositae. They are secreted in: oil cells ex. Cinnamon, secretion ducts ex. Fennel , glandular hairs ex. Mentha, Chammomile, and glands ex. Buchu V.O are not saponified by alkalies. Roles of V.O in plants 1. Eliminate certain abnormal metabolic products and thus may be detoxification products. 2. Attract the insects, thus aid in pollination of the flower. 3. Act as repellents to insects (defense agent). 4. Serve as solvent for wound healing resins. Frequently they associated with substance as resins (Oleoresin) or gums (Oleo gum resin). 24  Medicinal Plants Chemical tests 1. Suddan III reagent-------- red colour 2. Alkanna Tr.--------- red colour. 3. Osmic acid -------- brown colour. 4. On spotting on filter paper -------- no permanent stain Composition of Volatile Oils  Volatile oils are generally mixtures of hydrocarbons and oxygenated compounds derived from these hydrocarbons.  The unit of them is isoprene unit.  Almost any type of organic compound may be found in volatile oils (hydrocarbons, alcohols, ketones, aldehydes, ethers, oxides, esters, and others). “usually volatile oils are classified according to the type of organic compounds”. H2 C C CH CH2 CH3 CH2 CH3 C CH CH CH C CH CH Head CH3 Tail 2 2 2 Myrcene 25  Medicinal Plants Difference between Volatile and Fixed Oils Items Volatile oil Fixed oil Nature mixtures of mixture of ester of fatty hydrocarbons and acids with glycerol oxygenated compounds derived from these hydrocarbons Condition Volatile Non volatile Separation Steam distillation expression Occurrence Secretory Endosperm and embryo structures Stain on paper Give No stain Give stain Saponification Not saponified saponified Alcohol soluble Sparingly soluble 2- RESIN AND RESIN COMBINATIONS Resins are solid or semisolid organic compounds of complex chemical nature but free from nitrogen. Resins on heating soften and finally melts. They are water insoluble but soluble in alcohols, fixed and volatile oils. They are heavier than water. Resins are prepared from pants by incision or by extraction with alcohol, then precipitation with water. Resins are often associated with: ◊- volatile oil oleo- resin ◊- gums gum - resins. ◊- oil + gum oleo – gum – resins. ◊- sugars glucoresin 26  Medicinal Plants May form balsams which are resins containing benzoic or cinnamic acids or their esters as balsam Peru. 3- BALSAMS Balsams are resinous mixtures that contain balsamic acids (benzoic acid or cinnamic acid) or esters of these acids.Balsams have aromatic odour Example: balsam tolu, balsam peru 4- BITTER PRINCIPALS Bitter Principals are compounds composed of carbon, hydrogen and oxygen and free from nitrogen. They have bitter taste. Found in families: Compositae, Labiatae. 5- TANNINS ❑ They are soluble in alcohol, acetone & alkali. ❑ They are soluble in water forming colloidal solutions having astringent taste. They are precipitated from aqueous solutions by lead acetate. ❑ They are used as antidote in alkaloid or heavy metal poisoning, they form precipitates with many alkaloids. ❑ Used as reagent for detection of proteins, gelatin and alkaloids (precipitation). ❑ Used in tanning process Tannins combine with protein in animal hides, prevent putrefaction and convert them into leather. ❑ Used in treatment of burns and GIT disorders because they are astringent. 27  Medicinal Plants When tannins are applied to the non-living tissue the process is known as tanning process. When tannins are applied to the living tissue the process is know as astringent. Used in treatment of burns. Tanninscombine with protein and form insoluble compound, the skin becomes less permeable to water and less susceptible to putrefaction and swelling. Classification and structure: Tannins can be classified into 2 main groups according to phenolic compounds enter in constitution of tannins. 28  Medicinal Plants 6- ALKALOIDS Alkaloids are basic nitrogenous compounds found in plants and possess marked physiological activity but some of them are highly toxic. Most alkaloids are crystalline substances and contain the elements C, H, O and N in their molecules ; but few are liquids and oxygen free as nicotine and coniine. Nomenclature: Names should end by "ine". These names may refer to: 1. The genus of the plant, such as Atropine from Atropa belladona. 2. The plant species, such as Belladonnine from Atropa belladona. 3. The common name of the drug, such as Ergotamine from ergot. 4. The name of the discoverer, such as Pelletierine that was discovered by Pelletier. 5. The physiological action, such as Emetine that acts as emetic. 6. A prominent physical character, such as Hygrine that is hygroscopic Classifications True (Typical) alkaloids that are derived from amino acids and have nitrogen in a heterocyclic ring. e.g Atropine Protoalkaloids (Atypical) that are derived from amino acids and do not have nitrogen in a heterocyclic ring, but in side chain. e.g Ephedrine Pseudo alkaloids that are not derived from amino acids but have nitrogen in a heterocyclic ring. e.g Caffeine False alkaloids are non alkaloids give false positive reaction with alkaloidal reagents. 29  Medicinal Plants Basic nucleus of alkaloids Function: 1. They may act as protective against insects due to their bitterness and toxicity. 2. Source of nitrogen in case of nitrogen deficiency. 3. They, sometimes, act as growth regulators in certain metabolic systems. 4. They may be utilized as a source of energy in case of deficiency in carbon dioxide assimilation. General characters: Physical Alkaloids are usually colourless, odourless, crystalline, non- volatile and bitter in taste. Only few are coloured e.g. berberine and colchicine are yellow in colour. Few are liquids and odourous ( oxygen free) as nicotine and coniine. 30  Medicinal Plants Some alkaloids contain phenolic group or carboxylic group, they are amphoteric forming salt with acids and alkali. ex morphine Alkaloidal reagents A- Alkaloidal precipitating reagents They react with alkaloids giving precipitates (addition compounds). The following are examples of alkaloidal precipitating reagents: 1) Mayer's reagent (potassium mercuric iodide): It gives creamy precipitate. It gives white precipitates with all alkaloids except purine bases, ricinine and colchicine. 2) Wagner’s reagent (iodine potassium iodide). 3) Dragendorff’s reagent (potassium bismuth iodide): It gives orange- red ppt. It is also widely used for chromatographic identification of alkaloids. Both reagents produce crystalline precipitates with definite shapes, enabling identification and differentiation of certain chemically related alkaloids, e.g. hyoscyamine, hyoscine and atropine B- Colour producing reagents. General colour reagents 1) Erdman's: sulphuric acid containing a trace of nitric acid. 2) Froehd's: sulphomolybdic acid or ammonium molybdate. 3) Marqui's: sulphuric acid containing formaldehyde. 4) Mandelin's: sulphuric acid containing vanadic acid or ammonium vanadate. 31  Medicinal Plants Examples of some important alkaloids of common uses 7- GLYCOSIDES Glycosides are non-reducing substances, consist of a sugar part bound to a different structure called the aglycone or genin. The physiological action of glycosides is due to aglycone. The role of sugar is stabilization and solubilization. The sugar is necessary to carry the aglycone to site of action where the pharmacological action is intended. Classifications according to the Glycosidic Linkages between sugar and aglycone The sugar moiety can be joined to the aglycone in various ways: 1. Oxygen (O-glycoside) 2. Sulphur (S-glycoside) 3. Nitrogen (N-glycoside) 4. Carbon (Cglycoside) 32  Medicinal Plants O-Glycosides can easily be cleaved into sugar and aglycone by hydrolysis with acids or enzymes. Almost all plants that contain glycosides also contain enzymes that bring about their hydrolysis (glycosidases). Glycosides are usually soluble in water, whereas aglycones are normally insoluble or only slightly soluble in water. Hydrolysis of glycosides Glycosides do not reduce Fehling solution except after hydrolysis. 