Pregnane glycosides from Caralluma retrospiciens

Two pregnane ester glycosides were isolated and identified from the alcohol extract of the aerial parts of Caralluma retrospiciens. Their structures were established as 12 beta-benzoyloxy-20-isovaleroyloxy-8 beta,14 beta-dihydroxypregnane-3-O-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-(1-->4)-beta-D-(3-O-methyl-6-deoxy)galactopyranoside] (caretroside A) and the bioside 12 beta-benzoyloxy-8 beta,14 beta-dihydroxypregn-20-one-3-O-[beta-D-oleandropyranosyl-(1-->4)-beta-D-cymaropyranoside]. They were characterized through physical and chemical methods in addition to standard spectroscopic techniques especially 2D NMR (COSY, HMQC and HMBC). This is the first report of the isolation of these compounds from a natural source.