Scalarane-type bishomosester terpenes from the sponge Phyllospongia foliascens.

Five new 20,24-bishomoscalarane sesterterpenes, phyllactones A [1], B [2], C [3], D [4], and E [5], are reported from the sponge Phyllospongia foliascens collected in the waters of the Nansha Islands in the South China Sea. Structural elucidation of these compounds is based on spectral data and chemical conversions. Phyllactones A and B show moderate cytotoxicity against KB cells (IC50 20 micrograms/ml).