1- Acid hydrolysis The linkage between sugar and aglycone is hydrolysis in acid medium. The linkage is more split than the linkage between the individual sugars of the saccharide part of the glycoside. Note: C-glycoside is strongly resistant to normal acid hydrolysis. In aloin, the sugar is joined to aglycone with a direct C-C linkage 2- Alkali hydrolysis ✓ Certain glycosides are modified or brocken down to the aglycone or sugar part by alkali. The lactone ring in cardiac glycosides is opened by strong alkali and loss activity. 3- Enzyme hydrolysis The glycoside is easily hydrolyzed by an enzyme which occurs in the same plant, in different cells. Example. Myrosin & emulsin Types of glycosides Classifications according to the Glycosidic Linkages between sugar and aglycone Classifications according to pharmacological action (Cardiac glycosides, Renal disinfectants, Anti-inflammatory glycosides. Laxative glycosides) 33  Medicinal Plants Classification based on chemical nature of aglycone: 1- Phenolic glycosides: A-Simple Phenolic glycosides B- Anthracene glycoside C- Flavonoid glycoside D- Coumarin glycoside 2- Saponins 3- Cyanophore glycosides 4- Thioglycosides 5- Cardiac glycosides Phenolic glycosides A-Simple Phenolic glycosides They have aglycone containing phenolic groups together with either alcoholic group or carboxylic acid group. e.g arbutin and salicin Test: with ferric chloride gives blue colour. They have antiseptic activity, diuretic activity (caution need to replenish potassium) Arbutin, is effective in the topical treatment of hyperpigmentations. Melanin production was inhibited significantly by arbutin. 34  Medicinal Plants B-Anthracene glycosides The aglycones are anthracenes derivatives and having laxative action. These anthracene glycosides are sometimes referred to as the anthraquinone glycosides or the anthraglycosides. The anthracene derivatives occur in vegetable drugs in different forms at different oxidation levels; like anthraquinones, anthrones, anthranols, oxanthrones or dimeric form (dianthrone). Test for free anthraquinone Add KOH to the powder extract, rose-pink colour is formed Test for combined anthraquinone Borntrager's test 1- Boil powdered drug with 10% H2SO4 for 2 minutes to hydrolyze the glycoside 35  Medicinal Plants 2- Filter while hot, cool, extract with benzene 3- To the benzene layer add half of its volume ammonia, shake well and allow separating, the amonnical layer will take a rose-pink colour Note: this test will be negative if there is very stable anthraquinone glycoside or reduced form of anthranol type Microsublimation test gives needles or droplets of anthrquinones, which gives a red colour with alkali. C-Flavonoid glycosides These are the largest group of phenolic glycosides. They present both in free state and as glycosides. This group is described as a series of C6-C3- C6. The flavones are yellow (Flavus = yellow). The intensity of yellow colour increase with number of hydroxyl groups. Uses of flavonoids 1. Diuretic. 2. Antispasmodic. 3. Diaphoretic. 4. Increase strength of capillary walls, decrease capillary fragility.. 5. Decrease bleeding tendency in scurvy (deficiency of vit C. 6. Antioxidant 36  Medicinal Plants 7. These compounds have high importance in nature as colour attractants to insects and birds as an aid to plant pollination. Chemical tests 1. With aluminum chloride give yellow colour. 2. With KOH give yellow colour. 3. Alcoholic solution of flavonoids when treated with magnesium metal and HCl give an orange, red or violet colour (shinoda test) Examples Diosmin It is diuretic and urinary tract antiseptic. Diosmin is used for various disorders of blood vessels including hemorrhoids, poor circulation in the legs ,and bleeding (hemorrhage) in the eye or gums. Silymarin Occur in fruits of Silybum Used as antihepatotoxic D-Coumarin glycosides They are derivatives of benzo-pyrone, Some coumarins are phytoalexins and are synthesized by the plant following infection by a bacterium or fungus. Phytoalexins: any of a group of compounds formed in plants in response to fungal infection, physical damage, chemical injury, or a pathogenic process. Phytoalexins inhibit or destroy the invading agent. Examples of coumarins Scopoletin Antimicrobial, it is synthesized by the potato (Solanum tuberosum) following fungal infection. 37  Medicinal Plants Khellin Natural product from Ammi Visnaga and has activity in Kidney stones (khellin relaxes smooth muscle of ureters and ease the passage of renal calculi), Asthma ( vasodilator and relieve attacks of angina pectoris) Psoralen and Bergapten. Natural product from Ammi majus, these compounds may be produced by the plant as a protection mechanism against high doses of sunlight. They are formulated into sunscreens and cosmetics for this purpose. It is used externally for treatment of (Vitiligo) (leukoderma), stimulates pigment production in skin exposed to UV light. Chemical tests There is no specific test for coumarin , but each compound is tested separately. A rose red colour is produced when the powder of Ammi visnaga is treated with solid KOH. The alcoholic extract of A. majus gives a blue fluorescence in Ultraviolet light. Saponins They are group of glycosides(Latin Sapo, means Soap). The aglycones of the saponins are referred to as Sapogenins. General characters: 1. They foam in aqueous solution, persistent foam. 2. They cause haemolysis of red blood cells. 3. have sternutatory odour, and cause irritation to mucous membrane of eyes and nose. 4. Have emulsifying properties so can be used as detergents. 38  Medicinal Plants Structure of Saponins: According to the structure of the aglycone or sapogenin, two kinds of saponin are recognized: 1. The steroidal type (commonly tetracyclic C-27). 2. The pentacyclic type, ( C-30). Both of these have a glycosidal linkage at C-3. Steroidal saponins are of great pharmaceutical importance because of their relationship to compounds such as the sex hormones, cortisone, and vitamin D. Uses 1. Expectorant 2. Steroidal saponins are used as precursors for synthesis of testesterone and cortisone. 3. Treatment of addison disease. 4. Used to increase viscosity and secretion of gastric mucosa. Example : Ginseng 1. Activate the synthesis of proteins. 2. Stimulate the synthesis of bone marrow. 3. Normalize the blood pressure and blood sugar level. 4. Protect liver cells. 5. Increase physical and mental performance. 