Penicamins A–L, Polyoxygenated Diterpenes from <i>Penicillium camemberti</i> JSB-7212

Penicamins A-L (<b>1</b>-<b>12</b>), 12 highly oxygenated novel diterpenes, were obtained from the fungus <i>Penicillium camemberti</i> JSB-7212. Compounds <b>1</b>-<b>12</b> 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 <b>1</b>, <b>2</b>, and <b>4</b>-<b>12</b> were established by single-crystal X-ray diffraction, and the absolute configuration of <b>3</b> was determined by analysis of the NOESY data and biogenetic consideration. Compounds <b>2</b> and <b>3</b> 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.