GPAT Pharmacognosy Syllabus

Why is the time and season of collection critical for crude drugs?

Because the active constituent content varies with the plant's stage of growth and time of day/season; drugs must be collected when the active principle is at maximum concentration.

Name common techniques used in microscopy of crude drugs.

Light/optical microscopy, polarized microscopy, fluorescence microscopy, phase-contrast microscopy, electron microscopy (SEM/TEM), and use of staining/clearing reagents (e.g. phloroglucinol-HCl for lignin, iodine for starch).

Define phytoconstituents and name the two broad categories of plant metabolites.

Phytoconstituents are chemical compounds produced by plants. Categories: primary metabolites (carbohydrates, proteins, lipids, nucleic acids essential for growth) and secondary metabolites (alkaloids, glycosides, tannins, terpenoids, flavonoids).

Name the major biogenetic pathways producing secondary metabolites.

Shikimic acid pathway (aromatic amino acids, phenylpropanoids, lignans), Acetate-malonate (polyketide) pathway (fatty acids, phenols, anthraquinones), Acetate-mevalonate (MVA) pathway and MEP/DXP pathway (terpenoids, steroids), and the amino acid pathway (alkaloids).

Which biogenetic pathway gives rise to terpenoids and steroids, and what is the key C5 building block?

The mevalonic acid (MVA) pathway (and the alternative MEP/deoxyxylulose pathway). The key C5 isoprene unit is isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMAPP).

How are carbohydrates classified, with examples of pharmaceutically important ones.

Monosaccharides (glucose, fructose), oligosaccharides/disaccharides (sucrose, lactose), and polysaccharides (starch, cellulose, agar, acacia, tragacanth, pectin).

What is the iodine test used for, and what colour confirms starch?

Iodine test detects starch; starch gives a blue-black colour with iodine solution due to amylose-iodine complex (dextrin gives red, glycogen reddish-brown).

Classify lipids/fixed oils and state the test distinguishing fixed oils from volatile oils.

Lipids include fixed oils (triglycerides of fatty acids), fats, and waxes. Fixed oils leave a permanent translucent grease spot on paper (do not evaporate), whereas volatile oils evaporate leaving no permanent stain.

Define tannins and give the two main chemical classes.

Tannins are complex polyphenolic compounds that precipitate proteins (astringent). Classes: hydrolysable tannins (gallotannins, ellagitannins) and condensed tannins (proanthocyanidins, non-hydrolysable).

Name a chemical test for tannins.

Gold-beater's skin test, and reactions with ferric chloride (blue-black with hydrolysable / brownish-green with condensed tannins), gelatin solution (precipitate), and phenazone/bromine water tests.

Define volatile (essential) oils and how they differ from fixed oils.

Volatile oils are odorous, volatile, steam-distillable oily liquids of mixed terpenoid/aromatic constituents. Unlike fixed oils they evaporate without leaving a permanent grease spot and are not saponifiable.

What is the principal method of extraction of volatile oils, and name alternatives.

Steam (hydro) distillation is the principal method. Alternatives: enfleurage, expression (for citrus peels), solvent extraction, and supercritical CO2 extraction.

Chemically classify volatile oil constituents with examples.

Hydrocarbons (terpenes e.g. limonene, pinene), and oxygenated derivatives: alcohols (menthol, geraniol), aldehydes (cinnamaldehyde, citral), ketones (camphor, carvone), phenols (thymol, eugenol), oxides (cineole), esters (methyl salicylate).

Define resins and name the chemical sub-classes of resin combinations.

Resins are amorphous, solid/semi-solid complex mixtures of resin acids, resin alcohols (resinols), resenes and esters. Combinations: oleoresins, oleo-gum-resins, balsams, and glycoresins.

Differentiate a balsam from a resin, naming a chemical marker.