6. Antifatigue 39  Medicinal Plants Cyanophore glycoside They named also Cyanogenetic glycoside (Cyanide glycosides).These compounds, in presence of enzymes such as -glucosidase, lose their sugar portion to form a cyanohydrin which, in the presence of water, can undergo hydrolysis to give benzaldehyde and the highly toxic hydrogen cyanide (HCN). Cyanophore glycosides do not have wide range of applications, because of poisonous properties of hydrocyanic acid, which is evolved through enzymatic hydrolysis.They can be used as sedatives and in cough syrups Chemical test Guignard reaction Freshly crushed linseed boiled in w.b with water for 30 min at 37 C, at top of tube put paper wetted with sodium picrate (yellow) _____HCN will formed and the paper turned red (sod picramate) Examples: Amygdalin in bitter almonds and Linamarin in linseed 40  Medicinal Plants Thioglycosides They named also thiocyanate or sulfurated glycosides. They contain sulfur. Chemical Test: on paper chromatography, spray with silver nitrate, dry, respray with potassium dichromate, the glycosides appear as yellow spots against a red back ground of silver dichromate Sinigrin In presence of water, the enzyme myrosin will hydrolyse it producing glucose, potassium acid sulphat and Allylisothiocyanate which is Pungent taste, pungent odour volatile liquid. No odour, when soaked with water strong pungent odour evolved. War gas is Allylisothiocyanate. It causes irritation of the eye, lacrimation, irritation of respiratory system, increase secretion of mucous membrane, asphyxia and finally death. Cardioactive glycosides (Cardiac) Cardiac glycosides are a group of natural products characterized by their specific effect on myocardial contraction. In large doses they are toxic and bring about cardiac arrest, but in lower doses they are important drugs in the treatment of congestive heart failure. They have a diuretic activity. Since, 41  Medicinal Plants the improved circulation tends to improve renal secretion, which relieves the edema often associated with heart failure. On the basis of the lactone ring structure, the aglucone in cardiac glycosides are devided into two main groups: 1- Cardenolide have unsaturated 5-membered lactone ringattached to C17. ex. Digitalis & Strophanthus. 2- Bufadienolide have unsaturated 6-membered lactone ring attached to C17. ex. Squill. The existence of the unsaturated lactone rings play the largest role in the cardioactivity. The attachment with the receptor and hence the action of cardiac glycosides is achieved through a hydrogen bonding between the receptor and the lactone ring. If the lactone ring is saturated , the activity is reduced to 1|10 to 1|20 of the original, while opening of the ring will abolishes the activity. (remember alkaline hydrolysis. 42  Medicinal Plants Example Squill, bufadienolides White variety: contains Proscillaridin A, scillaren A, it is Cardiotonic (proscillaridin A), and diuretic properties. it is an expectorant, but it also possesses emetic. Red variety : contains scilliroside and glucoscilliroside; proscillaridin A and scillaren A as in the white variety.I t is used as a rat poison (scilliroside), because rodents lack the vomiting reflex, which makes red squill particularly lethal to these animals. Digitalis glycosides, Cardenolide Digitalis purpurea (Red foxglove leaves), Purpurea glycosides A and B 1ry glycoside ) ,digitoxin and gitoxin (2ry glycoside) Digitalis lanata (White foxglove leaves), Lanatosides A, B, C and D Keller-Kiliani test: Extract the powder with chloroform. Evaporate to dryness. Dissolve the residue in glacial acetic acid containing traces of FeCl3. Transfer to test 43  Medicinal Plants tube, add conc. H2SO4 on the wall. An intense blue colour develop at the surface between the two layers. 8- Enzymes They are high molecular weight proteins, they are organic biocatalyst produced by living cells, The action may be 1- specific : ex. Invertase enzyme which hydrolyses sucrose into glucose and fructose. 2- general : ex. Emulsin which hydrolyses most glycosides. Enzymes are inactivated by heat. 9- Vitamins They are organic substances necessary to the normal growth and maintenance of life. Some are oil soluble A,D,E,K Some are water soluble C, B-complex 44  Medicinal Plants POWDERS OF NATURAL OCCURRENCE Lycopodium Consists of ripe spores of the common clubmoss Lycopodium clavatum F.:Lycopodiaceae. Physical characters: Color: Pale yellow. Odor: Odorless. Taste: Tasteless. Dilute acids and alkalis: No reaction. Flame: Blown into a flame it burns with brilliant flash. Microscopical examination: Each spore is tetrahedral. Three faces are flat and triangular while the fourth is rounded –triangular and convex. The convex surface is entirely covered with a fine network of 4-6 sides and produce a honey combed appearance. Active Constituents: 1- 40-50% fixed oil (glycerides of lycopodium-oleic acid 80% and myristic acid 2%). 2- 3% sugars and phytosterin and sterols. 3- Traces of alkaloids mainly (lycopodine). Uses: 1- Dusting powder in pills manufacturing. 2- In quantitative microscopy. 3- Manufacturing of firework due to fixed oil. 45  Medicinal Plants Lupulin It Consists of the glands obtained from the strobiles of Humulus lupulus F.: Cannabinaceae. Physical characters: Color:Brownish yellow. Darken in color during storage. Odor:Hop like odor. Taste:Bitter aromatic. Microscopical characters: Each gland consists of a cup-shaped layer of cells, the cuticle of the concave surface of which has been raised, dome-like, by the secretion of oil or oleo-resin between it and the cell wall. Active Constituents: 1- Volatile oil (terpenes and sesquiterpenes) 2- bitter principle (phloroglucinol derivtives as humulone and lupulone) 3- resin and wax 4- Choline base Uses: 1- stomachic tonic 2- hypnotic to promote sleep 3- preparation of beer During storage lupulin acquires an unpleasent odour of valerianic acid due to decomposition of the oil and one of the resin. 46  Medicinal Plants Kamala It is the glands and hairs that covers the fruits of Mallotus philippinensis F.: Euphorbiaceae. Physical characters: Color: Dull red, it floats on water surface. Odor: Odorless. Taste: Tasteless. Microscopical characters: Glands:Depressed globular and filled with a deep red resin, secreted by several club-shaped cells radiating from a common center. Hairs:Thick–walled curved, unicellular and arranged in small radiating groups. The walls are lignified. Active Constituents: 1- 11% phloroglucin anthlemintic derivatives as rottlerin and iso- rottlerin 2- 60% resin 3- 2% wax Uses: 1- effective remedy for tapeworm, expelling the worm and producing free purgation 2- Taenicide 3- In veterinary medicine for treatment of poultry 4- for dying of silk 47  Medicinal Plants Diatomite Consists almost of Siliceous Skeletons of fossil diatoms F: Bacillariceae. Physical characters: Color:Light brownish grey and after acid treatment, white powder. Touch:Smooth. Odor:Odorless. Taste: Tasteless. Solubility:Insoluble in water or any organic solvent. Density:Low due to large air volume enclosed by it. Microscopical examination: Diatoms skeleton is formed of 2 parts, each of which consists of a flat or slightly wave siliceous plate which varies much in shape & may be oblong,oval, circular, triangular, sigmoid or of some complex shape, it is named the valve.The 2 portions fit together like the lid and box. Diatoms vary in size from about 5 to 100 up to 500 µ. Active constituents 75-92% silica with traces of aluminum oxide 1-6% calcium oxide 0.2-1.5% magnesium and iron oxide Uses Clarification, filtration and decolorization Manufacture of toothpaste, face powder, soaps and nail polishers In chromatography as support for column and thin layer chromatography 48  Medicinal Plants Chalk Native calcium carbonate purified by elutriation. There are 2 groups: Precipitated chalk:By interaction of a soluble salt and a solublecarbonate. CaCl2 + Na2CO3 Ca2CO3+ 2 NaCl Prepared chalk:Consists mainly of the shells of unicellular animals known as the foraminifera. Physical characters: Color:White. Touch:Soft. Taste:Tasteless. Odor:Odorless. Solubility:Insoluble in H2O but absorb it. Effervesces with acids (for differentiate between Chalk and Talc). Microscopical examination: Precipitated chalk:Appears as minute crystalline particles. Prepared chalk: Shells of unicellular animals (foraminifera). Active constituents; 98% calcium carbonate 0.5% magnesium