Puupehenone congeners from an indo-pacific Hyrtios sponge

An investigation of the constituents from an Indonesian Hyrtios sponge has provided new insights about the chemistry and biology of the puupehenones, a unique class of merosesquiterpenes. The parent compound, puupehenone (2), has been repeatedly encountered in sponges from four distinct orders. In this study we characterized three compounds, (+)-(5S,8S,9R,10S)-20-methoxypuupehenone (3), (+)(5S,8S,10S)-20-methoxy-9,15-ene-puupehenol (4), and (+)-(5S,8S,9R,10S)-15,20-dimethoxypuupehenol (5). Their structures were supported by complete sets of spectroscopic data along with comparisons to literature properties. While 5 was observed in the crude extracts, it was also heat labile and could be converted at 35 degreesC to a mixture of 3 and 4. The possibility that 3, 4, and 5 are formed from 2 by a series of methanol additions is discussed. The bioactivity of these compounds in soft-agar cytotoxicity tests was also explored.