Oxirapentyns B–D produced by a marine sediment-derived fungus Isaria felina (DC.) Fr

Three new oxirapentyns B–D and one previously reported oxirapentyn A were isolated from the marine-derived fungus Isaria felina. [Display omitted] ► Three new oxirapentyns were isolated from the marine-derived fungus Isaria felina. ► The absolute configuration of oxirapentyn B was established by a combination of NMR, X-ray and a Mosher's ester method. ► Antibiotic and cytotoxic properties of oxirapentyns were evaluated. Three new highly oxygenated chromene derivatives, oxirapentyns B–D (1–3) and one known oxirapentyn A (4) were isolated from the lipophilic extract of the marine-derived fungus Isaria felina KMM 4639. The structures of compounds 1–3 were determined based on spectroscopic methods. The absolute configuration of oxirapentyn B (1) as 2R, 4S, 5S, 6S, 7R, 8S, 9S was established by a combination of modified Mosher's method, X-ray analysis, and NOESY data. Oxirapentyn A (4) showed weak cytotoxicity against SK-Mel-5, SK-Mel-28 human malignant melanoma, and T-47D human breast cancer cell lines.