OSMAC strategy integrated with molecular networking discovery peniciacetals A−I, nine new meroterpenoids from the mangrove-derived fungus Penicillium sp. HLLG-122

Nine new highly oxygenated meroterpenoids, peniciacetals A−I (1–9), along with five known analogues (10–14) were isolated from the mangrove-derived fungus Penicillium sp. HLLG-122 based on the guidance of molecular networking and OSMAC approach. Peniciacetals A−B (1–2) were characterized with a unique 6/6/6/6/5 pentacyclic system possessing an unusual 4,6-dimethyl-2,5-dioxohexahydro-6-carboxy-4H-furo[2,3-b]pyran moiety. Peniciacetals C−D (3–4) possessed an uncommon 3,6-dimethyldihydro-4H-furo[2,3-b]pyran-2,5-dione unit with 6/6/6/5/6 fused pentacyclic skeleton. The structures and absolute configurations of new compounds were elucidated by HR-ESI-MS, 1D and 2D NMR spectroscopic data, X-ray diffraction analysis, and quantum chemical electronic circular dichroism (ECD) calculation. The plausible biosynthetic pathway of 1–9 were also proposed. Compound 14 showed good cytotoxicity against HepG2, MCF-7, HL-60, A549, HCT116 and H929 cell with IC50 values of 6.6, 14.8, 3.2, 5.7, 6.9 and 3.0 μM, respectively. Further research showed that the compound 14 induced necrosis or late apoptosis contributes to the HL-60 cells toxicity.