Trichodermamides D–F, heterocyclic dipeptides with a highly functionalized 1,2-oxazadecaline core isolated from the endophytic fungus Penicillium janthinellum HDN13-309†
Three new heterocyclic dipeptides with a highly functionalized 1,2-oxazadecaline core, named trichodermamides D–F (1–3), together with the known trichodermamides A–C (4–6), were isolated from the broth of the mangrove-derived endophytic fungus Penicillium janthinellum HDN13-309. The structures were elucidated through extensive NMR spectroscopic and physical data. The absolute configurations of compounds 1–3 were determined by ECD calculations and single-crystal X-ray diffraction experiments. The cytoprotective activities were evaluated on different phase II detoxifying enzymes (SOD2, AKR1C1, HO-1 and NQO1), and compounds 4 and 6 showed potent inducing effects at the concentration of 10 μM.