A balsam is a resinous mixture containing a high proportion of cinnamic acid, benzoic acid, or their esters (e.g. benzoin, Tolu, Peru balsam), whereas plain resins lack these aromatic balsamic acids.

Define a glycoside and name its two components.

A glycoside is a compound that on hydrolysis yields a sugar (glycone) and a non-sugar moiety (aglycone or genin); the two are joined by a glycosidic linkage.

How are glycosides classified based on the linkage atom?

By the glycosidic linkage atom: O-glycosides, C-glycosides, S-glycosides (thioglycosides), and N-glycosides; also classified pharmacologically/chemically (cardiac, anthraquinone, saponin, cyanogenetic, etc.).

Name the pharmacologically/chemically important classes of glycosides with one drug example each.

Cardiac (Digitalis), Anthraquinone (Senna, Aloe), Saponin (Liquorice, Dioscorea), Cyanogenetic (Wild cherry, bitter almond), Isothiocyanate/glucosinolate (Mustard), Flavonoid (Rutin), Coumarin (Psoralea), Bitter (Gentian).

What is the basic steroidal nucleus of cardiac glycosides and the lactone difference between cardenolides and bufadienolides?

The cyclopentanoperhydrophenanthrene (steroid) nucleus. Cardenolides have a 5-membered (alpha,beta-unsaturated butenolide) lactone ring; bufadienolides have a 6-membered (doubly unsaturated) lactone ring.

Define alkaloids and state their general characteristic properties.

Alkaloids are basic, nitrogen-containing (usually in a heterocyclic ring) plant secondary metabolites, mostly optically active, with marked physiological action; they give precipitates with alkaloidal reagents.

Name common alkaloidal precipitating (group) reagents.

Mayer's reagent (cream ppt), Dragendorff's reagent (orange-brown ppt), Wagner's reagent (reddish-brown ppt), Hager's reagent (yellow ppt), and tannic acid/picric acid.

Classify alkaloids based on the nitrogen-containing ring nucleus with examples.

Pyridine-piperidine (nicotine, lobeline), Tropane (atropine, cocaine), Quinoline (quinine), Isoquinoline (morphine), Indole (reserpine, ergometrine), Imidazole (pilocarpine), Steroidal (solanine), Purine (caffeine), and amino/pseudo/proto-alkaloids (ephedrine, colchicine).

Distinguish true, proto- and pseudo-alkaloids.

True alkaloids: N in a heterocyclic ring, derived from amino acids, basic (e.g. atropine). Protoalkaloids: amino-acid derived but N not in a ring (e.g. ephedrine, mescaline). Pseudoalkaloids: not amino-acid derived (e.g. caffeine, solanine).

Name common extraction techniques used for phytoconstituents.

Maceration, percolation, decoction, infusion, digestion, Soxhlet (continuous hot) extraction, reflux, ultrasound-assisted, microwave-assisted, supercritical fluid (CO2) extraction, and counter-current extraction.

Describe the principle of Soxhlet (continuous hot percolation) extraction.

The drug in a thimble is repeatedly extracted by fresh condensed solvent that siphons back into the flask; it gives efficient extraction with less solvent but is unsuitable for thermolabile constituents.

List chromatographic isolation techniques used for plant constituents.

TLC and HPTLC, column chromatography, paper chromatography, gas chromatography (GC), HPLC, flash chromatography, gel filtration, ion-exchange, and counter-current chromatography; hyphenated methods like GC-MS, LC-MS, LC-NMR.

What are phytopharmaceuticals as defined in Indian drug regulation?

A phytopharmaceutical drug is a purified and standardized fraction with defined minimum four bio-active/marker compounds (not less than 95%) derived from a medicinal plant, intended for internal/external human use, regulated as a distinct category under the Drugs & Cosmetics Rules.

What is standardization of herbal drugs and what are key WHO quality-control parameters?

Standardization confirms identity, purity and quality. Parameters include macro/microscopy, foreign matter, ash values, extractive values, moisture, heavy metals, microbial load, pesticide residue, aflatoxins, and marker-based quantitative assay (TLC/HPLC fingerprinting).

