The structure of Genin G(12-O-benzoyl-desacetylmetaplexigenin) and H (di-O-benzoyl-viminolon) from the stems of Sarcostemma viminale (L.) R. Br

The following structures for the two new genins G and H from Sarcostemma viminale have been deduced. Genin G is shown to be 12-O-benzoyl-deacetylmetaplcxigenin ( 3 ). On the basis of physical data, its behaviour in KOH-methanol solution and its positive test with alcaline silver-diammine solution, the structure of 3β, 8β, 14β, 17β-tetrahydroxy-12β, 21-dibenzoyloxy-20-oxo-17α-pregn-5-ene ( 4 ) is proposed for genin H. This substance therefore contains a dihydroxyacetone group like some corticoids (e.g. Cortisol), but with different stereochemistry at C-14 and C-17.