Novel marine natural products.: Part 5 -: Evariquinone, isoemericellin, and stromemycin from a sponge derived strain of the fungus Emericella variecolor

From a strain of the fungus Emericella variecolor derived from the marine sponge Haliclona valliculata, two new natural products, evariquinone and isoemericellin, were isolated after HPLC-UV, -MS, and -NMR studies of the extract and their structures were elucidated by mass spectrometry and NMR experiments. Evariquinone showed antiproliferative activity towards KB and NCI-H460 cells at a concentration of 3.16 mug/ml. Furthermore, the fungus was found to produce the known metabolites stromemycin, shamixanthone, and 7-hydroxyemodin. Chemical degradation, NMR decoupling experiments, and spin-system simulation provided evidence for the double bonds in stromemycin to be all E-configured. ROESY experiments established the monosaccharide moiety to be glucose. (C) 2003 Elsevier Science Ltd. All rights reserved.