Rauwolfia - Source, diagnostic characters, constituents, tests and uses

Rauwolfia

Source, diagnostic characters, constituents, tests and uses

Objectives

At the end of this lecture, student will be able to

• Discuss the source, diagnostic characters, constituents, tests and uses of Rauwolfia

Rauwolfia

Synonym

• Indian snake root, Chootachand, Sarpaganda

Biological Source

• Dried rhizomes and roots of Rauwolfia serpentina contains not less than 0.15 %  of reserpine group of alkaloids, calculated as reserpine

Family

• Apocynaceae

Rauwolfia - Macroscopy

• Size

• Shape

• Colour

• Fracture

• Odour

• Taste

Microscopy

• Periderm

      1. Cork - Stratified

                  - Smaller, suberized, unlignified

                  - Larger, suberized, lignified

      2. Phellogen

      3. Phelloderm

• Secondary phloem

• Secondary xylem

• Medullary rays

            -  Xylem region are lignified

            - Phloem region are not lignified

• Starch and twin prisms of calcium oxalate

Powder characters

Organoleptic characters: Taste, Colour, odour, taste

Active Constituents:

• Alkaloids - Indole alkaloids - Nearly 30 (1.5-3%) - root bark

• Phytosterols, fatty acids, unsaturated alcohols, sugars (dextrose, sucrose)

• Indole alkaloids -

Weakly basic indole group

• Reserpine group- Reserpine, Rescinnamine, desperidine

Tertiary indole alkaloids

• Ajmaline group- Ajmaline, ajmalicine

• Serpentine group- Serpentine, serpentinine, alstonine

Chemical tests:

• Freshly fractured surface with Conc. Nitric acid- red colour in medullary ray

• Vanillin in acetic acid - Violet colour - Reserpine

• Powder + Sulphuric acid in p-dimethyl amino benzaldehyde – violet to red colour (Indole alkaloids)

• Tincture of drug in UV light – blue fluorescence

Uses:

• Treatment of hypertension (Antihypertensive) and in certain neuropsychiatric disorders (Hysteria)

• Treatment of insomnia and certain forms of insanity

• Sedative and transquillizing agent (Reserpine group)

• Ajmaline - pharmacological properties similar to quinidine – cardiac arrhythmias

• Yohimbine – treatment of impotence

Substitutes

• R. vomitoria – African rauwolfia – bushy plant/tree, contains bands of sclereids and large vessels

• R. densiflora – absence of stratified cork, sclerenchyma (cortex and phloem)

• R.tetraphylla – Uniform cork (non-stratified), abundant sclereids, absence of recinnamine

Summary

• Dried roots of Rauwolfia serpentina with bark intact, contains not less than 0.15 % of reserpine group of alkaloids, calculated as reserpine Indole alkaloids – Reserpine – antihypertensive, sedative