Phytochemical Analysis: Alkaloids, Oils, and Glycosides

Posted on Feb 18, 2026 in Pharmacy

Phytochemical Classes and Tests

Alkaloids

  • Definition: Nitrogen-containing compounds, often basic, found in plants.
  • Classification: Based on structure (e.g., pyrrolidine, quinoline) or source (e.g., opium, Cinchona alkaloids).
  • Chemical Tests: Dragendorff’s reagent, Mayer’s reagent.

Volatile Oils

  • Definition: Odorous, volatile compounds in plants (e.g., essential oils).
  • Classification: Terpenes, aldehydes, esters, etc.
  • Chemical Test: Stain test with Sudan III yields a reddish stain.

Tannins

  • Definition: Polyphenolic compounds that bind proteins, often astringent.
  • Classification: Hydrolyzable, condensed tannins.
  • Chemical Test: Ferric chloride test.

Note: The original text contained an incomplete definition/test sequence for Tannins, which has been corrected by focusing on the established class properties.

Glycosides

  • Definition: Compounds with a sugar moiety linked to a non-sugar part (aglycone).
  • Classification: Based on sugar or aglycone (e.g., cardiac, anthraquinone glycosides).
  • Chemical Test: Molisch’s test: Purple ring with α-naphthol and H₂SO₄.

Prominent Phytochemical Sources and Uses

Alkaloid-Containing Drugs

  1. Vinca (Catharanthus roseus)
    • Source: Leaves of Catharanthus roseus (Apocynaceae).
    • Chemical Constitution: Vinblastine, vincristine (indole alkaloids).
    • Use: Anticancer, leukemia, Hodgkin’s lymphoma treatment.
  2. Rauwolfia (Rauwolfia serpentina)
    • Source: Roots of Rauwolfia serpentina (Apocynaceae).
    • Chemical Constitution: Reserpine (indole alkaloid).
    • Use: Antihypertensive, antipsychotic.
  3. Opium (Papaver somniferum)
    • Source: Latex of Papaver somniferum (Papaveraceae).
    • Chemical Constitution: Morphine, codeine (alkaloids).
    • Use: Analgesic, antitussive.
  4. Clore (Cloroxylon swietenia)
    • Source: Bark of Cloroxylon swietenia (Rutaceae).
    • Chemical Constitution: Chloroxylonine (alkaloid).
    • Use: Antimalarial, antifever.

Saponins and Other Compounds

  1. Liquorice (Glycyrrhiza glabra)
    • Source: Roots of Glycyrrhiza glabra (Fabaceae).
    • Chemical Constitution: Glycyrrhizin (triterpenoid saponin).
    • Use: Expectorant, anti-inflammatory, treats ulcers.

Cardiac Glycosides

  1. Digitalis (Digitalis purpurea)
    • Source: Leaves of Digitalis purpurea (Plantaginaceae).
    • Chemical Constitution: Digoxin, digitoxin (cardenolide glycosides).
    • Use: Heart failure, atrial fibrillation treatment.

Volatile Oils and Resins

  1. Cinnamon (Cinnamomum verum)
    • Source: Bark of Cinnamomum verum (Lauraceae).
    • Chemical Constitution: Cinnamaldehyde (volatile oil).
    • Use: Carminative, digestive aid, antimicrobial.
  2. Guggul (Commiphora mukul)
    • Source: Resin of Commiphora mukul (Burseraceae).
    • Chemical Constitution: Guggulsterones (steroids).
    • Use: Anti-inflammatory, lipid-lowering, arthritis treatment.

Other Important Metabolites

  1. Ajalytida (Ajuga bracteosa)
    • Source: Whole plant of Ajuga bracteosa (Lamiaceae).
    • Chemical Constitution: Ajugarin (diterpenoid).
    • Use: Antimalarial, anti-inflammatory.
  2. Aloy (Aloe vera)
    • Source: Leaves of Aloe vera (Asphodelaceae).
    • Chemical Constitution: Aloin (anthraquinone glycoside).
    • Use: Laxative, skin moisturizer, wound healing.
  3. Senna (Cassia angustifolia)
    • Source: Leaves and pods of Cassia angustifolia (Fabaceae).
    • Chemical Constitution: Sennosides (anthraquinone glycosides).
    • Use: Laxative.
  4. Tannins (Various plants)
    • Source: Various plant parts (e.g., tea, oak bark).
    • Chemical Constitution: Polyphenolic compounds.
    • Use: Astringent, antioxidant, antimicrobial.

Isolation and Analysis of Specific Compounds

Sugar Alcohols and Acids

Mannitol

  • Isolation: Extracted from plants like manna ash using water or ethanol.
  • Identification: TLC, HPLC; appears as a white crystalline powder.
  • Analysis: GC-MS, HPLC; used as an osmotic diuretic.

