Pharmacognosy and Phytochemistry of Crude Drugs

Posted on Feb 14, 2026 in Biology

Cardiotonic Drugs and Cardiac Glycosides

Definition: Cardiotonic drugs are substances that increase the force of myocardial contraction and improve heart function. They are primarily used to treat cardiac insufficiency and heart failure, and they typically contain cardiac glycosides.

Examples and Biological Sources

• Digitalis: Obtained from the dried leaves of Digitalis purpurea. Use: Enhances cardiac contraction.
• Strophanthus: Obtained from the seeds of Strophanthus kombe. Use: Strengthens heart pumping action.

Rauwolfia: Indian Snakeroot

Biological Source: Rauwolfia consists of the dried roots of the plant Rauwolfia serpentina, belonging to the family Apocynaceae. It is commonly known as Indian Snakeroot or Sarpagandha.

Chemical Constituents

Rauwolfia contains mainly indole alkaloids. Important alkaloids include:

• Reserpine
• Ajmaline
• Ajmalicine
• Serpentine

Therapeutic Uses

• Used as an antihypertensive to lower high blood pressure.
• Acts as a sedative and tranquilizer to calm the mind.
• Helps in treating anxiety and insomnia.
• Historically used for mental disorders.
• Traditionally used for snake bites.

Chemical Evaluation of Crude Drugs

Chemical evaluation determines the chemical nature and quantity of active constituents within a drug.

Methods of Chemical Evaluation

1. Precipitation Reactions: For example, testing for alkaloids using Mayer’s reagent.
2. Color Reactions: For example, the Keller–Killiani test for cardiac glycosides.
3. Chromatography: Used for the separation and identification of constituents.
4. Titration Method: Used for the determination of alkaloid content.
5. Spectroscopic Methods: Utilizing UV, IR, and NMR for structure elucidation.

Classification of Crude Drugs

Crude drugs are classified using several methods to facilitate study and identification.

A. Based on Source

• Plant Drugs: Senna, Clove, Ginger.
• Animal Drugs: Honey, Cod liver oil.
• Mineral Drugs: Kaolin, Talc.
• Marine Drugs: Agar, Sponge.

B. Based on Chemical Nature

• Alkaloids: Belladonna, Rauwolfia.
• Glycosides: Digitalis, Senna.
• Tannins: Catechu.
• Volatile Oils: Clove, Eucalyptus.

C. Based on Therapeutic Use

• Laxatives: Senna, Castor oil.
• Analgesics: Opium.
• Antimalarials: Cinchona.
• Carminatives: Ginger, Clove.

Isolation Process of Glycosides

Isolation involves separating glycosides from plant material to obtain them in a pure form.

Steps in the Isolation Process

1. Collection and Drying: Plant parts (leaves, roots, bark) are collected and dried.
2. Grinding: The dried drug is powdered to increase the surface area for extraction.
3. Extraction: The powder is extracted using water, alcohol, or hydro-alcohol based on solubility.
4. Removal of Impurities: The extract is filtered to remove fats, waxes, chlorophyll, and tannins.
5. Hydrolysis (if needed): Separating the glycone (sugar part) from the aglycone (non-sugar part).
6. Isolation and Crystallization: The purified glycoside is crystallized into a solid form.
7. Drying and Storage: Stored in airtight containers to protect from moisture and light.

Biological Source and Uses of Key Drugs

Senna

• Source: Dried leaflets and pods of Cassia angustifolia.
• Constituents: Anthraquinone glycosides (sennosides A–D).
• Uses: Mild laxative for constipation.

Clove

• Source: Dried flower buds of Syzygium aromaticum.
• Constituents: Volatile oil (eugenol).
• Uses: Antiseptic, carminative, and toothache relief.

Cinchona

• Source: Bark of Cinchona species.
• Constituents: Alkaloids (quinine, quinidine).
• Uses: Antimalarial and cardiac regulation.

Ginger

• Source: Rhizomes of Zingiber officinale.
• Constituents: Volatile oils, gingerol.
• Uses: Anti-emetic, digestive stimulant, and anti-inflammatory.

Rauwolfia (Summary)

• Source: Roots of Rauwolfia serpentina.
• Constituents: Alkaloids (reserpine, ajmaline).
• Uses: Antihypertensive and sedative.

