... -free (aglycone), diosgenin is used for the commercial synthesis of cortisone, pregnenolone, progesterone, and other steroid products.It ... Costus speciosus, Smilax menispermoidea, species of Paris, Trigonella, and Trillium, and many species of Dioscorea - D. althaeoides, colletti, ... zingiberensis. Diosgenin is the precursor for the semisynthesis of progesterone which in turn was used in early combined ...