Pharmacognosy Classification of natural products (2).pdf

Pharmacognosy Classification of natural products Classification of natural products Content: Pharmacognosist job can be refer to 3 HERBAL DRUGS DERIVED FROM SPECIFIC PARTS 4 ISOLATED COMPOUNDS FROM NATURE 6 NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ 10 Classification of Natural Products 20 Evaporation and...

Pharmacognosy Classification of natural products Classification of natural products Content: Pharmacognosist job can be refer to 3 HERBAL DRUGS DERIVED FROM SPECIFIC PARTS 4 ISOLATED COMPOUNDS FROM NATURE 6 NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ 10 Classification of Natural Products 20 Evaporation and Storage methods 47 Partitioning 49 Classification of natural products Pharmacognosist job can be refer to 1. Isolation & characterization of natural products 2. Study the pharmacology of natural drugs 3. Evaluation of quality. Quality control for products Pharmacognosist should have knowledge in a) Botany and medicinal plants b) Chemistry and Phytochemistry c) Pharmacology Classification of natural products HERBAL DRUGS DERIVED FROM SPECIFIC PARTS OF A MEDICINAL PLANT : Botanical drugs: Dried parts of entire plants, plant organs, or parts of plant organs, for use as medicines, aromatics, spices or additives. Form the basis for herbal remedies or phytomedicines include, for example: A. The herb of St John’s wort (Hypericum perforatum), used in the treatment of mild to moderate depression Classification of natural products B. The leaves of Ginkgo biloba, used for cognitive deficiencies (often in the elderly),including impairment of memory and affective symptoms such as anxiety C. The flower heads of chamomile (Chamomilla recutita), used for mild gastrointestinal complaints and as an anti-inflammatory agent D. The leaves and pods of senna (Cassia spp), used for constipation. ISOLATED COMPOUNDS FROM NATURE ISOLATED COMPOUNDS FROM NATURE : These are pure chemical entities, often used in the form of licensed medicines. They are sometimes produced synthetically and referred to as ‘nature identical’ (if that is the case) but were originally discovered from plant drugs. Examples include: A. Morphine, from opium poppy (Papaver somniferum), used as an analgesic ISOLATED COMPOUNDS FROM NATURE B. Digoxin and other digitalis glycosides, from foxglove (Digitalis spp.), used to treatheart failure C. Taxol, from the Pacific yew (Taxus brevifolia), used as an anticancer treatment ISOLATED COMPOUNDS FROM NATURE D. Quinine, from Cinchona bark (Cinchona spp.), used in the treatment of malaria E. Galanthamine from Galanthus and Leucojum species, used in the management of cognitive disorders. NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ : Many foods are known to have beneficial effects on health. Examples include:. A. garlic, ginger, turmeric and many other herbs and spices B. anthocyanin- or flavonoid-containing plants such as bilberries, cocoa and red wine C. carotenoid-containing plants such as tomatoes, carrots and many other vegetables. NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ Galenical pharmacy: branch of pharmacy which relates to the preparation of medicines by infusion, decoction, etc. It is named after Claudius Galen, a 2nd Century AD Greek physician, who codified the preparation of drugs using multiple ingredient What do we need to know about a medicinal plant? Botanical origin (species and family) Plant part which provides the drug NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ Type of product used: Ground plant material, Uncharacterized extract, Standardized extract, Isolated constituent Processed (special) extract Active constituents (if an extract, and if identified) Pharmacological effects and clinical effectiveness, side effects and interactions with other drugs. NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ Example of medical plant : 1. Botanical name : Curcuma domestica. (Zingiberaceae) Genus: Curcuma Species: domestica (domestic) Family: Zingiberaceae (the ginger family) Common names: turmeric NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ Part of plant: rhizome (underground stem) dried, and ground dark yellow powder Medicinal use: anti-inflammatory agent used in arthritis, psoriasis, for dyspepsia, ulcers and other gastrointestinal problems and for liver disease, Immunostimulant activity, and anticarcinogenic ,Antibacterial and antiprotozoal NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ Constituents: types of phytochemical present (Curcumin) Essential oil (about 3-5%), containing sesquiterpene ketones (‘turmerones’) including arturmerone, alpha-atlantone, zingiberene, plus borneol, eugenol and others - may contribute to activity Polysaccharides: glycans, ukonans A-D (‘starch’) NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ 2. Galantamine an alkaloid extracted from Galanthus nivalis belong to the Amaryllidaceae family Used for Alzheimer’s disease Mechanism of action: cholinesterase inhibitor ( raises levels of acetylcholine in brain areas lacking cholinergic neurons) Not curative, but slows down progression of illness NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ 3. The Opium poppy (Papaver somniferum) : Family name: Papaveraceae Medicinal use: analgesic (pain killer) Part of plant: opium, the dried latex from the unripe capsule (fruit) Constituents: alkaloids: morphine, codeine papaverine, thebaine and others Toxicity: depends - seeds and oil safe, alkaloids not! NUTRACEUTICALS OR ‘FUNCTIONAL FOODS’ Types of herbal extraction : 1. Infusions (teas) – ‘home made’ by patient 2. Decoctions – water extract as above, but boiled 3. Liquid/fluid extracts - made with ethanol and water – as above, often prepared by herbalist or commercially 4. Solid extracts – made by evaporating fluid extracts to dryness or semi-dryness; can be used to make tablets, tinctures, ointments etc Classification of Natural Products Classification of Natural Products Classification of Natural Products : The most important natural sources of drugs are (higher plants, microbes, animals and marine organisms. To follow the study of the individual drugs, one must adopt some particular sequence of arrangement and this is referred to a system of classification of drugs. A method of classification should be: Simple, Easy to use and Free from confusion & ambiguities. Classification of Natural Products Classification of Natural Products : Because of their wide distribution, each arrangement of classification has its own merits and demerits, but for the purpose of study the drugs are classified in the following different ways: 1. Alphabetical classification. 2. Morphological classification 3. Taxonomic classification 4. Pharmacological classification 5. Chemical classification 6. Chemo - taxonomical classification Classification of Natural Products Classification of Natural Products : 2. Morphological Classification In this system the drugs are arranged according to the morphological or external characters of the plant parts i.e. which plant part is used as a drug, e.g. leaves, roots, stems, etc. The drugs which obtained from the dried parts of the plants & containing cellular tissues are called as ( Organized Drugs ) e.g. Rhizomes , barks , leaves , fruits , entire plants , hairs ,& fibers. Classification of Natural Products The drugs which are prepared from plants by some intermediate physical processes such as ( incision , drying or extraction with a solvent and not containing any cellular plant tissues are called as ( unorganized drugs ) such as Aloe juice , opium latex , agar , gambir , gelatin , tragacanth , benzoin , honey , beeswax , lemon grass oil etc. Classification of Natural Products Morphology of Higher Plants 1. Flower It is the essential reproductive organ of a plant. For an inexperienced observer two characteristics of a flower are particularly noteworthy: the size and the color. Although the flowers are of great botanical importance, they are only a minor source of drugs used in phytotherapy or pharmacy e.g. chamomile (Matricaria recutita) L. (Asteraceae) Classification of Natural Products 2. Fruit :- Caraway (Carum carvi L.) (Umbelliferae) 3. Seed Coffee (Coffea arabica) (Rubiaceae) Classification of Natural Products 4. Leaves The leaves function as collectors of the sun ́s energy and its assimilation. A characteristic key of a species is the way how the leaves are arranged on the stem which they maybe: Alternate, Basal, Opposite, Decussate or Whorled. Classification of Natural Products Classification of Natural Products 5. Bark The bark as an outer protective layer frequently accumulates biologically active substances e.g. red cinchona (Cinchona succirubra L.) Classification of Natural Products Classification of Natural Products : 3. Taxonomical Classification Taxonomical classification is purely a botanical classification; it's based on principles of natural relationship & evolutionary developments. They are grouped in (Kingdom, Phyllum, Order, Family, Genus & Species). Classification of Natural Products 4. Pharmacological Classification In this system grouping of drug is according to a. Their pharmacological action. b. Their most important constituent. c. Their therapeutic use termed as pharmacological or therapeutic classification of drug. This classification is more relevant and mostly followed. Drugs like digitalis, squill and strophanthus having cardiotonic action are grouped together irrespective of their parts used or phylogenetic relationship or the nature of phytoconstituents they contain. Classification of Natural Products 5. Chemical classification The crude drugs are divided into different groups according to the chemical nature of their most important constituent. Since the pharmacological activity and therapeutic significance of crude drugs are based on the nature of their chemical constituents. The chemical classification of drugs is dependent upon the grouping of drugs with identical constituents. Classification of Natural Products Types of the chemical constituents: A. Primary metabolites : 1. Carbohydrates – Carbohydrates are polyhydroxy aldehydes or ketones containing an unbroken chain of carbon atoms. Gums - Acacia , Tragacanth Mucilages – Plantago seed. Others - Starch, Honey, Agar, Pectin, Cotton. 