[Bioactive isomalabaricane triterpenes isolated from marine sponge Rhabdastrella aff. distincta].

OBJECTIVE

To study the chemical constituents of the marine sponge Rhabdastrella aff. distincta.

METHOD

Compounds were obtained by normal phase silica gel, Sephadex LH-20, reverse phase chromatogrophy and methylation method. These structures were determined on the basis of IR, MS, NMR spectral analysis.

RESULT

Eight compounds were isolated from bioactive CH3Cl fraction and identified as geoditin A (1), geoditin B (2), stellettin A (5), stellettin B (4), stellettin C (3), stellettinE (7), rhabdastrellic acid A (8) and the methyl ester of stellettin E (6).

CONCLUSION

All these compounds were obtained from this species for the first time.