Dioxomorpholines and Derivatives from a Marine-Facultative Aspergillus Species.

Two new dioxomorpholines, 1 and 2, three new derivatives, 3-5, and the known compound PF1233 B (6) were isolated from a marine-facultative Aspergillus sp. MEXU 27854. Their structures were established by 1D and 2D NMR and HRESIMS data analysis. The absolute configuration of 1 and 2 was elucidated by comparison of experimental and DFT-calculated vibrational circular dichroism spectra. Compounds 3, 5, and 6 were noncytotoxic to a panel of human cancer cell lines with different functional status for the tumor-suppressor protein p53, but were inhibitors of P-glycoprotein-reversing multidrug resistance in a doxorubicin-resistant cell line.