2. Protein – and amino acid e.g. Gelatin. Classification of Natural Products 2. Vitamins – riboflavin – 3. Lipids 4. Fixed oils Castor, Olive, Almond, Shark liver oil. Fats – Theobrama, Lanolin. Waxes – Beeswax. Classification of Natural Products B. Secondary metabolites 1. Glycosides: are compounds which upon hydr - olysis give rise to one or more sugar part (glycone) and non – sugar part (aglycone) Anthraquinone Glycosides – Aloe , Cascara , Rhubarb , Senna Saponins Glycosides –Q - uillaia , Glycyrrhiza. Cyanophore Glycosides – Wild cherry bark Isothiocyanate Glycosides – Mustard. Cardiac Glycosides – Digitalis, Strophantus. phenolic Glycosides – rutin , hesperidin Classification of Natural Products 2. Tannins: complex chemical substances derived from phenolic acids (sometimes called tannic acid). Ex: Pale catechu, Black catechu, Galls and Amla. 3. Volatile Oils – Monoterpines & Sesquiterpenes obtained from plants. Ex: Cinnamon , Fennel , Dill , Caraway , Coriander , Cardamom , Orange peel , Mint , Clove , Valerian. Classification of Natural Products 4. phenoilc compounds : Phenolic compounds can be defined as plant substances, which possess in common an aromatic ring bearing one or more hydroxyl groups. comprise flavonoids, phenolic acids, lignans, and coumarins, compounds Classification of Natural Products 5. Resins – Complex mixture of compounds like resinols , resin acids , resinotannols , resenes. Ex : Colophony , Podophyllum, Cannabis, Capsicum, Turmeric, Balsam of Tolu and Peru , Myrrh , Ginger. Classification of Natural Products 4. phenoilc compounds : Phenolic compounds can be defined as plant substances, which possess in common an aromatic ring bearing one or more hydroxyl groups. comprise flavonoids, phenolic acids, lignans, and coumarins, compounds 5. Resins – Complex mixture of compounds like resinols , resin acids , resinotannols , resenes. Ex : Colophony , Podophyllum, Cannabis, Capsicum, Turmeric, Balsam of Tolu and Peru , Myrrh , Ginger. Classification of Natural Products 6. Alkaloids – Nitrogenous substance of plant origin Pyridine and Piperidine – Lobelia, Nicotiana. Tropane – Coca , Belladonna , Datura, Stramonium , Hyoscyamus , Henbane. Quinoline - Cinchona Isoquinoline – Opium, Ipecac. Indol – Ergot , Rauwolfia. Amines – Ephedra Purine – Tea, Coffee. Classification of Natural Products Classification of Natural Products Classification of Natural Products Classification of Natural Products : 6. Chemotaxonomic Classification This system of classification relies on the chemical similarity of taxon i.e. It is based on the existence of relationship between constituents in various plants. There are certain types of chemical constituents that characterize certain classes of plants. Classification of Natural Products This gives birth to entirely new concept of chemotaxonomy that utilizes chemical facts / characters for understanding the taxonomical status, relationships and the evolution of the plants. The presence of such ubiquitous compounds as the essential amino acids and common sugars is of little diagnostic value and at the other extreme, the occurrence of coniine in the single species Conium maculatum of the large family Umbelliferae is also of little taxonomic significance. Classification of Natural Products Characters most studies in this connection are therefore secondary metabolites may of which are of established pharmaceutical interest. For example, tropane alkaloids generally occur among the members of Solanaceae thereby, serving as a chemotaxonomic marker. Similarly plant metabolites can serve as the basis of classification of crude drugs. Classification of Natural Products For example the berberine alkaloid in Berberis and Argemon, Rutin in Rutaceae members, ranunculaceous alkaloids among its members etc. It is latest system of classification and gives more scope for understanding the relationship between chemical constituents, their biosynthesis and their possible action. Evaporation and Storage methods Evaporation and Storage methods Evaporation and Storage methods : Regardless of the extraction technique used, extracts are concentrated under vaccum using rotary evaporators for large volumes of solvent. Removal of solvent should be carried out immediately after extraction, as natural products may be unstable in the solvent. Aqueous extracts are generally freeze‐dried using a lyophilizer. Evaporation and Storage methods Dried extracts should be stored at –20 C prior to screening for biological activity as this will decrease the possibility of bioactive natural product degradation Then the activity is demonstrated in a bioassay (e.g. an antibacterial test), the next step is to fractionate the extract using a separation method so that a purified biologically active component can be isolated. Partitioning Partitioning : Possibly the simplest separation method is partitioning, which is widely used as an initial extract purification and ‘clean up’ step. Partitioning uses two immiscible solvents to which the extract is added; this can be sequential by using immiscible organic solvents of increasing polarity. Partitioning Typically, this may take place in two steps: 1. water/light petroleum ether (hexane) to generate a non‐polar fraction in the organic layer. 2. water/dichloromethane or water/chloroform or water/ethyl acetate to give a medium‐polar fraction in the organic layer. The remaining aqueous layer will contain polar water‐soluble natural products. Partitioning This is a soft separation method and relies on the solubility of natural products and not a physical interaction with another medium (e.g. adsorption on silica gel in thin‐ layer chromatography, TLC). Partitioning may give rise to excellent separations, particularly with compounds that differ greatly in solubility; for example, monoterpenes are easily separated from phenolics such as tannins