Evaluation of diosgenin, a bioactive compound from natural source of Dioscorea species: A wild edible tuber plant

Dioscorea is a genus of over 600 species in the family Dioscoreace distributed throughout the tropical and warm temperate regions of the world. The members of the genus Dioscorea are one of the oldest tuber crop cultivated or harvested from wild in the tropical region throughout the world and constitute one of the major food item for many ethnic groups. India having rich plant biodiversity possesses about 50 species of Dioscorea and among them some have excellent medicinal and nutritional properties. Dioscorea, popularly known as Yam worldwide and as Ban Aalu in Odisha, India, is a prime staple medicinal-food substitute for the majority of rural and local people staying in forests of Eastern ghats of Odisha. There are about 13 type of Dioscorea species found in Eastern ghats of Odisha. Diosgenin, a commercially important bioactive sapogenin, extracted from tubers belonging to Dioscorea species, is used as a precursor in manufacturing of sex hormones, oral contraceptives and other pharmaceutically important steroidal drugs. With the view to commercially exploit a new source of diosgenin, lesser explored tubers of seven species of Dioscorea namely; D. bulbifera L.(2), D. pentaphylla L.(5), D. hispida Dennst.(1), D. alata L. (3), D. oppositifolia L. (2), D. pubera Blume (2), D.hamiltonii Hook. f.(1) were collected from Eastern Ghats of Odisha through explorations. The diosgenin content was determined in dried tuber by acidic hydrolysis of the glycosides and subsequent extraction with an organic solvent, followed by the HPTLC analysis. HPTLC mobile phase was optimized to toluene: ethyl acetate: formic acid (6: 5:1 v/v), and diosgenin content was found in the range of 0.001 to 0.003% on dry weight basis. The lower diosgenin content presently detected in the species may be due to the interaction of environmental factors or may be due to genetic makeup of the parent clones.