Two new sesterterpenoids and a new 9,11-secosterol from Spongia matamata.

Two novel sesterterpenoids, 12 alpha-acetoxy-19 beta-hydroxyscalara-15,17- dien-20,19-olide (3) and 12 alpha,-16 beta-diacetoxyscalarolbutenolide (5), and a new 9,11-secosterol, 3 beta-hydroxy-5 alpha,6 alpha-epoxy-9-oxo-9,11-seco-5 alpha-cholest-7-en-11-al (6), were isolated from the marine sponge Spongia matamata from Palau together with the known compounds scalarin (1) and 12 alpha-acetoxy-16 beta-hydroxyscalarolbutenolide (4). The structures were determined by interpretation of spectroscopic data.