New triterpenoid saponins from the sponge Erylus nobilis

Erylosides G-J (1-4), four new triterpenoid saponins, were isolated from th e sponge Erylus nobilis collected from Jaeju Island, Korea. On the basis of the results of combined chemical and spectral analyses, the structures of the aglycones were determined to be lanostane-based, modified penasterols. The oligosaccharide portions were composed of one unit each of L-arabinose, D-galactose, and 2-N-acetyl-D-glucosamine (1 and 3) or two units of L-arab inose and one unit of 2-N-acetyl-D-glucosamine (2 and 4). These compounds e xhibited moderate cytotoxicty against a human leukemia cell line.