Diterpenes and sterols from the Red Sea soft coral and their cytotoxicity and anti-leishmanial activities.

The ethyl acetate and dichloromethane-soluble fractions, from a soft coral total methanolic extract, exhibited significant anti-leishmanial and cytotoxic activities. These active fractions yielded a new cembranoid diterpene (), two known analogues [sarcotrocheliol () and sarcophine ()], and two sterols [(24)-24-methylcholesterol () and gorgosterol ()]. The structure of the new diterpene () was determined via a detailed analysis of its spectroscopic data. Compounds and demonstrated noticeable cytotoxicity on A549 (IC 17.4 ± 1.9 µg/ml) and HepG2 (IC 17.7 ± 1.5 µg/ml) cell lines, respectively. None of the isolates showed detectable anti-leishmanial activity (IC >100 µg/ml).