Two New Cytotoxic Candidaspongiolides from an Indonesian Sponge

Marine sponges have been recognized as potentially rich sources of various bioactive molecules. In our continuing search for new secondary metabolites from Indonesian marine invertebrates, we collected a sponge, whose extract showed cytotoxicity against cultured cells at 0.1 μg/mL. Purification of the extract yielded two new macrolides 2 and 3 along with known candidaspongiolide (1). The structures for compounds 2 and 3 were elucidated by spectral analysis ((1)H, (13)C, COSY, HMQC, HMBC) and by comparison of their NMR data with those of 1. Compounds 2 and 3 exhibited a little more potent cytotoxicity (IC(50) 4.7 and 19 ng/mL) than that (IC(50) 37 ng/mL) of candidaspongiolide (1) against NBT-T2 cells.