Tanzawaic Acids from a Deep-Sea Derived Penicillium Species

Twelve new tanzawaic acid derivatives, penitanzacids A−F (1–6), and G−J (9–12), and hatsusamides C−D (13–14), together with two revised structures [tanzawaic acids I−J (7–8)] and three known compounds (15–17) were isolated from the deep-sea-derived fungus Penicillium sp. KWF32. Their structures including absolute configurations were elucidated by spectroscopic data analysis, HRESIMS data, modified Mosher’s method, chemical degradation studies, ECD calculations, single crystal X-ray diffraction, and biogenic considerations in comparison with reported known analogues. Penitanzacids H–J (10–12) represent the first examples of this family with a C3 side chain and support the proposed biosynthetic pathway in which the side chain is connected to the decalin backbone. Hatsusamides C–D (13–14) have a hybrid skeleton formed by linking a tanzawaic acid and a diketopiperazine through an ester bond. Compounds 13 and 14 exhibit weak cytotoxicity against the A549 cell line.