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.