Biotransformation of digitoxigenin by cultured Strophanthus hybrid cells

Hybrid cells between Strophanthus gratus and S. amboensis were obtained by electrofusion and confirmed to be hybrids through isozyme and RFLP analyses. Because a new and hybrid compound, 17 beta H-periplogenin beta-D-glucoside, was isolated as a biotransformation product of digitoxigenin by the hybrid cells, isomerization of 17 beta-lactone ring on S. gratus and glucosylation on S. amboensis were demonstrated simultaneously as the biotransformation abilities in the hybrid cells. Moreover, the productivity of the hybrid compound was increased by raising the sucrose concentration.