carbonate 1% silica Traces of aluminum, iron and magnesium oxides and of sulphates, phosphates and organic matter 49  Medicinal Plants Uses Dusting powder Preparation of tooth and face powder Antacid Treatment of diarrhea. Talc (FRENCH CHALK) Purified native hydrated magnesium silicate. H2O.3 MgO.4 SiO2 Physical characters: Color: White. Taste: Tasteless. Odor: Odorless. Touch: Fine and has greasy feel when rubbed on the skin (slip on skin). Solubility: Insoluble in H2O, acids and alkalis. Density: High (2.2 – 2.8). Microscopical examination: Minute particles of various size and shapes, the particles are irregular,sharply angular & often show jagged & laminated ends. Active constituents Hydrated magnesium silicate having the formula Mg6(Si2O5)4(OH)4 2% iron oxide and traces of aluminum oxide The greyish tint of some varities being due to iron oxide present Uses Clarification and filtration of cloudy fluids Preparation of dusting powder Lubricant for massaging and in the making of tablets 50  Medicinal Plants Plant anatomy The cell wall; the original cell wall may, differentiation of the cell, are the deposition of further cellulose or hemicellulose and incrustation of the wall by lignin, cutin, or suberin. So cell wall has the following types; 1- Cellulose walls; certain colour reaction can be applied for the recognition of cellulose cell walls. The colour reactions vary with differences in the relative proportions of cellulose, hemicellulose and pectin present; a- Chlor-zinc-iodine → a blue with true cellulose, yellow colour → pectin substances. b- Iodine → no colour with true cellulose, blue colour → hemicellulose. 2- Lignified walls; lignin is a strengthening material which impergnates the cell walls of tracheids, vessels, fibers, and sclereids of vascular plants. For identification of lignified walls; Phloroglucinol + conc. HCl → walls stained red colour. 3- Suberized and cutinized walls; Suberin and cutin consist of mixtures of highly polymerized fatty acids, these materials waterproof cells in which they occur. Suberin thickening are found in cork cell and endodermal cell. The reaction of suberin and cutin are almost identical; a- Chlor-zinc-iodine ……yellow to brown colour. b- Sudan III-glycerin …… red colour especially on worming. 4- Mucilaginous cell wall; gum and mucilage are polysaccharides complex formed from sugar and uronic acid units. Certain cell walls may be converted into gums and mucilages, a- Ruthenium Red (R.R) ……. red stain 51  Medicinal Plants 5- Chitinous walls; chitin , forms the major part of the cell walls of insects and many fungi. It gives no reaction for cellulose or lignin, but when heated with 50% potash at 160-170°C for 1 hour gives chitosan a- Chitosan + excess of alkali gives precipitate. b- Chitosan + 0.5% solution of iodine in potassium iodide + 1% H2SO4 gives blue color. Types of cells Parenchymatous cells; Characterized by isodiametric form, large in size and with large intercellular spaces, in plant functionally in photosynthesis, secretion and storage. Can be differentiated into chloronchyma which is parenchumatous cells contain chloroplasts or palisade cells or into lignified parenchyma. Collenchymatous cells; Collenchyma is a living tissue, directly derived from parenchyma, but having greater mechanical strength. The walls are thickened, the thickening being composed of cellulose, small in size, with small intercellular spaces. The cells are usually four to six-sided in transverse section. Sclerenchyma or sclereids; Sclereids or stone cells, the walls of typical sclereid are thick, lignified, often showing well-marked stratification. The cell lumen is usually small, cell contents of diagnostic significance may present as prisms of calcium oxalate, starch grains. Sclereids commonly occur in the hard outer coats of seeds 52  Medicinal Plants Xylem The primary xylem is composed of protoxylem and metaxylem. The structural elements of xylem are tracheids, vessels, xylem fibers, and xylem parenchyma. The xylem parenchyma cells are often axially elongated, sometimes thin walled, but often walls showing thickening and lignification and act as storage tissue. 53  Medicinal Plants Vessel Elements Water conducting tubes. Formed from a number of cells placed end to end, by partial or complete disintegration of end walls. In T.S. the vessels appear circular or polygonal, having wide cell cavity. The vessels have no cytoplasm. They are not living. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. protoxylem show annular or spiral type, where the vessels of metaxylem show scalariform and reticulate type. Tracheids Water conducting element and serve for support. It is a single elongated cell without sharp ends. The end wall separating tracheid from one another is not perforated. Unlike vessel elements, do not have perforation plates. 54  Medicinal Plants Fiber Each fiber is single , nonliving, very much elongated cell, and having usually tapering ends. It has very thick, lignified pitted walls and narrow lumen. In T.S. it is polygonal. 1- Septate fiber: it has at interval, delicate partitions of cellulosic nature. 2- Substitue fiber: it is living, contains starch, has lignified wall. Phloem The structural elements of the phloem include. Sieve tubes, Companion cells, Phloem parenchyma, Phloem fibers, and transversed by medullary rays. The phloem medullary rays are formed of radially elongated parenchyma cells. Medullary rays may be one cell wide(uniseriate), to many cells(multiseriate) 55  Medicinal Plants Sieve tubes Are the fundamental element of the phloem and may constitute the greater part of the phloem. They are long tubes formed of elongated polygonal cells. The tubes are formed of many cells arranged end to end and connected together by sieve plates.The sieve tube is the conducing element of the phloem; Companion Cells The companion cell is an elongated, narrow, thin walled cells showing a prominent nucleus.It lies along the sieve tube segment and is connected by pits with it. Types of vascular bundles A-Collateral: It consists of a patch of phloem and another of xylem lying in the same radius. If cambium in between → Open (dicotyledons). If no cambium in between → Closed (mocotyledons). B-Bicollateral: Where the xylem is between two patches of phloem, all lying on the same radius, the external phloem is separated from the xylem 56  Medicinal Plants by cambium and the inner is separated from the protoxylem by ordinary parenchyma. C- Amphicribial: It is usually with no cambium and having the xylem in the center surrounded by phloem. D-Amphivasal: It is usually with no cambium and having the phloem in the center surrounded by xylem. E-Radial: It is usually consists of alternating masses of xylem and phloem 57  Medicinal Plants Secretory tissues Tissues that contain and produce secretion e.g. volatile oils, resin, mucilage, gum….etc They are either internal including 1. Secretory cells, The cells are named according to secretions, e.g; oil cells contain oil. Other secretions may be resin, mucilage or tannin. 2. Secretory cavities or sacs (glands), This is a special structure, having cavity Whith in which secretions e.g. V.O or resin. They are classified according to method of formation: I- Schizogenous Develpoed by separation of the cells, thus enclosing a cavity, which then becomes enlarged. II- lysigenous Developed by lyses of the cells, forming a cavity III- Schizolysigenous The cavity is developed at first schizogenously, later on increase in size by breaking down of the inner cells 58  Medicinal Plants 3. Secretory ducts or canals These are tube-like structures. They usually produce volatile oil or oleo-resin. The secretory ducts are either developed schizogenously,, lysigenously or schizolysigenously. 