||In order to search for bioactive compounds, we have studied the chemical constituents from the organic extracts of soft coral Klyxum molle. In this study, fifteen eunicellin-type diterpenoids, including eleven new compounds, klymollins K–U (1–11), along with four known compounds 12–15 were isolated. Compounds 16 and 17 were prepared by chemical synthesis. The structures of all compounds were established by spectroscopic methods and comparing the spectral data with known compounds. Compound 5 represents the first eunicellin-type compound with phenylacetyl group.|
The cytotoxicity of compounds 1–17 against K562 (human erythro myeloblastoid leukemia), Molt-4 (human acute lymphoblastic leukemia), and T47D (human breast earcinoma) were determined. Compounds 1, 2, and 3 exhibited weak cytotoxicity against Molt-4 (with ED50 11.52 ± 2.75, 20.41 ± 2.92, and 13.11 ± 3.87 μg/mL). Compound 5 was found to exhibt significant cytotoxicity toward K562, Molt-4, and T47D (with ED50 4.32 ± 1.38, 2.36 ± 0.34, and 4.65 ± 0.93 μg/mL). Compound 5 also displayed significant inhibitory effects on superoxide anion generation and elastase release by human neutrophils at 10 μg/mL (with Inh % 81.56 ± 3.23, and 89.16 ± 5.77).