Using a kinase screen to investigate the constituents of the sponge Stelletta clavosa obtained from diverse habitats Original Research Article

Fourteen collections of the marine sponge Stelletta clavosa have been obtained from diverse Indo-Pacific locations in order to conduct a comparison of their major constituents. The dichloromethane extract of one collection (no. 00369) exhibited activity in a c-Raf-1 kinase assay. Bioactivity-directed isolation resulted in the known porphyrin analogs pyropheophorbide a (2) and purpurin 18 methyl ester (3). Further spectroscopic screening of the various sponge extracts resulted in the isolation of four swinholide polyketides, a carotenoid, and three diketopiperazines. Pyropheophorbide a (2) exhibited the best IC50 among the porphyrin type compounds (IC50 <0.31 μg/mL). This prompted further screening of 2 against a panel of 85 kinases.