Dendronephthols A-C, new sesquiterpenoids from the Red Sea soft coral Dendronephthya sp.

Three new ylangene-type sesquiterpenoids: dendronephthol A (7,13-dihydroxy-3,4-dihydro-alpha-ylang-5-one) (1), dendronephthol B (6,7,13-trihydroxy-3,4-dihydro-alpha-ylangene) (2), and dendronephthol C (6,7,13-trihydroxy-alpha-ylang-5-one) (3), together with two known compounds: dendronesterone A and cholesterol were isolated from the CHCl3 fraction of Red Sea soft coral Dendronephthya sp. (Nephtheidae). The structures of the new compounds were established on the basis of one- and two-dimensional NMR spectroscopic studies (H-1, C-13, DEPT, COSY, HSQC, HMBC, and NOESY) as well as MS spectroscopy and by comparison of the spectral data with those of related known compounds. Compounds 1 and 3 showed cytotoxic activity against the murine lymphoma L5187Y cancer cell line with ED50 values of 8.4 and 6.8 mu g/mL, respectively. (C) 2014 Elsevier Ltd. All rights reserved.