PHYTOCHEMICAL CONSTITUENTS OF CRUDE DRUGS
Natural products found in crude drugs contain a wide range of chemical compounds known as phytochemicals. Among them, alkaloids, terpenoids, glycosides, volatile oils, tannins, and resins are some of the most important groups. These compounds are responsible for the therapeutic properties of many medicinal plants. Below is a brief outline of their occurrence, distribution, isolation, identification tests, therapeutic activities, and pharmaceutical applications.
Alkaloids
Occurrence and Distribution
Alkaloids are nitrogen-containing compounds widely found in plant families such as Solanaceae, Papaveraceae, Rubiaceae, and Apocynaceae.
Isolation
- Extraction with organic solvents
- Acid-base extraction method
- Solvent partition techniques
Identification Tests
- Dragendorff’s test – Orange precipitate
- Mayer’s test – Cream precipitate
- Wagner’s test – Reddish-brown precipitate
Therapeutic Activity
Alkaloids exhibit analgesic, antimalarial, anticancer, antispasmodic, and cardiotonic properties.
Pharmaceutical Applications
Common alkaloid drugs include morphine, quinine, atropine, and reserpine.
Terpenoids
Occurrence and Distribution
Terpenoids occur in essential oils, resins, and oleo-gum resins of plants like eucalyptus, mentha, and citrus.
Isolation
- Steam distillation
- Solvent extraction
- Supercritical CO₂ extraction
Identification Tests
- Salkowski test – Red color
- Liebermann–Burchard test – Green/blue
Therapeutic Activity
Antimicrobial, anti-inflammatory, anticancer, bronchodilator, hepatoprotective.
Glycosides
Found in Digitalis, Senna, Aloe, Rauwolfia.
- Keller-Killiani test
- Borntrager’s test
- Legal test
Used as cardiotonics, laxatives, anti-inflammatory agents.
Volatile Oils
Found in cinnamon, peppermint, clove, eucalyptus.
- Steam distillation
- Cold pressing
- Solvent extraction
Used as antiseptic, expectorant, carminative.
Tannins
Polyphenolic compounds in tea, amla, cinchona.
- Ferric chloride test
- Gelatin test
Used as astringent, antimicrobial.
Resins
Non-volatile plant exudates.
- Solubility test
- Heat test
Used in ointments, adhesives, plasters.
Dr. Saint Paul is a pharmacy educator, Pharm.D graduate, and academic content creator from Jawaharlal Nehru Technological University Kakinada (JNTUK), where he completed his Doctor of Pharmacy (Pharm.D) degree between 2015 and 2021.
He has more than 7 years of experience creating pharmacy educational content, writing study materials, and reviewing academic articles for pharmacy students. He has also contributed guest articles to pharmacy education platforms, including PharmD Guru.
At D.PharmGuru, his work focuses on simplifying complex Diploma in Pharmacy (D.Pharmacy) subjects into easy-to-understand notes, practical explanations, and exam-oriented educational resources for students across India.
His areas of focus include Human Anatomy and Physiology, Pharmaceutics, Pharmacology, Pharmaceutical Chemistry, Hospital and Clinical Pharmacy, and other core D.Pharmacy subjects.
