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📚 PHARMACOGNOSY NOTES

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🌸 CROCUS (SAFFRON)

Basic Identification

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Cultivation & Collection

• Plants raised from corms (bulb-tuber) planted during July/August
• Flowering takes about one year
• Flowers collected in early morning in November and December
• Stigmas and upper style portions are detached manually
• Drug dried by artificial heat and stored in dry place
• India's share in global supply = 50 tonnes (~10% of world requirement)
• About 5000 hectares of land under cultivation in Kashmir and Himachal Pradesh

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Macroscopic Characters

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Chemical Constituents

• Red colouring matter: Crocin and Crocetin
• Bitter principle: Picrocrocin
• Traces of volatile oil
• Protocrocin (a carotenoid glycoside) splits on drying into:
  • 2 molecules of Picrocrocin + 1 molecule of Crocin
• Crocin hydrolyses → Crocetin + Gentiobiose
• Picrocrocin yields → Glucose + Safranal
• Yields 50-60% extractives to cold water
• Crocin gives blue colour with concentrated sulphuric acid

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Chemical Test

• Add a drop of sulphuric acid to dry stigma
• Turns blue → purple → purplish-red
• Saffron imparts yellowish-orange-brown colour to water

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Uses

• Colouring agent (food dye)
• Flavouring agent
• Antispasmodic
• Emmenagogue
• Stimulant

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Substitutes & Adulterants

• Adulterated due to high price
• Common adulterant: florets of Safflower (Carthamus tinctorius Linn, family Compositae) - orange in colour
• Safflower florets → impart orange colour to alcohol (authentic drug = NO colour)
• Weight increased by adding glycerin and ammonium nitrate
• Detected by determining water-soluble extractive

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🌲 TAXUS (YEW)

Basic Identification

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Important Species

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Geographical Source

• Very slow growing, evergreen gymnospermous tree
• Found in India, Canada, America
• Reported in temperate Himalayan region of India
• Altitude: 2000-3500 metres

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Morphological Characters

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Chemical Constituents

• Main constituent: Paclitaxel (Taxol) - present in all parts, especially leaves, roots, bark
• Taxanes = most important group; 40 different taxane compounds found (all diterpenoid structures)
• Three most important members:
  1. Taxol
  2. Cephalomanine
  3. 10-Deacetyl baccatin
• Taxol concentration: 0.007% to 0.01%
• Mainly obtained from stem bark of T. brevifolia

Key Potent Compounds:

• Taxol (contains rare oxetane ring end amide side chain)
• Cephalomanine (0.031%)
• Baccatin-III (0.084%)
• 10-Deacetyl baccatin III

Taxotere:

• Derivative of Taxol
• Better bioavailability and pharmacological properties
• Promising anticancer agent

Yield Data:

• Needs ≥60 year-old trees (3-4 trees) to get 1 gm of Taxol
• 50-150 mg Taxol from 1 kg dried yew bark
• ~10 kg bark from one average tree
• Leaves contain 10-deacetyl baccatin III → easily converted to Taxol

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Uses

• Anticancer ⭐ (approved by USFDA for refractory ovarian cancer)
• Analgesic
• Anti-inflammatory
• Antipyretic
• Anticonvulsant

Mechanism of Action:

• Biological target: microtubules (produced from α and β-tubulin)
• Taxol promotes polymerization of microtubules even in absence of MAP (microtubule associated proteins) and GTP
• Enhanced microtubule formation → detrimental effects on dividing cells → blockade of cell cycle
• Multiple abnormal esters formed from microtubules → distributed in cytoplasm

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🌰 ANNATTO

Basic Identification

• Peru meets ~40% of world requirement
• India contributes only 10%

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Macroscopic Characters

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Cultivation & Collection

• Sown from seeds or cuttings
• Needs tropical setting in loamy soil at altitude of 1000 metres
• Plant height: 2-6 metres; survives for 50 years
• Bears prickly heart-shaped pods; each pod bears ~50 seeds

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Preparation for Market

• Bixa commercially grown for dye and spice
• Matured prickly pods collected and dried
• Fruits macerated in water → dye settles → collected, dried → made into cakes
• Seeds from pulp separated and washed for further processing

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Chemical Constituents

• Seeds covered with aril (extra seed covering) containing bixin dye
• Contain 12% annatto oleo resin (50% water soluble)
• Volatile oil: only 0.3-0.8%
• Pigments: 4-5%
• Main pigment constituent: Bixin (~70-80% of pigment)
• Bixin = carotenoid carboxylic acid → responsible for yellow colour
• Other isomers: Isobixin, trans-bixin, nor-bixin
• Bixin naturally in cis-form → converts to trans-bixin during extraction
• Pure Bixin: insoluble in water, soluble in organic solvents and alkaline aqueous solutions
• Bixin = monomethyl ester of nor-bixin (a dicarboxylic acid) → gets hydrolyzed to dicarboxylic acid

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Quick Revision Tip: Remember the 3 drugs - Crocus (stigma, Iridaceae, Crocin), Taxus (bark/leaves, Taxaceae, Taxol/Paclitaxel), Annatto (seeds, Bixaceae, Bixin)