Synonym: Yam

Biological source:

Dioscorea consist of tubers or rhizomes of a number of cultivated and wild species of genus Dioscorea such as Dioscorea deltoidea wall, D. composite, D. floribunda

Family: Dioscoreaceae

Macroscopical characters:

• Colour: Slightly brown

• Odour: Odourless

• Taste: Bitter

• Shape:

  • • • • It is a climber with alternate leaves

        • Rhizomes are soft, horizontally arranged and are very close to the soil.

        • Drug is covered with scattered roots. They weigh about 20-50 g.

Uses

Pharmaceutically, the rhizomes are used as rich source of diosgenin.

Diosgenin being steroidal in nature is used as precursor for synthesis of several corticosteroids, sex-hormones, and oralcontraceptives.

Dioscorea is used in the treatment of rheumatic arthritis.

After isolation, diosgenin is degraded to 16-dehydro pregnenelone acetate is used as precursor for synthesis of Corticosteroids like cortisone, hydrocortisone, prednisolone,

Pregnenes Iike progesterone, 17 -α- hydroxy progesterone,

Androstanes like testosterone, methyl testosterone, etc.

19 - NOR steroids like estrone, 17 – α- ethynyl estradiol and norethisterone acetate.

The conversions are done with the help of microbial transformations

Isolation

• The tubers are dried, powdered and hydrolysis of dioscin is done by mineral acids.

• The liberated diosgenin is extracted with the help of non-polar solvents like benzene or solvent ether.

• After isolation, diosgenin is degraded to 16-dehydro pregnenelone acetate.

Allied Species:

• Dioscorea villasa

• Costus speciosus is an alternative potential source for diosgenin

References:

1. Trease D. & Evans W.C.: Text Book of Pharmacognosy: W.B. Saunders.

2. Tyler V. E. Brady L. R. & Robbers J. E.: Pharmacognosy; Lea Feibger, USA.

3. Wallis T. E.; Text Book of Pharmacognosy; CBS Publishers, Delhi.

4. Kokate C. K., Purohit A. P. & Gokhale S. B.: Pharmacognosy; Nirali Publications, Pune.

5. Harbone J. B.: Phytochemical Methods: A guide to modern techniques Analysis: Chapman & Hall, London.

6. Bruneton J.: Pharmacognosy, Phytochemistry, Medicinal Plants: Intercept Limited.