A new steroidal saponin, aferoside A, has been isolated from the roots
of Costus afer. Its structure was established as 3-O-{[beta-D-apiofur
anosyl-(1 --> 2)]-[alpha-L-rhamnopyranosyl-(1 --> 4)]-beta-D-glucopyra
nosyl}-25(R)-spirost-5-en-3 beta-ol by chemical transformations and va
rious spectroscopic methods, mainly 2D NMR techniques (COSY, HMQC and
HMBC). Copyright (C) 1996 Elsevier Science Ltd