Phytochemistry: Importance and Scope

Phytochemistry is the study of chemicals produced by plants, such as alkaloids, glycosides, tannins, and terpenoids.

Importance of Phytochemistry

• Identifies active medicinal compounds.
• Ensures purity and quality of herbal drugs.
• Assists in isolation and standardization.
• Supports drug discovery and formulation.

Scope of Phytochemistry

• Herbal medicine development.
• Nutraceuticals and supplements.
• Standardization of crude drugs.
• Research in pharmaceutical sciences.

Stomatal Number and Index

• Stomatal Number: The total number of stomata per square millimeter of leaf surface.
• Stomatal Index: The proportion of stomata compared to the total number of epidermal cells.
• Use: Helps in the identification of powdered crude drugs.

Significance of Ash Values

Ash values represent the amount of inorganic residue remaining after burning a crude drug.

Importance

• Indicates drug purity.
• Detects adulteration with earthy or chalky matter.
• Assists in standardization.

Types of Ash Values

• Total ash
• Acid-insoluble ash
• Water-soluble ash
• Sulphated ash

Nutraceuticals: Definition and Examples

Definition: Nutraceuticals are food or plant-derived products that provide health benefits beyond basic nutrition, aiding in disease prevention or management.

Examples of Nutraceuticals

• Garlic: Reduces cholesterol.
• Omega-3 Fatty Acids: Supports heart health.
• Probiotics: Improves gut health.
• Green Tea Extract: Acts as an antioxidant.
• Spirulina: Nutritional supplement.

Ipecacuanha: Source and Constituents

• Source: Dried roots of Cephaelis ipecacuanha.
• Constituents: Alkaloids (emetine, cephaeline).
• Uses: Expectorant in small doses, emetic in higher doses, and treatment for amoebic dysentery.

Alkaloids: Definition and Classification

Definition: Alkaloids are basic nitrogenous organic compounds, mostly plant-derived, that exhibit physiological activity.

Classification Based on Origin

1. True Alkaloids: Contain nitrogen in a heterocyclic ring (e.g., Morphine, Atropine).
2. Proto Alkaloids: Nitrogen is not in a ring (e.g., Ephedrine).
3. Pseudo Alkaloids: Derived from non-amino acid precursors (e.g., Caffeine).

General Uses: Analgesic, stimulant, antimalarial, and antihypertensive.

Adulteration of Crude Drugs

Definition: Adulteration is the practice of lowering the quality of a crude drug by adding similar-looking or cheaper substances, reducing its medicinal value. This can be intentional or accidental.

Types of Adulteration

1. Substitution: Replacing the original drug with a cheaper alternative.
2. Inferior Quality: Using old, damaged, or spoiled drugs.
3. Artificial Adulteration: Adding harmful chemicals, colors, sand, or chalk.
4. Sophistication: Mixing non-useful parts of the same plant.
5. Accidental Adulteration: Contamination by insects, fungi, or misidentification.
6. Admixture: Mixing unwanted plant parts during harvesting.

Glycosides and Identification Tests

Definition: Glycosides are organic compounds where a sugar part (glycone) is attached to a non-sugar part (aglycone). They possess various medicinal activities.

Identification Tests

• Cardiac Glycosides: Keller–Killiani Test (Blue-green color).
• Anthraquinone Glycosides: Borntrager’s Test (Pink to red color in alkaline solution).
• Saponin Glycosides: Foam Test (Persistent foam formation).
• Cyanogenic Glycosides: Guignard Test (Reddish-brown color).

Surgical Fibers: Types and Properties

Definition: Surgical fibers are used in medical work for sutures, dressings, and bandages. They must be biocompatible.

Sources and Types

• Natural Surgical Fibers: Obtained from plants or animals (e.g., Cotton, Silk, Linen).
• Synthetic Surgical Fibers: Man-made (e.g., Nylon, Polyester, Polypropylene).

Properties of Surgical Fibers

1. Sterile and free from germs.
2. Strong and durable.
3. Flexible and easy to handle.
4. Non-toxic and non-irritant.
5. Non-allergenic.
6. Should not support microbial growth.

Uses

• Sutures for stitching wounds.
• Dressings and pads for fluid absorption.
• Bandages for support and protection.