Chloctanspirones A and B, novel chlorinated polyketides with an unprecedented skeleton, from marine sediment derived fungus Penicillium terrestre

Two novel chlorinated sorbicillinoids named chloctanspirones A (1) and B (2), possessing an unprecedented bicyclo[2.2.2]octane-2-spiro cyclohexane skeleton, together with their quasi-precursors terrestrols K (3) and L (4), two additional new chlorinated compounds, were isolated from a marine sediment derived fungus Penicillium terrestre. Their structures including absolute stereochemistries were elucidated by analysis of NMR, MS data, and TDDFT CD calculations. The cytotoxic effects of 1–4 were preliminarily evaluated in HL-60 and A-549 cells. Compound 1 was active against both HL-60 and A-549 cells with IC50s 9.2 and 39.7 μM, respectively, while 2 showed weaker activity only against HL-60 cells (IC50 37.8 μM).