Phyllolactones A-E: new bishomoscalarane sesterterpenes from the marine sponge Phyllospongia lamellosa

Five new bishomoscalarane sesterterpenes, phyllolactones A-E (1-5), have be en isolated from the marine sponge Phyllospongia lamellosa. The structures were elucidated by 1D and 2D H-1 and C-13 NMR, unambiguous assignments of o verlapping H-1 and C-13 resonances were made by analysis of an HSQC-TOCSY s pectrum, and relative stereochemistry established by analysis of coupling c onstants and ROESY and NOESY spectra. A summary of previously reported carb olactone-containing bishomoscalarane structures and the range of C-13 chemi cal shifts arising from the various oxy substituents at C-3, C-12, C-16, C- 20 and C-24 is included. Phyllolactones A-E modestly inhibit HIV-1 envelope -mediated fusion in vitro with IC(50)s of similar to2 muM, and show negligi ble cytotoxicity toward the cell lines used in the fusion assay (BS-C-1 and NIH 3T3). Published by Elsevier Science Ltd.