Steroidal Carboxylic Acids from Soft Coral Paraminabea acronocephala

Three new steroidal carboxylic acids, paraminabic acids A-C (1-3) were isolated from a Formosan soft coral Paraminabea acronocephala. The structures of these compounds were established by extensive spectroscopic analysis and chemical methods. Application of the PGME method allowed the establishment of the absolute configurations at C-25 and C-24 for 1 and 2, respectively. Compound 3 showed potent cytotoxicity toward Hep3B, MDA-MB-231, MCF-7, and A-549 cancer cell lines, with IC50 values ranging from 2.05 to 2.83 mu g/mL. Compounds 2 and 3 were found to inhibit the accumulation of the pro-inflammatory iNOS protein.