Diverse bioactive compounds from Sarcophtyton glaucom: structure elucidation and cytotoxic activity studies

Chemical investigation of the Red Sea soft coral Sarcophyton glaucom collected at the coasts of Hurghada, Egypt, led to the isolation of one new naturally occurring 4-oxo-1,1′-pentanoic acid anhydride (1), along with four diterpenes; sarcophinone (2a), 8-epi-sarcophinone (2b), (+)-7α,8β-dihydroxydeepoxysarcophine (3), sinumaximol G (4), (+)-sarcophine (5), sesquiterpene; prostantherol (6), sterol; 3β,24S-ergost-5-en-ol (7) and hexadecanoic acid. The structures of the obtained compounds were established using diverse spectroscopic techniques including 1D and 2D NMR and HRMS. Biologically, in vitro cytotoxic activities of diterpenes 2–5 and prostantherol (6) were studied against the liver cancer HEPG2 cell line in comparison with the soft coral extract and doxorubicin as reference (IC50: 4.28 μg/mL). Compounds 2–6 exhibited potent–moderate cytotoxicity of IC50 between 9.97 μg/mL [for sinumaximol G (4)] and 17.84 μg/mL [for (+)-7α,8β-dihydroxydeepoxysarcophine (3)], whereas that for soft coral extract was determined at 24.71 μg/mL.