Induction of steroidal 11 alpha-hydroxylase activity in the filamentous fungus Rhizopus nigricans by tomatidine and Primula veris root extract

The inducement of commercially important steroid 11 alpha-hydroxylation in the filamentous fungus Rhizopus nigricans by several plant saponins and sap onin aglycones was tested. The alpha-tomatine derived aglycone tomatidine a nd a saponin rich Primula veris root extract were found to be effective ind ucers of progesterone 11 alpha-hydroxylation in this saprophytic fungus. Fu rthermore, the transformation of progesterone to 5 alpha-pregnane-3,6,20-tr ione was detected after pre-incubation with these plant constituents. Howev er, the progesterone 11 alpha-hydroxylase activity remained near the consti tutive level after treatment of R. nigricans with solanidine, oat-leaf extr act and its beta-glucosidase treated derivative, while the presence of beta -escin and especially alpha-tomatine lowered the transformation capability of mycelia. (C) 1999 Academic Press.