Three New 9,11-Secosterols from the Formosan Soft Coral Sinularia leptoclados

Chemical investigations of the Formosan soft coral Sinularia leptoclados resulted in the characterization of three new 9,11-secosterols, designated as leptosterols A-C (1-3), and six known 9,11-secosterols 5-10. Additionally, a cyclized 9,11-secosterol enol-ether 4 was obtained by allowing 5 to stand in CDCl3 overnight during NMR experiments. The structures of 1-4 were elucidated through extensive spectroscopic analyses. The cytotoxicity against selected cancer cells and antiviral activity against human cytomegalovirus (HCMV) of 1-10 were evaluated in vitro.