JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D II Year PHARMACOGNOSY AND PHYTOPHARMACEUTICALS Previous Question Paper (July/August - 2021 - R08)

Pesticides are chemical or biological agents, including viruses, bacteria, antimicrobial, disinfectant, or any device, intended for preventing, destroying, attracting, repelling, or mitigating any pest. Pests include insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes, and microbes that compete with humans for food, destroy property, or spread disease.

Pesticides are classified based on the target organism, chemical structure, or mode of action:

• Insecticides: Target insects (e.g., organophosphates, pyrethroids).
• Herbicides: Control unwanted vegetation (e.g., glyphosate, 2,4-D).
• Fungicides: Control fungal growth (e.g., mancozeb, copper compounds).
• Rodenticides: Control rodents (e.g., warfarin).
• Molluscicides: Control snails and slugs.
• Acaricides: Control mites and ticks.

Natural pesticides, also known as biopesticides, are derived from natural materials such as animals, plants, bacteria, and certain minerals. They are generally safer, more biodegradable, and target-specific compared to synthetic alternatives.

Key examples include:

• Pyrethrum: Extracted from the flowers of Chrysanthemum cinerariifolium, it acts as a potent contact insecticide causing rapid knockdown of insects.
• Neem (Azadirachtin): Obtained from Azadirachta indica, it acts as an insect growth regulator, antifeedant, and repellent.
• Nicotine: Extracted from Nicotiana tabacum, it acts as a potent neurotoxin against soft-bodied insects.
• Rotenone: Derived from the roots of Derris species, it functions as a mitochondrial respiratory inhibitor in insects.
• Microbial Pesticides: Such as Bacillus thuringiensis (Bt), which produces proteins toxic to specific insect larvae.

Adulteration is the practice of substituting the original crude drug with a similar-looking, inferior, or harmful substance, or the addition of foreign matter to reduce the quality and potency of the drug. The various methods of adulteration are classified as follows:

1. Substitution with inferior commercial varieties: This involves replacing the genuine drug with another species that is morphologically similar but therapeutically inferior. For example, Capsicum annuum is sometimes substituted with other species of Capsicum that lack the required pungent principles.
2. Adulteration with exhausted drugs: The same drug is used after the active constituents have been extracted. The exhausted material often looks identical to the genuine drug but lacks medicinal value. Examples include exhausted clove or umbelliferous fruits like fennel and coriander, which are mixed with fresh supplies.
3. Addition of foreign matter: This involves the deliberate addition of extraneous materials such as sand, stones, mud, or metallic pieces to increase the weight of the drug. For example, stones are sometimes added to asafoetida, or sand is added to powdered drugs.
4. Adulteration with artificially manufactured substitutes: This involves creating synthetic or artificial materials that mimic the appearance of the genuine drug. For example, paraffin wax is colored yellow and used to adulterate beeswax, or artificial invert sugar is used to adulterate honey.
5. Adulteration with vegetative parts of the same plant: Parts of the same plant that are not therapeutically active are added to the genuine drug. For example, the addition of stem pieces to the leaves of Datura or Senna to increase the bulk.
6. Addition of harmful adulterants: This is a dangerous practice where waste material from other industries is added. For example, limestone pieces are added to asafoetida, or the use of heavy metals like lead to increase the weight of certain roots.
7. Adulteration with synthetic principles: Sometimes, a synthetic chemical is added to a genuine drug to enhance its appearance or mimic the presence of an active constituent. For example, adding citral to oil of lemon to mask poor quality.