Definition of Drug
A drug is any substance that, when administered into the body, alters its physiological functions.
This alteration can be therapeutic (as in the case of medicine) or harmful (as in toxins). Drugs can
be natural, semi-synthetic, or synthetic in origin. Natural drugs, in particular, are derived from
plant, animal, or mineral sources and have been used for centuries for their medicinal properties.
Classification of Natural Drugs
Natural drugs can be classified based on various systems. Each classification method has its own
significance in the study and identification of natural drugs.
1. Alphabetical Classification
This system arranges drugs alphabetically by their botanical or common names. It’s widely used
in pharmacopoeias and reference books for quick and systematic retrieval of information.
Example:
• A: Aloe, Aconite
• B: Belladonna, Balsam
• C: Cinchona, Colchicum
2. Morphological Classification
Morphological classification is based on the part of the plant from which the drug is derived. Each
part of the plant may have different medicinal properties. Key categories include:
• Leaves: Example: Senna leaves (used as a laxative)
• Flowers: Example: Chamomile (used for digestive problems)
• Fruits: Example: Fennel (used to treat bloating and digestion issues)
• Seeds: Example: Fenugreek (used to control diabetes and cholesterol)
• Roots: Example: Ginseng (used as a tonic to improve stamina)
• Bark: Example: Cinchona (source of quinine, used to treat malaria)
• Wood: Example: Ephedra (used to treat asthma and bronchitis)
3. Pharmacological Classification
This classification is based on the drug’s therapeutic action or pharmacological effect. It organizes
drugs according to the system they act on or the effects they produce:
• CNS Stimulants: Example: Cocaine, Caffeine
• CNS Depressants: Example: Opium, Belladonna
• Cardiovascular Drugs: Example: Digitalis (used to treat heart diseases)
• Antimalarial Drugs: Example: Quinine from Cinchona
• Antiasthmatic Drugs: Example: Ephedrine from Ephedra
4. Chemical Classification
This classification is based on the chemical nature of the active constituents in the drug. Natural
drugs contain various phytochemicals that are categorized into groups like alkaloids, glycosides,
tannins, etc.:
• Alkaloids: Example: Morphine (from opium poppy), Quinine (from Cinchona)
• Glycosides: Example: Digitalis glycosides (used in heart failure)
• Tannins: Example: Witch hazel (used in treating skin irritations)
• Terpenoids: Example: Menthol (from peppermint)
Traditional and Folklore Medicine
Traditional medicine refers to health practices, approaches, and knowledge systems that are
culturally rooted and have been passed down over generations. These systems often involve the
use of natural drugs derived from plants, animals, and minerals. Folklore medicine, a subset of
traditional medicine, includes practices specific to a community's culture and history.
• Ayurveda: Traditional Indian medicine using plants like Ashwagandha (to promote
strength and vitality).
• Unani: Uses Ginger for digestive issues.
• Traditional Chinese Medicine: Employs Ginseng to boost energy.
• African Traditional Medicine: Utilizes Kigelia (sausage tree) for skin ailments.
Native Medicine Drugs from Various Plant Parts
The effectiveness of traditional remedies often comes from different parts of the plant, each of
which has specific bioactive compounds.
1. Leaves
Leaves are a common source of drugs due to their rich phytochemical content:
• Senna (Senna alexandrina): Used as a laxative, the active compounds are anthraquinone
glycosides.
• Neem (Azadirachta indica): Widely used for its antiseptic properties.
2. Flowers
Flowers contain essential oils and other active constituents:
• Chamomile (Matricaria chamomilla): Contains flavonoids and terpenoids; used for its
calming and anti-inflammatory effects.
• Clove (Syzygium aromaticum): Clove buds (flower part) are used for their antimicrobial
properties.
3. Fruits and Seeds
Many fruits and seeds are valued for their medicinal properties:
• Fennel (Foeniculum vulgare): The seeds are used for digestive disorders.
• Castor (Ricinus communis): Castor oil, extracted from seeds, is used as a purgative.
4. Roots
Roots often contain potent alkaloids, glycosides, and other active ingredients:
• Ginseng (Panax ginseng): Known for its adaptogenic properties, it enhances energy levels
and stress resistance.
• Licorice (Glycyrrhiza glabra): The root is used for treating sore throat and cough.
5. Bark
The bark of trees often stores alkaloids and other compounds:
• Cinchona Bark (Cinchona officinalis): The source of quinine, a well-known antimalarial
compound.
• Willow Bark (Salix alba): The source of salicylic acid, the precursor to aspirin.
6. Wood
Wood is less commonly used, but certain plants have medicinal wood:
• Ephedra (Ephedra sinica): Used in traditional Chinese medicine, it is a source of
ephedrine, used for asthma and other respiratory ailments.
• Sandalwood (Santalum album): Known for its soothing and antimicrobial properties,
often used in skin treatments.
Conclusion
Understanding the classification of natural drugs and their use in traditional medicine is essential
for appreciating their therapeutic potential. From the basic alphabetical classification to the more
complex pharmacological and chemical systems, each method provides a unique way to categorize
and study these drugs. Additionally, the use of various plant parts in traditional systems highlights
the rich diversity of natural remedies that continue to play a vital role in modern medicine.
References
1. Trease, G.E., & Evans, W.C. (2009). Pharmacognosy (16th ed.). Saunders Ltd.
2. Kokate, C.K., Purohit, A.P., & Gokhale, S.B. (2010). Pharmacognosy (49th ed.).
3. Tyler, V.E., Brady, L.R., & Robbers, J.E. (1988). Pharmacognosy (9th ed.). Lea &
Febiger.
4. Akos, M. (2015). Medicinal and Aromatic Plants of the World. Springer.
5. WHO (2000). General Guidelines for Methodologies on Research and Evaluation of
Traditional Medicine. World Health Organization.
6. Chevallier, A. (2016). Encyclopedia of Herbal Medicine. DK Publishing.
