Chemistry Letters, Vol.30, No.2, 176-177, 2001
Kohamaic acids A and B, novel cytotoxic sesterterpenic acids, from the marine sponge Ircinia sp.
Two new sesterterpenic acids, which exhibited moderate cytotoxicity, were isolated from the marine sponge Ircinia sp. Their absolute stereochemistries were determined by spectroscopic and chemical analyses. Their configurations at C15 were different from those of previously isolated sesterterpenes. This result suggests the existence of a (14Z)-geranylfarnesyl pyrophosphate, which is yet unknown in nature.