Improvement of Diosgenin Yield from Dioscorea deltoidea Plant Cell Cultures by Use of a Non-Traditional Hydrolysis Method

Abstract

The attractiveness of fermentor cultures of Dioscorea deltoidea Wall. (Dioscoreaceae) as a source of diosgenin has been greatly improved by switching away from the traditional product recovery method that has been used in all previous studies. By using a known but little-used hydrolysis method involving 2N H₂SO₄ in 70% isopropanol rather than using 2N aqueous HCl, diosgenin was found to be a growth-associated product instead of a non-growth-associated product as was formerly thought. This is an important improvement from a biotechnological standpoint because it means that diosgenin can be obtained directly from growth-phase tissue and that a non-growth phase is unnecessary. The reason that switching hydrolysis methods has this impact is that the non-traditional method gives high diosgenin yields from a broader group of steroidal glycosides. During the non-growth phase, steroidal glycosides were found to spontaneously change from furostanol saponins to spirostanol saponins. Whereas the nontraditional hydrolysis method gives high diosgenin yields from both types, the traditional method gives high yields only from the latter type.