Minor and trace sterols in marine invertebrates 47. A re-investigation of the 19-nor stanols isolated from the sponge Axinella polypoides.

The aim of this research was to establish the true composition of the 19-nor stanols isolated from the sponge Axinella polypoides and to determine accurate stereochemistry for each 19-nor stanol isolated. The following new 19-nor stanols were collected from this sponge: (i) (22E,24S)-24-methyl-19,27-bisnor-5 alpha-cholest-22-en-3 beta-ol, (ii) (22R,23R)-22,23-methylene-19-nor-5 alpha-cholestan-3 beta-ol, (iii) (24 xi)-24-propyl-19-nor-5 alpha-cholestan-3 beta-ol and (iv) (23R,24R)-23,24-dimethyl-19-nor-5 alpha-cholestan-3 beta-ol. The general structure and stereochemistry of all fifteen 19-nor stanols were established by analysis of the MS and H-NMR (300 MHz, CDCl3) data measured for each compound. The relative percentage of 19-nor stanols having delta 22 double bonds should be sufficient to suggest that this sponge could be a potential source of starting material for the partial synthesis of certain oral contraceptives, which also have a 19-nor steroid nucleus.