Dioxomorpholines and Derivatives from a Marine-Facultative <i>Aspergillus</i> Species

Two new dioxomorpholines, <b>1</b> and <b>2</b>, three new derivatives, <b>3</b>–<b>5</b>, and the known compound PF1233 B (<b>6</b>) were isolated from a marine-facultative <i>Aspergillus</i> sp. MEXU 27854. Their structures were established by 1D and 2D NMR and HRESIMS data analysis. The absolute configuration of <b>1</b> and <b>2</b> was elucidated by comparison of experimental and DFT-calculated vibrational circular dichroism spectra. Compounds <b>3</b>, <b>5</b>, and <b>6</b> 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