4. laticiferous structures These include cells and vessels, the secretion of these elements is called latex, which is a colourless, milky white, yellowish, or red, highly viscous colloidal emulsion contain of variable composition as Alkaloidal salts, tannin, sugars in aqueous solution. Laticiferous structures are almost commonly in the phloem. A- Laticiferous cells; B- laticiferous vessels; are long, simple, or branched tubes formed of longitudinal series of cells, the transverse walls of which may be either partially or completely dissolved 59  Medicinal Plants THE LEAF Definition: ❑ The leaf is a lateral outgrowth on the stem, but differing in structure and function since it does not possess nodes or internodes and lateral branches arise in its axil. ❑ At first all cells are meristematic and after leaves formation, the meristematic cell loses its activity and divides no more. The further growth of the leaf is due to the increase in the size of the cells and to maturation of mesophyll and vascular tissue but not to formation of new cells. Types of the Leaves: 1. The Cotyledons (seed-leaves): They are the leaves of the embryonic plant in the seed. They serve for storage of food or as absorptive organs. 2. The Prophylls: The first leaves are borne on a branch and are simpler in structure than ordinary leaves. 60  Medicinal Plants 3. The Foliage leaves: These are the ordinary green leaves, which carry out normal leaf functions and are green in color due to the presence of chlorophyll. It is the type of pharmacognostic interest because it is the type of all the commercial leaves used in medicine. 4. The Bracts: They are leaves having a flower or a group of flowers in their axils and are smaller than ordinary leaves. A whorl of bracts surrounding a group of flowers is called involucre, as in families of Compositae (Asteraceae), and Umbelliferae. 5. The Scale leaves: They occur on all subterranean stems and on some aerial stems and are thin, membranous, and devoid of chlorophyll. 6. The Floral leaves: Those include sepals, petals, stamens, and carpels. They have no buds in their axils. 7. The Modified leaves: The whole leaf or part of the leaf is modified into special structure for carrying out a special function, e.g. tendrils for climbing, spines for protection, traps for catching insects for nutrition, etc. Phyllotaxis: It is the disposition of the leaves on the stem. The different types of phyllotaxis are: ❑ Alternate or spiral: When the leaves are inserted singly at the nodes (the most frequent type). ❑ Opposite: When a pair of leaves is developed at each node and leaf is 61  Medicinal Plants opposite to the other. ❑ Opposite decussate: The leaves are opposite, and each pair is inserted at right angles to the pairs immediately above and below. ❑ Whorled or verticillate: When three or more leaves occur at each node and arise in a circle around the stem. Structure of the Leaf The complete leaf is composed of three parts. Leaf base Petiole or leaf-stalk Lamina or leaf-blade 1-Leaf-base: ❑ It is the part of the leaf by which it is attached to the stem and is slightly enlarged. It sometimes extends round the stem, forming a large sheath enclosing the stem or part of it, this case being more common in monocotyledons. ❑ In some cases, the leaf-base develops lateral outgrowths called stipules. ❑ Both the leaf-base and the stipules serve for protection of the young axillary buds. ❑ When the stipules are present, the leaf is described as stipulate, when absent, it is described as exstipulate. 62  Medicinal Plants ❑ When the lower part of the sessile lamina continues as wings down the stem, the leaf-base is described as decurrent. 2-Petiole (or Leaf Stalk): ❑ It develops between the lamina and the leaf-base. When it is absent, the leaf is described as sessile, while when present, it is petiolate. ❑ Sometimes, the petiole shows a localized swelling called pulvinus as in Leguminosae. The length of the petiole varies from one leaf to another even on the same plant. It is often longest in the lower leaves but gradually becomes shorter near the top of the plant. 3-Lamina (or Leaf-Blade): ❑ When the lamina consists of a continuous, undivided surface, the leaf is described as simple. ❑ When it is cut up into a number of lobes connected together, it is said to be lobed or divided. In some cases, the lamina may be completely segmented into a number of separate leaflets and is called compound. ❑ The lobed leaf is a simple leaf with an incised margin. If the incision is directed towards the midrib, the leaf is pinnately-lobed, but if it is directed towards the top of the petiole, the leaf is said to be palmately-lobed. Compound Leaves: ❑ The compound leaf consists of 2 or more leaflets which may be arranged on a central axis called rachis, corresponding to the midrib of the leaf. 63  Medicinal Plants Types of Compound Leaves: ❑ Binate: With 2 leaflets. ❑ Ternate: With 3 leaflets, two lateral and one terminal. ❑ Palmate: With 5 or more leaflets radiating from the top of the petiole. ❑ Pinnate: With several leaflets arranged on the rachis. It may be paripinnate, with leaflets in two rows, one on either side of the rachis, or imparipinnate, with leaflets in two rows, but terminating with a single leaflet. Description of Lamina: 1. Shape: ❑ Filiform: thread-like (e.g. Fennel). ❑ Acicular: needle-shaped (e.g. Pinus). ❑ Tubular: (e.g. Onion). ❑ Linear: Flat and narrow (e.g. Grass). ❑ Oblong: flat, wide with parallel edges near the middle. ❑ Lanceolate: narrow, but wider below the middle (e.g. Long Buchu). ❑ Ovate: with an outline like that of an egg (e.g. Boldo). ❑ Ensiform: sword-shaped (e.g. Eucalyptus). ❑ Cordate: heart-shaped. ❑ Reniform: kidney-shaped. ❑ Obovate: inverted egg-shaped (e.g. Dog Senna). ❑ Spathulate: like a spoon (e.g. Uva-ursi). 64  Medicinal Plants 2. Size: Length is measured from base to apex and width is measured at the broadest part. In leaves used in medicine, the size does not exceed 30 cm long. 3. Apex: ❑ Acute: The two sides of the margin form an acute angle at the tip, e.g. Hyoscyamus. ❑ Acuminate: The point is longer than in acute and the apex is more tapering, e.g. Stramonium. ❑ Obtuse: Blunt or rounded. ❑ Recurved: Curved backwards, e.g. Short Buchu. ❑ Mucronate: Acute, terminating in a sharp point (apiculus), e.g. Senna. ❑ Emarginate: With an acute apical notch, e.g. Jaborandi. 4. Margin: ❑ Entire: even and smooth. ❑ Revolute: rolled back, e.g. Uva-ursi. ❑ Crenate: with numerous rounded lobes. ❑ Dentate: having teeth pointing straight outwards. 65  Medicinal Plants ❑ Serrate: having sharp teeth directed towards the apex. ❑ Ciliate: having hairs. 5. Base: ❑ Symmetric: Equal on both sides of the midrib. ❑ Asymmetric: Unequal on both sides of the midrib. ❑ Decurrent: as in Belladonna. ❑ Cordate. ❑ Reniform. 6. Venation: This may be: ❑ Parallel: several veins of almost equal size run side by side, parallel to each other, e.g. monocots. ❑ Reticulate: the lateral veins branch off into smaller veins and veinlets forming a network appearance. When lateral veins extend from one main vein, called midrib, to the margin at frequent intervals and in a regular manner, venation is described as pinnately-reticulate. When there is no midrib, but instead there are several divergent main veins running from base to apex, venation is described as palmately-reticulate. 