Azaphilones and p-Terphenyls from the Mangrove Endophytic Fungus Penicillium chermesinum (ZH4-E2) Isolated from the South China Sea

Eight secondary metabolites, including three new azaphilones (chermesinones A–C, 1–3), three new p-terphenyls (6′-O-desmethylterphenyllin, 4; 3-hydroxy-6′-O-desmethylterphenyllin, 5; 3′′-deoxy-6′-O-desmethylcandidusin B, 7), and two known p-terphenyls (6, 8), were isolated from the culture of the mangrove endophytic fungus Penicillium chermesinum (ZH4-E2). Their structures were established by spectroscopic analysis. The absolute configuration of 1 was determined by X-ray crystallography. Terphenyls 4, 5, and 6 exhibited strong inhibitory effects against α-glucosidase with IC50 values of 0.9, 4.9, and 2.5 μM, respectively. Terphenyls 7 and 8 showed inhibitory activity toward acetylcholinesterase with IC50 values of 7.8 and 5.2 μM.