Aurisides A and B, Cytotoxic Macrolide Glycosides from the Japanese Sea Hare Dolabella auricularia

Bioassay-guided fractionation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia led to the isolation of two novel cytotoxic compounds, aurisides A (1) and B (2). Their gross structures were established by spectroscopic analysis including the 2D NMR technique. On the basis of the NOESY spectral analysis and the degradation experiments, their absolute stereostructures were determined to be 14-membered macrolide glycosides that contain a bromine-substituted conjugated diene structure, a cyclic hemiacetal moiety, and a 2,4-di-O-methyl-L-rhamnopyranoside part. Aurisides A (1) and B (2) show cytotoxicity against HeLa S(3) cells with IC(50) values of 0.17 and 1.2 g/mL, respectively.