Active Constituents in Plants

Active Constituents

• Chemical substances synthesized by plants and found in crude drugs.
• Cannot be identified microscopically, but chemically identifiable using chemical tests.
• Classified based on their effect on plant life (primary and secondary metabolites) and chemical nature.

Classification

• Primary Metabolites: Essential for plant growth (carbohydrates, proteins, lipids, vitamins, hormones, enzymes).
• Secondary Metabolites: Cause plant protection (alkaloids, glycosides).

Volatile Oils

• Also known as essential oils or ethereal oils.
• Plant products producing characteristic odors and tastes.
• Secreted by plant structures like cells, glands, and ducts.
• Properties include oily liquids, volatile without decomposition (volatile in steam), ether-like volatility, soluble in organic solvents, sparingly soluble in water, presence as a mixture, not a single compound.
• Composition may be hydrocarbons or oxygenated hydrocarbons, free or combined with resins, gums, or sugars (forming glycosides).

Methods for Extraction of Volatile Oils

• Steam Distillation
• Organic Solvent Extraction
• Enzymatic Hydrolysis (in case of glycoside combination).

Plants Containing Volatile Oils

• Coriander (Fruit, Linalool)
• Clove (Flower, Eugenol)
• Eucalyptus (Leaves, Cineol)
• Peppermint (Herb, Menthol)
• Cinnamon (Bark, Cinnamic aldehyde)
• Cumin (Fruits, Cuminaldehyde)

Glycoside

• Natural products chemically bonded to sugar (glycone) and non-sugar part (aglycone).
• Non-reducing compounds.
• Can be linked by O-, S-, N-, or C-links.
• Non-sugar part can be terpenes, coumarins, anthraquinones, flavonoids, etc.
• Sugar part can be monosaccharides or deoxy sugars.
• Properties include colorless crystalline, soluble in water and diluted alcohol, insoluble in organic solvents.
• Functions include detoxifying agents, stabilizers for labile compounds, protection against microorganisms and insects, energy producers, and decorative substances.

Cardiac Glycosides

• Present in Digitalis purpurea and Digitalis lanata, Strophnthus.
• Used in treating heart diseases.
• The genin (non-sugar part) consists of a steroidal nucleus with four rings (three six-member rings and one five-member ring) attached to a lactone ring.
• The sugar part may consist of one to four molecules.
• Include tests like Killer Killiani's test, Liebermann's test, and Kedde's test.

Phenolic Glycosides

• Usually occur as glycosides and are soluble in water.
• Amphoteric, meaning properties can change depending on pH (affected by acids and alkalis producing color change).
• Examples include Salicin (a salicylate).

Flavonoid Glycosides

• Yellow colored polyphenolic compounds
• Soluble in water and alcohol
• Used as antiseptics, antioxidants, and anti-aging agents.
• Include tests involving alkali, ferric chloride, and aluminum chloride.

Anthraquinone Glycosides

• Contain an anthraquinone nucleus.
• Examples include Senna, rhubarb, aloe, and cascara.
• Used as laxatives, but not recommended in pregnancy due to irritation.
• Include Borntrager's test to detect free anthraquinone.

Thioglycosides (Sulfur Glycosides)

• Common in Cruciferae family.
• Hydrolyses produce glucose, potassium bisulfate and allylisothiocyanate (mustard volatile oil).
• Examples include black mustard (Sinigrin).

Cyanogenic Glycosides

• Hydrolyze to produce hydrogen cyanide (HCN).
• Examples include bitter almond (Amygdalin).

Saponin Glycosides

• Produce foam on shaking in aqueous solution.
• Hemolyse red blood cells.
• Lower surface tension.
• Examples include steroidal saponins (Digitalis) and triterpenoidal saponins (Licorice and quillaia).
• Applications include detergent, sex hormone preparation, and preparing cortisone.

Plant Pigments

• Classified as plastid pigments and other soluble pigments.
• Chlorophyll are complex Mg tetrapyrrole compounds, soluble in lipids/organic solvents, but insoluble in water.
• Carotenoids are tetraterpenes hydrocarbon compounds, soluble in lipids/organic solvents and appear as orange or red.
• Tests for fat-soluble pigments include tests of SbCl3/CHCl3, conc. HCl with phenol, and conc. H2SO4.
• Other soluble pigments include betacyanins, colored alkaloids, and some vitamins.

Alkaloids

• Basic nitrogenous compounds from plants.
• Do not form strong alkalis, but form salts when reacting with acids, usually have a complex, heterocyclic nitrogen structure.
• Properties includes solid, colorless, crystalline, and odorless to nonvolatile.
• Some are liquid (volatile or non-volatile), some are colored.
• Can be identified using reagents (e.g., Mayer's reagent, Wagner's reagent, Dragendorff's reagent).

Resins

• Solid or semisolid amorphous products of complex chemical processes.
• Soften when heated, melt and burn with smoky flames.
• Often contain resinotannols, positive for FeCl3 and are insoluble in water, readily soluble in alcohol.
• Includes colophony, ammoniacum, jalap, and guaiacum.

Tannins

• Water-soluble polyphenolic compounds.
• Have high molecular weight and widely distributed.
• Used to tan animal hides (precipitating proteins).
• Possess astringent taste.
• Classified as condensed (non-hydrolysable and catechol) or hydrolysable (gallic or ellagic and pyrogallol).
• Include testing for presence of tannins using acid, bromine, iron chloride and lead acetate.

Bitter Principles

• Aromatic heterocyclic compounds with bitter taste, absence of nitrogen.
• Diverse chemical structures.
• Examples include khellin from Ammi visnaga (furanochromone class) and xanthotoxin from Ammoidin (furanocaumarin class).
• Identification testing includes using potassium hydroxide (KOH).

تتناول هذه الكويز العناصر الفعالة في النباتات، بما في ذلك المكونات الكيميائية الأساسية والثانوية. سوف تستكشف دور هذه العناصر في نمو النباتات وحمايتها، بالإضافة إلى خصائص الزيوت الطيارة. هذا يساعد على فهم كيفية استخدام هذه المكونات في الأدوية والعلاجات.