Accumulation of sterols and steroidal sapogenins in developing fenugreek pods: Possible biosynthesis in situ

The accumulation of sterols and steroidal sapogenins was investigated in the seeds and pericarps of fenugreek (Trigonella foenum-graecum L.) during the development and maturation of the pod. Flowers and young pods contained high levels of these substances which decreased during the development of pericarps and seeds. Steroidal sapogenins (mainly diosgenin, tigogenin and their C-25 epimers) then accumulated strongly in seeds while the increase of sterols was very slight. Cholesterol showed similar, but less dramatic changes. Several other sterols, including pollinastanol (14 alpha-methyl-9 beta,19-cyclo-5 alpha-cholestan-3 beta-ol), and dihydroxylated sapogenins also appeared during the development and maturation of seeds. Labelling experiments with [2-C-14]-acetate were carried out on excised maturing pods. Radioactivity was found in the four sterolic forms, mono- and dihydroxylated sapogenins from the seeds. Labelled diosgenin was isolated and purified to constant specific radioactivity. These results indicate that excised maturing pods of fenugreek can biosynthesize sterols and steroidal sapogenins.