Define herbal formulations and name common dosage forms used in Ayurveda.

Herbal formulations are dosage forms made from standardized herbal extracts/powders. Ayurvedic forms include Churna (powder), Vati/Gutika (tablets/pills), Asava-Arishta (fermented), Kwatha (decoction), Avaleha (confection), Taila (oil), Ghrita (ghee), and Bhasma.

Differentiate Asava and Arishta.

Both are Ayurvedic fermented (self-generated alcohol) preparations. Asava is prepared using fresh juices or cold water decoctions, while Arishta is prepared using hot decoctions (kwatha) of the drugs; both ferment with a sugar source.

Name important natural pesticides/insecticides of plant origin and their source.

Pyrethrum (from Chrysanthemum cinerariaefolium flowers - pyrethrins), Nicotine (tobacco), Rotenone (Derris/Lonchocarpus roots), Neem (azadirachtin from Azadirachta indica), and Ryania.

Name pharmaceutically important enzymes of plant/animal origin with their use.

Papain (Carica papaya) and Bromelain (pineapple) - proteolytic/digestive; Diastase (malt) - amylolytic; Pepsin and Trypsin/Pancreatin (animal) - digestive; Serratiopeptidase - anti-inflammatory.

Give examples of pharmaceutical aids of natural origin and their function.

Acacia and Tragacanth (suspending/emulsifying agents), Agar and Pectin (gelling/suspending), Starch (disintegrant/diluent), Honey (sweetener/vehicle), Kaolin/Bentonite (adsorbents), and Gelatin (capsule shell, coating).

Name important toxic crude drugs and their toxic principles.

Nux vomica (strychnine), Aconite (aconitine), Belladonna/Datura (atropine, hyoscyamine), Castor seeds (ricin), Abrus (abrin), Ergot (ergot alkaloids), and Calotropis (calotropin).

Name important animal-origin pharmacognostic products and their uses.

Cod liver oil (vitamins A & D), Shark liver oil (squalene/vitamin A), Bees wax and Honey, Wool fat/Lanolin (ointment base), Musk and Civet (perfumery/fixatives), Gelatin, Heparin and Insulin (animal-derived), and Cantharides.

Name traditional herbal drugs (Indian) widely used, with their primary use.

Ashwagandha (adaptogen), Tulsi (immunomodulator), Brahmi (nootropic), Guggul (hypolipidemic), Shatavari (galactagogue/tonic), Amla (vitamin C/rasayana), Guduchi/Giloy (immunomodulator), and Turmeric (anti-inflammatory).

Define herbal cosmetics and give examples of herbs used in them.

Herbal cosmetics are cosmetic products containing phytochemicals/herbal ingredients that confer cosmetic plus therapeutic (cosmeceutical) benefits. Examples: Aloe vera (moisturizer), Henna (hair dye), Neem and Turmeric (antiseptic), Amla and Shikakai (hair care), Sandalwood (skin).

Which crude drugs/volatile oils are major items of Indian and worldwide trade?

Worldwide-traded volatile oils include peppermint, eucalyptus, lemongrass, citronella, sandalwood, clove, and mentha oils. India is a leading exporter of mentha/menthol, lemongrass, sandalwood, and psyllium (Isabgol).

Define crude fibre and total ash as physical evaluation parameters.

Crude fibre is the indigestible cellulosic residue remaining after successive acid and alkali digestion of the drug. Total ash is the inorganic residue (physiological + non-physiological ash) remaining after complete incineration, indicating mineral content and earthy contamination.

What is a chemical race (chemical/geographical variety) and why is it significant in pharmacognosy?

A chemical race is a plant species that is morphologically identical but differs in the type/amount of chemical constituents due to genetics or environment; it is significant because it affects the therapeutic quality and selection of source plants for cultivation.