Isochromophilones A–F, Cytotoxic Chloroazaphilones\nfrom the Marine Mangrove Endophytic\nFungus <i>Diaporthe</i> sp. SCSIO 41011

Six new highly oxygenated chloroazaphilone\nderivatives, isochromophilones\nA–F (<b>1</b>–<b>6</b>), were obtained from\nthe mangrove-derived fungus <i>Diaporthe</i> sp. SCSIO 41011,\ntogether with six known analogues (<b>7</b>–<b>12</b>). The structures of <b>1</b>–<b>6</b> including\nabsolute configurations were determined by detailed NMR, MS spectroscopic\nanalyses, and electronic circular dichroism spectra. Compounds <b>1</b> and <b>2</b> represent the first reported azaphilones\nlacking a carbonyl group at C-6. Compound <b>8</b> exhibited\ncytotoxic activities against three renal carcinoma cell lines, ACHN,\nOS-RC-2, and 786-O cells, with IC₅₀ values ranging from\n3.0 to 4.4 μM, and <b>4</b> showed activity against 786-O\ncells with an IC₅₀ of 8.9 μM. Further studies indicated\nthat <b>4</b> induced apoptosis in 786-O cells in a dose- and\ntime-dependent manner.