Lembehsterols A and B, novel sulfated sterols inhibiting thymidine phosphorylase, from the marine sponge Petrosia strongylata.

Lembehsterols A (1) and B (2), two novel sulfated sterols, were isolated from the marine sponge Petrosia strongylata. Both sterols showed inhibitory activity against thymidine phosphorylase, which is an enzyme related to angiogenesis in solid tumors. The structures of these sulfated sterols were established on the basis of chemical and physicochemical evidence.