66  Medicinal Plants 7. Surface: The upper surface is usually dark green, while the lower is paler. The midrib is usually prominent on the lower surface. The surface is described as: ❑ Smooth. ❑ Punctate: when dotted with projections from oil glands, e.g. Buchu. ❑ Rugose: wrinkled. ❑ Glabrous: completely free from hairs. ❑ Pubescent: hairy, covered with short hairs, e.g. Hyoscyamus. ❑ 8. Texture: 1. Membraneous: very thin and pliable. 2. Papery: thin like paper. 3. Coriaceous: thick and leathery, e.g. Boldo. 4. Succulent: thick and fleshy, e.g. Aloes. Structure of Lamina: The ordinary leaf consists of epiderms and mesophyll. 1. The Epidermis: ❑ It usually consists of a single layer of cells with no intercellular spaces, except where the pores of stomata occur, but may become many-layered and in this case acts as H2O storage tissue. ❑ Epidermal cells are tabular or lenticular and appear polygonal in surface view, being isodiametric in dicots and axially elongated in monocots. The anticlinal walls are either straight or wavy and may be beaded due to unequal thickening in the angles, e.g. Digitalis. ❑ The outer walls are covered by an impermeable layer, the cuticle (formed mainly of cutin), which may be smooth or finely ridged, appearing striated in surface view. In rare cases, epidermal cells may show contents, e.g. calcium oxalate, diosmin in Buchu, mucilage. 67  Medicinal Plants Hairs (Epidermal Trichomes) Papillae:- short projection of epidermal cells to outside. Hairs (trichomes):- long projection of epidermal cells to outside. Function of Hair 1. Physical and chemical protection for the leaf against microbial organisms and insects. 2. Its secretion used in perfumes, food and pharmaceutical industry. Classification A) Non-glandular hairs (clothing or covering hairs) 1- Unicellular hairs a) Branched --------- Cruciferae b) Unbranched------- Senna 2- Multicellular hairs a) Branched 1- Simple (uniseriate body ending into two branches------Tobaacco 68  Medicinal Plants 2- Stellate (radiating unicellular hairs ------ Boldo 3- Peltate (very short stalk surrounded by plate like structure ------- Cascarilla 4- Candelabra hairs -------- Lavender & Rosmary b) Unbranched 1- Uniseriate ----- belladonna 69  Medicinal Plants 2- Biseriate-------- Arnica & Calendula 3- Pluri-seriate (shaggy hair) ------ Cumin B) Glandular hairs 1- Uniseriate stalk (one celled stalk) a) Unicellular head ------ Digitalis or Mentha b) Multicellular head ------ two (Digitalis) or more (Datura) 70  Medicinal Plants 2- Biseriate stalk and biseriate head (compositae hair) 3- Pluri-seriate-------- Cannabis 4- Branched stalk -------- Hyoscyamus muticus Stomata The stomata consist of two similar cells parallel to each called guard cells enclosing a small oval shaped space called osteole. Osteole Guard cell 71  Medicinal Plants Types of stomata The epidermal cells surrounding the stomata called subsidary cells according to characters and arrangement of these cells the stomata were classified to: 1. Anisocytic or cruciferous stomata (unequal celled): surrounded by 3 subsidiary cells one of them is smaller than the others. (e.g. solanaceae and compositae) 2. Anomocytic or ranunculaceous stomata (irregular celled): The surrounding cells are varying in numbers, have no special arrangement, and do not differ from other epidermal cells. (e.g. Digitalis and Buchu) 72  Medicinal Plants 3-Paracytic or rubiceous stomata (parallel celled): surrounded by 2 subsidiary cells their long axes parallel to the osteole. (e.g. Rubiaceae and Senna) 4. Diacytic or caryophyllaceous stomta (cross celled): surrounded by 2 subsidiary cells their long axes perpendicular to the osteole. (e.g. Labiatae) 73  Medicinal Plants 5. Actinocytic stomata (star-celled): surrounded by a circle of cells. (e.g Uva ursi) Mesophyll - It is divided into two layers Palisade layer spongy layer Palisade layer Formed of one or more layers of cylendrical cells having the long axis perpendicular to the epidermis. - They show narrow intercellualr spaces. It is usually interupted by the cortical tissue in the midrib region, but in some cases the upper palisade may form a continous layer Spongy layer - Composed of loosely arranged cholrenchyma cells of irregular shape, this layer contains fewer chloroplasts and has many intercellular spaces for the diffusion of gases (required for respiration and photosynthesis), linked to the outside by means of stomata. According to the arrangement of the mesophyll, the leaf is described Isobilateral leaf Dorsiventaral leaf 74  Medicinal Plants Isobilateral leaf - The mesophyll is symmetric on both sides showing one or more layers of palisade cells on both the upper and lower epidermis. Dorsiventaral leaf - The mesophyll is not symmetric showing only one palisade layer below the upper epidermis while the rest of mesophyll is formed of irregular parenchyma. Palisade Ratio: The average number of palisade cells beneath each cell of the upper epidermis (It is constant for each leaf STRUCTURE OF THE MIDRIB Epidermis Cortical tissue - It is present mainly in the midrib region and big veins. It may be formed of parenchyma (Belladona) or collenchyma (Uva Ursi) or both. Endodermis - It is the inner most layer of the cortical tissue, is usually indistinguishable. When recognisable it often takes the form of starch sheath as in digitalis leaf. The pericycle It lies between the phloem and the cortical tissue; it is mostly parenchymatous, sometimes collenchymatous or may consist of lignified fibers below the vascular bundles. Vascular system: Consists of xylem vessels (towards the upper epidermis), cambium and phloem (towards the lower epidermis) 75  Medicinal Plants Xylem: radial rows of vessels with protoxylem towards the upper epidermis and separated by wood parenchyma. Medullary rays may be visible, traversing the xylem and phloem. Cambium: always not distinguishable, being either absent or represented by little cambiform tissue between xylem and phloem Phloem: thin-walled elements Stramonium Leaf Datura leaf, Thorn apple Origin: It is the dried leaves, with or without the flowering tops of Datura stramonium, Family Solanaceae. Macroscopical characters: Petiole: petiolated Lamina: ovate or triangular ovate cordate base dentately lobed serrate margin 76  Medicinal Plants acuminate apex brittle texture Upper surface --- green Lower surface ---- paler Both surfaces are nearly glabrous. Odor--- characteristic taste---bitter Upprer collenchyma Upper epiderms parenchyma pericycle endodermis xylem Palisade layer cambium phloem Perimedullary phloem Crystal of Ca. ox. Lower collenchyma Lower epiderms T.S. Diagram 77  Medicinal Plants Histological characters The leaf is dorsiventral 1. Epidermis polygonal cell with anisocytic stomata and hairs occur as Non-glandular hair (uniseriate 3-5 celled some of them is collapesd) Glandular hairs (solanaceous hair, uniserriate 1 celled stalk and multicellular head) 2. Cortex a- Hypodermis---collenchyma b- Parenchyma cells containing crystal of Ca. oxalate 3. Endodermis (Starch sheath) 4. Pericycle (p. parenchyma and p. fibers) 5. Collateral vascular bundle a- Xylem b- Phloem c- Groups of perimedullary phloem 78  Medicinal Plants Powder and isolated elements Non-glandular hair Crystal layer Epidermal cell with anisocytic stomata Non-glandular collapsed hair Numerous cluster Solanaceous hair crystals of CaoX Active constituents It contains 0.26 to 0.75% of total tropane alkaloids mainly : hyoscyamine, hyoscine (scopolamine) and Atropine. Uses It is used mainly due to the effect of the tropane alkaloids specially atropine, as following: 1. CNS stimulant (atropine), respiratory stimulant and in large doses leading to restlessness and hallucination. 