Penicamins A–L, Polyoxygenated Diterpenes from Penicillium camemberti JSB-7212

Penicamins A–L (1–12), 12 highly oxygenated novel diterpenes, were obtained from the fungus Penicillium camemberti JSB-7212. Compounds 1–12 share the same 7/6/5 tricyclic skeleton as valparane-type diterpenes but differ in the absolute configurations at C-7, C-11, and C-14, as well as in the oxidation levels at C-6 and C-8, which were determined through extensive spectroscopic data interpretation. Stereochemical assignments of compounds 1, 2, and 4–12 were established by single-crystal X-ray diffraction, and the absolute configuration of 3 was determined by analysis of the NOESY data and biogenetic consideration. Compounds 2 and 3 were immunosuppressive against lipopolysaccharide (LPS)-induced B cells, with IC50 values of 3.0 and 7.9 μM, respectively. They also moderately suppressed concanavalin A (ConA)-induced T cell proliferation, with IC50 values of 19 and 20 μM, respectively.