Biocatalysis of the anticancer sipholane triterpenoids.

The Red Sea sponge CALLYSPONGIA (= SIPHONOCHALINA) SIPHONELLA is a rich source of sipholane triterpenoids. Biocatalysis of the major sipholanes, sipholenol A ( 1) and sipholenone A ( 2), respectively, by MUCOR RAMANNIANUS ATCC 9628 and CUNNINGHAMELLA ELEGANS ATCC 7929 afforded four new metabolites 3 - 6 along with sipholenol G and 28-hydroxysipholenol A. Major sipholanes along with their biocatalytic products were investigated for their antiproliferative activity against the highly malignant +SA mouse mammary epithelial cell line. Sipholenone A ( 2) was the most active sipholane inhibiting +SA cell proliferation with an IC 50 value of 20 - 30 μM. Sipholenone A, also, showed cytotoxicity against MCF-7 at a dose of 0.9 μM and antiangiogenic activity in the CAM (chorio-allantoic membrane) assay. This is the first report on anticancer activity of these triterpenoids.