Paraminabeolides A-F, cytotoxic and anti-inflammatory marine withanolides from the soft coral Paraminabea acronocephala

Six new withanolides, paraminabeolides A-F (1-6), along with five known compounds, minabeolides-1, -2, -4, -5, and -8 (7-11), were isolated from a Formosan soft coral, Paraminabea acronocephala. The structures of these compounds were elucidated by extensive spectroscopic analysis and chemical transformation. The absolute configuration of 4 was determined by the application of Mosher's method. Compounds 1 and 7 were cytotoxic toward Hep G2 Cancer cells. Compounds 1-4 and 7-10 were found to significantly inhibit the accumulation of the pro-inflammatory iNOS protein. Compounds 7-10 also could effectively reduce the expression of COX-2 protein.