Glycyrrhetinic Acid

  • Isolation: Hydrolysis of glycyrrhizin from liquorice root extract.
  • Identification: TLC, HPLC; UV-Vis spectroscopy.
  • Analysis: HPLC, LC-MS; used for anti-inflammatory activity.

Alkaloids Isolation

Atropine

  • Isolation: Extracted from Atropa belladonna using ethanol or chloroform.
  • Identification: TLC, HPLC; appears as a crystalline alkaloid.
  • Analysis: GC-MS, HPLC; used as an anticholinergic agent.

Reserpine

  • Isolation: Extracted from Rauwolfia serpentina roots using ethanol.
  • Identification: TLC, HPLC; fluorescence under UV.
  • Analysis: HPLC, LC-MS; used as an antihypertensive.

Other Key Isolates

Curcumin

  • Isolation: Extracted from Curcuma longa rhizomes using solvents like ethanol.
  • Identification: TLC, HPLC; yellow-orange color.
  • Analysis: HPLC, UV-Vis spectroscopy; used for anti-inflammatory activity.

Sennoside Production and Utilization

  • Production: Extracted from Senna (Cassia angustifolia) leaves and pods using solvents like water or ethanol.
  • Utilization: Laxative in pharmaceuticals, used in treating constipation.

Atropine Production and Utilization

  • Production: Extracted from Atropa belladonna or synthesized; often produced via extraction and purification.
  • Utilization: Anticholinergic agent in ophthalmology, anesthesia, and treating bradycardia.

Digoxin Production and Utilization

  • Production: Extracted from Digitalis lanata leaves; purified and standardized.
  • Utilization: Cardiac glycoside for treating heart failure and atrial fibrillation.

Diosgenin Production and Utilization

  • Production: Extracted from Dioscorea species (yams) via acid hydrolysis.
  • Utilization: Precursor for synthesizing steroid hormones (e.g., progesterone) in pharmaceuticals.

Amino Acid Biosynthesis

Amino Acid Biosynthesis Pathways

Amino acids are crucial for protein synthesis, and their biosynthesis involves various pathways.

  • Glycolysis: Produces precursors for Alanine, Valine.
  • Citric Acid Cycle: Links to Glutamate, Glutamine, Proline, Arginine.
  • Shikimic Acid Pathway: Produces Phenylalanine, Tyrosine, Tryptophan.

Regulation: Feedback inhibition, allosteric control. Importance: Essential for protein synthesis, metabolism, and regulation.

Shikimic Acid Pathway Details

  • Description: Metabolic pathway producing aromatic amino acids (Phe, Tyr, Trp) in plants, bacteria, fungi.
  • Key Steps:
    1. PEP + E4P → DAHP
    2. DAHP → Shikimate → Chorismate
    3. Chorismate branches to Phe, Tyr, Trp
  • Importance: Target for herbicides (glyphosate); produces aromatic compounds.
  • Used in: Pharmaceuticals, industrial chemicals.

Phytochemical Separation Techniques

Extraction Methods

Extraction is the process of separating a desired compound or group of compounds from a mixture, typically using a solvent.

Methods of Extraction

  1. Solvent Extraction
    • Maceration: Soaking the material in a solvent.
    • Percolation: Passing a solvent through the material.
  2. Distillation
  3. Cold Pressuring
  4. Pressurized Liquid Extraction
  5. Supercritical Fluid Extraction

Factors Affecting Extraction

  • Solvent choice
  • Temperature
  • Pressure
  • Particle size
  • Extraction time

Spectroscopy Applications

Spectroscopy is the study of the interaction between matter and electromagnetic radiation. It is used to analyze and identify the composition and structure of molecules.

Types of Spectroscopy

  • UV-Vis Spectroscopy
  • IR Spectroscopy
  • NMR Spectroscopy
  • Mass Spectrometry

Applications

  • Identifying compounds
  • Determining molecular structure
  • Quantifying analytes

Chromatography Techniques

Chromatography is a laboratory technique used to separate, identify, and quantify the components of a mixture.

Types of Chromatography

  • Paper Chromatography
  • Thin Layer Chromatography (TLC)
  • Column Chromatography
  • High Performance Liquid Chromatography (HPLC)
  • Gas Chromatography (GC)
  • Adsorption Chromatography
  • Partition Chromatography
  • Ion Exchange Chromatography
  • Size Exclusion Chromatography

Crude Drug Purification and Identification

Purification Methods

  1. Solvent Extraction
  2. Distillation
  3. Chromatography
  4. Crystallization

Identification Methods

  1. Physical Characteristics
  2. Microscopy
  3. Chemical Tests
  4. Chromatography
  5. Spectroscopy