New polyoxygenated steroids exhibiting reversal of multidrug resistance from the gorgonian Isis hippuris

Eleven new () and one known () polyoxygenated steroids have been isolated from two collections of the gorgonian Isis hippuris and their structures determined by spectroscopic analysis and X-ray diffraction study. Except for all others were polyoxygenated gorgosterols. X-Ray study of the previously reported compound demonstrated the stereochemistry of the side chain moiety to be identical with that of gorgosterol. Compound was a deacetyl derivative of the known steroid having a spiroketal and a lactone function. The stereochemistry of was confirmed by X-ray analysis, which also established the C-22 configuration of which had remained unsolved. These compounds have been tested for reversal of multidrug resistance (MDR) with cancer cells expressing P-glycoprotein (P-gp). Some of them showed moderate activity.