Klysimplexins I–T, eunicellin-based diterpenoids from the cultured soft coral Klyxum simplex

New eunicellin-base diterpenoids, klysimplexins I–T (1–12), were isolated from a cultured soft coral Klyxum simplex. Their structures were elucidated by spectroscopic methods, particularly in 1D and 2D NMR experiments. The absolute stereochemistry of 4 was determined by Mosher's method. Compounds 9 and 12 have been shown to exhibit cytotoxicity toward a limited panel of cancer cell lines. Compounds 2–6, 10 and 11 were found to display significant in vitro anti-inflammatory activity in LPS-stimulated RAW264.7 macrophage cells by inhibiting the expression of the iNOS protein. Compounds 10 and 11 also could effectively reduce the level of COX-2 protein.