Eighteen years ago, I made a significant decision to resign from my role as a community pharmacist. I felt that stepping away from the conventional pharmacy setting would open doors to better opportunities and allow me to explore what it truly means to be a pharmacist.

Soon after, a college classmate invited me to work in a different setting. Initially, I was skeptical, as this new role was quite different from my previous job. But, I submitted my curriculum vitae and the rest is history. Today, I continue to work in a company focused on alternative healing methods that improve patient’s quality of life.

During my college years, one of my favorite subjects was Pharmacognosy. This term is derived from the Greek words pharmakon (drug) and gnosis (knowledge). Pharmacognosy is the study of medicines obtained from the natural sources such as medicinal plants, animals, minerals and microbes.

A key part of pharmacognosy is the classification of plant- derived substances based on their chemical nature. These active constituents are responsible for the therapeutic effects of crude drugs. Classifying them systematically helps in identifying, isolating and utilizing these substances for medicinal use.

The Father of Pharmacognosy, Pedanuis Dioscorides, a Greek physician, who wrote the De Materia Medica, a collection of knowledge of properties and applications of medicinal substances. It also serves as a reference book in homeopathy.

In college, I am fond of creating detailed tables of medicinal plants, listing their scientific names, genus, species, family names, chemical classifications, active constituents and pharmacological effect.

Example of medicinal plant:

Scientific name: Allium sativum

Common name: garlic

Family: Amaryllidaceae

Classification: Volatile oil

Active constituent: Allicin

Uses: Antibacterial, antiviral, lowers blood pressure.

In Writing Scientific Name

The first word is the genus name and it always start with a capital letter. The second word is the species name and it is written in lower case. Both words are written in italics, while the family name is written separately but it is not italicized and usually ends up with acaeae.

Plants produce a variety of chemical substances, many of which have the therapeutic properties. In pharmacognosy, these active compounds are classified based on their chemical structure and nature, active constituents and pharmacological significance. Understanding these classes help us appreciate how different natural substances contribute to the therapeutic effects of medicines.

Major Chemical Classes of Plant – Derived Compounds

1. Glycosides are a class of compounds in which a sugar moiety(glycone) is chemically linked to a non sugar component(aglycone or genin). The nature of the aglycone determines the pharmacologic activity of the glycosides.

Examples:

•Cardiac glycosides – from Digitalis purpurea

Active constituents: Digoxin, Digitoxin

Uses: Cardiotonic

•Anthraquinone glycosides – from Aloe vera

Active constituent: Aloin

Uses: Laxative, wound healing, skin condition

•Saponin glycosides – from Glycyzzrhiza glabra

Active constituent: Glycyrrhizin

Uses: Anti-inflammatory, food and cosmetics additive

2. Alkaloids are diverse group of nitrogen containing organic compounds mostly derived from amino acids. They are often basic in nature and exhibit strong physiological effects, making them among the most pharmacologically potent plants constituents.

Examples:

•Morphine, codeine – from Papaver somniferum ( opium poppy)

Uses: Analgesic

•Quinine – from Cinchona species

Uses: Anti-malarial

•Atropine, Scopolamine – from Atropa belladonna

Uses: Antispasmodic

3. Tannins are class of high molecular weight of polyphenolic compounds commonly found in various plant parts such as bark, leaves and fruits. Tannins are known for its astringent properties due to their ability to precipitate proteins. This property makes them useful in the treatment of diarrhea, bleeding and inflammation.

Tannins are classified into two main types :

1. Hydrolysable Tannins- yields gallic or ellagic acid upon hydrolysis

Example:

•Tannic acid – from gall nuts

Uses: Clarifying agent in winemaking, antidiarrheal, treatment of rashes and minor burns

• Ellagic acid – from fruits and nuts

Uses: Dermatological products and dietary supplements

2. Condensed Tannins- also known as proanthocynanidins, which are polymers of flavanoids units.

Example:

•catechins – found in tea, beans, cocoa, grapes

Uses: Antioxidant, cholesterol and weight management, anti-inflammatory

4. Volatile Oils (Essential Oils ) are mixtures of aromatic volatile compounds typically composed of terpenes and their oxygenated derivatives. These oils are responsible for the characteristic aroma among plants.

Examples:

•Eugenol – from Syzygium aromaticum (clove oil)

Uses: Analgesic, anti-inflammatory

• Menthol – from Mentha piperita (peppermint oil)

Uses: Analgesic, food additive, respiratory ailments

5. Resins are amorphous, solid or semi solid substances that are usually insoluble in water but soluble in organic solvents. They may occur naturally or be produced by plants as exudates.

Examples:

•Ferulic acid – from oats, wheats

Uses: Anti oxidant, anti -inflammatory, anticancer, neuroprotective, cardioprotective.

•Umbelliferone – from carrots, coriander, Asafeotida

Uses: Sunscreen agents, anti-inflammatory, antioxidant

6. Gums and Mucilages

These are polysacchharide compounds that swell in water to form viscous gels. Gums are pathological plant exudates formed due to injury, while mucilages are normal metabolic products.

Example:

•Acacia gum – composed mainly of arabinogalactan

Uses: Stabilizer and emulsifier

•Tragacanth- contains bassorin and tragacanthin

Uses: Stabilizer, emulsifying agent, binding agent

7. Carbohydrate an Sugars

These are primary plant metabolites used as energy sources and in pharmaceutical preparations. They are used as excipients or supportive agents in formulations.

Examples:

• Honey – nutritional and anti-microbial properties

• Starch – binding agent

8. Lipid and Fixed Oils

These are non volatile, greasy substances obtained from plant seeds and fruits. They do not evaporate and are composed of fatty acids and glycerides.

Example:

•Castor oil – from Ricinus communis

Uses: laxative

• Coconut oil – from Cocos nucifera

Uses: Cosmetics, antibacterial, antiviral, antifungal

9. Proteins and Enzymes

These are complex nitrogenous compounds with high molecular weight, essential for biological function. Some plant derived enzymes are used therapeutically or industrially.

Example :

•Papain – from Carica papaya

Uses: Digestive disorder, meat tenderizer

10. Phenolic compounds and Flavanoids

These are aromatic compounds with one or more hydroxyl group. Flavanoids are subgroup of phenolics, that are widely distributed in plants.

Examples:

• Curcumin – from Curcumin longa(Turmeric)

Uses: Anti-inflammatory and antioxidant properties

Pharmacognosy’s Role in Modern Therapeutics

Pharmacognosy not only deepens our understanding of plant derived medicines but also forms the foundations for complementary therapeutic system like homeopathy and homotoxicology.

For example, Atropa belladonna and Arnica montana are studied for its alkaloid but are also used in highly diluted forms in homeopathic medicines to stimulate body’s natural healing processes.

In my next article, I will explore these fascinating fields, principles and applications, and how they integrate with modern science.

On the other hand, Homotoxicology, is an alternative medicine that combines the elements of homeopathy and toxicology. Developed by a German physician named Hans-Heinrich Reckeweg in the mid 20th century, it uses complex formulation with low potency to enhance biological signaling and reduce toxic load.

Thus, pharmacognosy bridges traditional herbal knowledge with modern pharmacological science, supporting drug discovery, standardization, and new gentle therapeutic approaches.