JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Pharmacy II Year II Semester PHARMACOGNOSY AND PHYTOCHEMISTRY - I Previous Question Paper (August- 2021 - R17)

Drugs obtained from natural sources are classified based on their biological origin, primarily plants and animals.

Plant Sources: Plants are the most significant source of therapeutic agents. Drugs are derived from various parts of the plant, including:

• Leaves: e.g., Digitalis, Senna, and Eucalyptus.
• Flowers: e.g., Clove, Saffron, and Pyrethrum.
• Fruits: e.g., Fennel, Coriander, and Senna pods.
• Seeds: e.g., Nux vomica, Linseed, and Castor.
• Roots and Rhizomes: e.g., Rauwolfia, Ginger, and Turmeric.
• Barks: e.g., Cinchona and Cinnamon.
• Exudates and Gums: e.g., Acacia, Tragacanth, and Asafoetida.

Animal Sources: Drugs obtained from animals are often complex biological products used for hormonal, nutritional, or enzymatic therapy:

• Glands and Organs: e.g., Thyroid, Pancreas (source of insulin), and Liver (source of liver extract).
• Secretions and Excretions: e.g., Musk, Civet, and Honey.
• Fats and Waxes: e.g., Wool fat (lanolin), Cod liver oil, and Beeswax.
• Enzymes: e.g., Pepsin and Trypsin.

Adulteration is the practice of substituting the original drug with inferior, defective, or harmful substances. Evaluation is critical to ensure quality and safety.

Microscopic Evaluation: This is the most reliable method for identifying powdered drugs or crude sections. It involves:

1. Histological Analysis: Examining the arrangement of tissues, such as xylem, phloem, and vascular bundles, to confirm the identity of the plant part.
2. Quantitative Microscopy: Determining specific values like Stomatal Number, Stomatal Index, Vein-islet Number, and Palisade Ratio. Deviations from standard values indicate adulteration.
3. Powder Analysis: Identifying characteristic features like trichomes, starch grains, calcium oxalate crystals, and fibers using staining reagents (e.g., phloroglucinol and HCl for lignified tissues).

Clinical/Biological Evaluation: This involves testing the drug's activity on living organisms to verify its therapeutic efficacy, which is often used when chemical or physical methods are insufficient:

1. Bioassays: Measuring the pharmacological effect of the drug on isolated tissues or whole animals (e.g., the effect of digitalis on the heart of a frog or cat).
2. Toxicity Testing: Assessing the presence of harmful contaminants or unexpected side effects in animal models.
3. Microbiological Assays: Used primarily for antibiotics and vitamins to determine the potency of the drug by observing the inhibition of microbial growth.