79  Medicinal Plants 2. used in ophthalmic practice as mydriatic to dilate the pupil of the eye. Atropine is contraindicated in glaucoma (raised intraocular pressure (IOP). 3. Antispasmodic effect in case of intestinal and renal colic. It is smooth muscle relaxant (GIT, bladder, ureter). Hyoscine derivatives are more potent, and most widely used as antispasmodic. 4. Smooth muscle relaxant (bronchodilator) relief asthma & relax airway. Decrease body secretion (sweet, urine,, gastric, salivary, bronchial) 5. Decreasing the salivary secretions so used as pre-operative drug as pre-anesthetic agent. Hyoscine is better 6. Decreasing gastric secretions so used in treatment of peptic and duodenal ulcer. 7. The antidote of choice for overdose or poisoning with Physostigmine. 8. Treatment of uncontrolled urination, relax bladder. 9. Treatment of common cold as nasal decongestant, release of epinephrine. Hyoscine: 1- Sedative. , lack CNS stimulant action 2-Antiemetic in motion sickness 3- Antispasmodic. 4- pre-anethetic agent General test for alkaloids Shake powder of Stramonium with dil. HCl, filtrate and add to the filtrate a drop of Mayer’s reagent. A white or yellowish white ppt. is formed. 80  Medicinal Plants Specific test for tropane alkaloids Vitali’s Test Evaporate the alkaloids, cool, add few drops of fuming nitric acid, evaporate on water bath. The residue is cooled and then moistened with few drops of freshly prepared alcoholic solution of KOH (10%). A violet colour develops which slowly fades away. Hyoscyamus muticus leaf (Egyptian Henbane) Oigin: it is the dried leaves and flowering tops of Hyoscyamus muticus linne. Family Solanaceae G. S. : Egypt, Saudi Arabia Persia and Western Punjab. Macroscopical characters: Petiole petiolated. Lamina oval Tapering to symmetric base Margin entire or with 2 to 5 teeth on each side Acuminate apex. Color --- pale green to yellowish Odor--- slight narcotic Taste---bitter acrid Midrib broad prominent on the lower surface. 81  Medicinal Plants Microscopical characters: Leaf is isobilateral Lamina 1- Epidermis (upper and lower ) Striated thick cuticle- anisocytic stomata Non-glandular hair (few and short – uniseriate and multicellular). Glandular hair (numerous- Branched and non branched stalk with globular unicellular head) 2- Mesophyll Isobilateral Single layer of palisade on both side. Prisms of Ca. oxalate (Twins) Midrib 1- Epidermis (upper and lower) as lamina 2- Cortex a- No collenchyma b- Parenchyma cells containing prisms crystal of Ca. oxalate (twins) 3- Endodermis (Starch sheath) 4- Pericycle (p. parenchyma and p. fibers) 5- Collateral vascular bundle a- Xylem b- Phloem c- Groups of perimedullary phloem 82  Medicinal Plants Parenchyma Upper epiderms Endodermis Pericycle Upper palisade Xylem Phloem Lower Palisade layer Crystal of Ca. ox. Perimedullary phloem Lower epiderms T.S. Diagram 83  Medicinal Plants Powder and isolated elements Active constituents and uses As Datura leaf 84  Medicinal Plants HYOSCYMUS NIGER LEAF (FOLIUM HYOSCYMI, EUROPEAN HENBANE LEAVES) Origin: dried leaves with or without flowering tops of Hyoscymus niger Family: solanaceae Morphological characters Petiole: upper leaves are sessile and small and lower are long with broad petiole Shape: ovate to triangular ovate Apex: acute Margin: dentate to sinuate Surface: hairy Vennation: pinnate retculate Colour: dark green to greyish green Odour: slight Active constituents Hyoscyamine and trace of hyoscine Uses 1-Spinal sedative, used in insomnia when opium can not be given. 2- Relieve gripping caused by purgatives 85  Medicinal Plants 86  Medicinal Plants BELLADONNA LEAF (HERBA BELLADONNA, DEADLY NIGHT SHADE LEAVES) Origin: dried leaves with or without flowering tops of Atropa belladonna Family: Solanaceae Morphological characters Petiole: short petiole Shape: oval lanceolate to broadly ovate Apex: acute to acuminate Base: slightly deccurrent Margin: entire Surface: thin and papery glaborous Vennation: pinnate retculate Colour: light green to brownish green Odour: slight Taste: bitter and acrid 87  Medicinal Plants Numerous green fragments of mesophyl with idioblasts of microsphenoidal crystals of uniseriate, multicellular, usually 2-6 cells with thin, solanaceous hair, uniserriate 1 celled stalk and multicellular head 88  Medicinal Plants Active constituents Alkaloids: Hyoscyamine, hyoscine and atropine Uses As Datura leaves SENNA LEAF Synonyms: Sanamakki. Origin Dried leaflets of Cassia acutifolia (Alexandrian or Khartoum Senna) and of Cassia angustifolia (Tinnevelly or Indian Senna) (Fam. Leguminosae). Morphological Description: o In both varieties of Senna, the leaves are compound paripinnate, petiolate and leaflets are arranged on both sides of the rachis. Alexandrian Senna: o The leaflets are shortly petiolate, the lamina is lanceolate to ovate lanceolate and is pale greyish-green in color. o The apex is acute mucronate with a distinct apiculus and the base is asymmetric. o The margin is entire and slightly revolute. Both surfaces of the leaflet are very slightly hairy. 89  Medicinal Plants ❑ Venation is pinnate reticulate, veins are distinct on the lower surface, leaving the midrib at acute angles. ❑ Indian Senna: ❑ The leaflets are less hairy and may show some depressed lines on the surface. ❑ Senna has a faint characteristic odor with a mucilaginous and bitter taste. Histological Description: ❑ The leaflets of both varieties show an isobilateral structure. pper palisade ricyclic er epidermis prisms lo er palisade ylem collenchyma holem The Epidermis: ❑ It consists of a single row of polygonal tabular cells, with straight anticlinal walls and stomata of the paracytic type on both surfaces. ❑ The cells contain mucilage which stains red with Ruthenium Red reagent. ❑ Hairs are present; they are non-glandular, unicellular, thick-walled, with a warty cuticle and curved near the base. ❑ When a hair falls off, the scar of its base, the cicatrix, can be seen in a surface section. 90  Medicinal Plants The Mesophyll: ❑ It shows a single layer of palisade cells abutting on each epidermis, except in the midrib region, where only the upper palisade is continuous, ❑ Idioblasts containing cluster crystals of calcium oxalate are scattered in the spongy mesophyll. ❑ The midrib shows a crescent-shaped, collateral vascular bundle, accompanied by an arc of lignified pericyclic fibers below and a compact mass of lignified fibers above, parenchyma containing prismatic crystals of calcium oxalate abutting on these groups of fibers forming a crystal sheath. Microscopical Identification: ❑ Numerous green fragments showing epidermal cells with stomata of paracytic (rubiaceous) type and warty hairs or their thickened cutinised cicatrices, surrounded by radiating epidermal cells. ❑ Idioblasts of cluster crystals of calcium oxalate. ❑ Isolated non-glandular unicellular hairs with a warty cuticle, curved at the 91  Medicinal Plants base. ❑ Fragments of lignified vessels. ❑ Fragments of bundles of lignified fibers accompanied by crystal sheath. Active Constituents:. Glycosides: anthraquinone derivatives, sennoside A, B, C and D - Flavonoids Mucilage Uses Small dose is laxative while large dose is purgative Chemical Identification: Test for free anthraquinone Add KOH to the powder extract, rose-pink colour is formed Test for combined anthraquinone Borntrager's test 1- Boil powdered drug with 10% H2SO4 for 2 minutes to hydrolyze the glycoside 2- Filter while hot, cool, extract with benzene 3- To the benzene layer add half of its volume with ammonia, shake well and allow separating, the amonnical layer will take a rose-pink colour Substitutes and Adulterants: Dog Senna (Cassia obovata): ❑ The leaves are sometimes broken up and mixed with broken Alexandrian Senna; they may be recognised by the papillosed cells of the lower epidermis. Bombay Senna: ❑ The leaflets are usually more elongated and the color is darker. 