Pharmacognosy is a key subject in D. Pharmacy, and understanding concepts of different plant and there sources are clearly important than just memorizing. In this post, Pharmacognosy Important questions are explained in simple language, which is useful for MSBTE, AKTU, BTEUP, RUHS and other state boards.
Q1) Understand the Definition, History, Scope, and Present Status Pharmacognosy
Pharmacognosy is a branch of pharmaceutical science that deals with the study of crude drugs obtained from natural sources such as plants, animals, minerals, and microorganisms. It includes identification, authentication, extraction, phytochemical investigation, evaluation, and classification of crude drugs. The term Pharmacognosy was coined by Johann Adam Schmidt in 1811.
The history of pharmacognosy is very old and dates back to ancient civilizations. Early cultures such as Egypt, India, China, and Nepal used natural substances for treating diseases. Egyptians possessed advanced knowledge of medicinal plants and human anatomy. In Greece, Hippocrates, known as the Father of Medicine, emphasized the use of natural remedies. Galen, a Greek pharmacist, contributed significantly by describing methods for preparing medicines from plants. In India, medicinal plant use dates back to 3500 BC. The Rigveda and Atharvaveda mention several medicinal plants. Ayurveda provides detailed descriptions of drugs and therapies, and important texts like Charaka Samhita and Sushruta Samhita were written by Charaka and Sushruta.
The scope of pharmacognosy is wide. It plays a major role in the crude drug industry, including collection, drying, storage, and marketing of crude drugs. Phytochemistry deals with isolation and identification of chemical constituents such as alkaloids, glycosides, tannins, volatile oils, and resins. Quality control ensures purity and identity using microscopy, chemical tests, physical constants, and biological assays. Pharmacognosy also supports herbal drug formulation and the use of biotechnology such as plant tissue culture for production of active compounds.
At present, pharmacognosy has gained global importance due to the increasing demand for herbal medicines with fewer side effects. WHO encourages the use of natural medicines. There is rapid growth in nutraceutical, cosmeceutical, and phytopharmaceutical industries. Advanced analytical techniques like HPLC, GC-MS, and spectrophotometry are widely used, and herbal drugs are accepted globally.
Q2) Adulteration of Crude Drugs is very important exam topic
Adulteration is the substitution of original crude drugs wholly or partially with other substances that resemble the genuine drug but are inferior in quality, purity, or therapeutic value.
One common method is substitution with manufactured materials, where artificial substances similar in appearance are used, such as yellow-coloured paraffin wax in place of beeswax.
Another method is substitution with inferior materials, where low-grade drugs are mixed with genuine ones, for example mother cloves mixed with cloves and safflower flowers used instead of saffron. Substitution with exhausted materials involves using drugs from which active constituents have already been removed, such as exhausted ginger or clove and Arabian senna substituted for Alexandrian senna. Cheap natural substances may also be used, like Japan wax for beeswax and Sterculia gum for tragacanth. Sometimes non-plant materials such as stones, sand, soil, or chalk are added to increase weight or bulk.
Q3) Evaluation of Crude Drugs is also very important exam topic for practical and theory exam
Evaluation of crude drugs is done to determine quality, purity, and to detect adulteration. Whole drugs are evaluated using morphological features, powdered drugs by microscopic examination, and liquid drugs using physical and chemical parameters.
Physical evaluation includes determination of properties such as specific gravity, density, refractive index, melting point, viscosity, solubility, and optical rotation, which help confirm identity and purity.
Chemical evaluation involves qualitative tests and quantitative assays for estimation of active constituents, along with values like acid value and saponification value. Biological evaluation, also called bioassay, determines drug potency by comparing its effect on living organisms with a standard. Morphological or organoleptic evaluation involves observing colour, odour, taste, size, shape, texture, and sound, which is useful in detecting adulteration. Microscopic evaluation is mainly used for powdered and organized drugs and involves identification of tissues and cells under a microscope using specific reagents.
Q4) Understanding about Alkaloids is very crucial
Alkaloids are basic nitrogen-containing organic compounds of plant origin that show physiological activity. They contain one or more nitrogen atoms and exhibit basic properties similar to alkalis.
Alkaloids are classified into true alkaloids, proto alkaloids, and pseudo alkaloids. True alkaloids contain heterocyclic nitrogen and are derived from amino acids, such as quinine, atropine, and morphine. Proto alkaloids do not contain nitrogen in a heterocyclic ring, for example ephedrine. Pseudo alkaloids contain heterocyclic nitrogen but are weakly basic, such as caffeine.
Alkaloids occur mainly in plants and are commonly found in seeds, bark, roots, leaves, and fruits. They are more abundant in dicotyledonous plants. Families rich in alkaloids include Solanaceae, Papaveraceae, Rubiaceae, and Apocynaceae.
Isolation of alkaloids is commonly done by the Stas-Otto process, where alkaloids are liberated using alkali and extracted with organic solvents. In the Kippenberger process, powdered drug is digested with tannin solution in glycerol at controlled temperature followed by separation of alkaloids. Identification tests include Dragendorff’s test, Mayer’s test, Hager’s test, and Wagner’s test, each producing characteristic precipitates. Alkaloids are used as antidepressants, local anaesthetics, antiseptics, and antibacterial agents.
Q5) Volatile Oils is also way more important topic in pharmacognosy
Volatile oils are aromatic, volatile substances of plant or animal origin that evaporate at ordinary temperature. They are also called essential oils.
Volatile oils are classified based on their chemical nature. Hydrocarbon oils include turpentine. Aldehyde oils include lemongrass and cinnamon. Alcohol oils include peppermint. Ketone oils include camphor and cumin. Phenolic oils include clove, while oxide oils include cardamom.
Volatile oils are mainly found in plants and occur in specialized secretory structures such as oil glands, oil ducts, oil cells, and glandular trichomes. In some plants, volatile oils are produced by enzymatic breakdown of glycosides, as seen in mustard oil.
Isolation methods include distillation using Clevenger apparatus for drugs like clove and sandalwood, expression method for citrus fruits, solvent extraction using ether or petroleum ether, and maceration mainly for flowers. Identification tests include Sudan III test, which shows red-coloured globules, and tincture iodine test, which produces red colour. Volatile oils are widely used as antiseptics, antispasmodics, carminatives, flavouring agents, spices, and in the perfume industry.
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