92  Medicinal Plants Cassia auriculata: ❑ The thick-walled, unicellular trichomes are about three times as long as those of the two genuine Senna species and possess a fairly smooth cuticle. BUCHU LEAF Origin: It is the dried leaves of Barosma betulina (round buchu),Barosma crenulata (oval buchu) & Barosma serratifolia (long buchu) Family: Rutaceae Morphological Description: ❑ The leaf is simple, very shortly petiolate and the lamina is rhomboid, obovate and green to yellowish-green in color. ❑ The apex is blunt and strongly recurved, the margin is dentate, becoming serrate towards the base. ❑ The midrib is prominent on the lower surface and venation is pinnate, with only four lateral veins distinct. ❑ The surface is almost glabrous, punctate, not smooth due to small scattered prominences, caused by the presence of scattered oil glands in the mesophyll as well as the marginal glands, one of which is situated at the base of each indentation and one in the apex of the lamina. ❑ Buchu leaf has a strong, aromatic and characteristic odor, especially when crushed and a strong and aromatic taste. 93  Medicinal Plants Histological Description: The leaf shows a dorsiventral structure. The Epidermis: -It consists of polygonal cells with straight anticlinal walls, thick cuticle and containing a thick deposit of mucilage on the inner tangential walls and sphaerocrystalline masses or aggregates of feather-like crystals of diosmin, which is soluble in KOH solution, producing a yellow color. -Stomata are present on the lower surface only, each surrounded by 4 to 6 cells, of anomocytic type. -Non-glandular hairs are very few, present especially on the midrib, unicellular, conical, thick-walled. 2. The Mesophyll: -It shows a single layer of palisade cells, continuous in the midrib, spongy tissue containing cluster crystals of calcium oxalate and ovoid 94  Medicinal Plants schizolysigenous oil glands. The midrib shows a crescent-shaped vascular bundle, with radiating xylem and a narrow phloem, and an arc of pericycle of non-lignified fibers below. Microscopical Identification: Powdered Buchu is light green in color, with a strong aromatic odor and taste. Microscopically, it is characterized by: -Fragments of epidermal cells with sphaero-crystals or aggregates of feather-like crystals of diosmin. -Numerous green fragments with oil glands and numerous globules of volatile oil. Very few simple hairs. Cluster crystals of calcium oxalate. -Fragments of vascular tissue and non-lignified pericyclic fibers. Hyaline angular particles of mucilage, which stain pink with Ruthenium Red solution. 95  Medicinal Plants Active constituents - Flavonoid Diosmin - Volatile oil diosphenol - Mucilage Therapeutic Uses: - Diuretic - Urinary tract antiseptic - Increase strength of capillary walls, decrease capillary fragility. - Diosmin is used for various disorders of blood vessels including hemorrhoids, poor circulation in the legs ,and bleeding (hemorrhage) in the eye or gums. Chemical test Powder with KOH gives yellow colour (flavonoid) With Sudan III gives red colour (oil) With Rhuthenium red gives red colour (mucilage) DIGITALIS LEAF Synonyms: Folium Digitalis, Foxglove Leaves. Origin: Dried leaves of Digitalis purpurea (Fam. Scrophulariaceae) CULTIVATION AND COLLECTION: ❑ The plant is a biennial herb. It is propagated from seeds, it grows well in sandy soils. ❑ The best time of collection is June of the second year growth before expansion of the flowers. Collection should take place in dry conditions. 96  Medicinal Plants ❑ In the afternoon and drying is done as rapidly as possible at a fairly low temperature in the dark. Two methods are used for previously used for drying ❑ Hot air oven at about 55 to 60C°, the process takes from four of ten days. ❑ Using vacuum drying oven. The whole operation is completed in few hours. However, recently drying is done by freeze-drying (lypholization =drying in vacuum in a frozen state and ice sublimed from the frozen product at extremely low pressure). The dried leaves are packed in well filled, air tight, well-closed containers and protected from light, moisture which should nor exceed 5%. Morphological Description: ❑ The cauline leaf is oval-lanceolate to broadly ovate, with winged petiole, whereas the radical leaf is generally bigger and has longer petiole. ❑ The lamina of both leaves is decurrent at the base, with a sub-acute apex and an irregularly crenate but not serrate margin (distinction from D. lutea). ❑ The upper surface is dark green in color, wrinkled and hairy. ❑ The lower surface is greyish, almost whitish, due to the dense pubescence. ❑ Venation is pinnate reticulate, anastomosing near the margin and the basal veins continue into the wings of the petiole. Veinlets are depressed on the upper surface and are very prominent on the lower surface, forming a chequered appearance. ❑ Digitalis leaf has a slight or almost no odor when dry, becoming characteristic when moistened and a distinctly bitter taste. 97  Medicinal Plants Histological Description: The leaf shows a dorsiventral structure The Epidermis: ❑ It consists of cells with straight or slightly sinuous, not beaded (c.f. D. lanata) anticlinal walls, more strongly wavy in the lower epidermis and covered with thin smooth cuticle. Stomata are present on both surfaces, more numerous on the lower surface, each surrounded by 3-7, mostly 4 cells, of anomocytic (ranunculaceous) type. ❑ Glandular hairs are few, consisting of short unicellular, occasionally multicellular stalk and 1- or 2-celled head. ❑ Non-glandular hairs are numerous, uniseriate, multicellular, usually 3 to 5 celled and generally with thin walls, fine warty cuticle and blunt not acute tip; some of the cells may be collapsed. Each tooth of the margin exhibits 1, rarely 2 large H2O-pores on the upper surface. The Mesophyll: ❑ The mesophyll is sometimes undifferentiated. It consists of a palisade of a single layer of short cells and spongy mesophyll of several layers of stellate cells. ❑ The midrib shows an arc of vascular bundles with radiate xylem and narrow phloem, accompanied by collenchymatous pericycle of small cells and an endodermal starch sheath. Microscopical Identification: Powdered Digitalis is dark green in color, with a slight odor and a bitter taste. Microscopically, it is characterized by: -Numerous irregular fragments of epidermis with stomata of anomocytic (ranunculaceous) type. 98  Medicinal Plants -Numerous fragments of non-glandular, multicellular, uniseriate hairs showing collapsed cells and very few glandular hairs. -Fragments from the petiole and large veins showing spiral, annular, and reticulate vessels. -Sclerenchyma, fibers, and crystals of calcium oxalate are absent. Active Constituents: Digitalis purpurea and Digitalis lanata. 1. Digitalis purpurea (Red foxglove leaves) Purpurea glycosides A and B 1ry glycoside ) ,digitoxin and gitoxin (2ry glycoside) 2. Digitalis lanata (White foxglove leaves) Lanatosides A, B, C and D 99  Medicinal Plants Therapeutic Uses: 1.It is a cardiotonic. It increases the contractility and improves the tone of the cardiac muscle, both reactions resulting in a slower but much stronger heart beat. 2.It is used in most forms of cardiac failure. Chemical Identification: 1-Keller-Killiani test (for digitoxose): ❑ Boil 1 g of powdered Digitalis leaf with 10 mL of 70% alcohol for two to three minute