H-1 and C-13 NMR signal assignments of Paecilin A and B, two new chromone derivatives from mangrove endophytic fungus Paecilomyces sp (tree 1-7)

Abstract

Two new natural products, named paecilin A (1) and B (2), together with two known compounds secalonic acid D (3) and (11)-cytochalasa-6(12),13-diene-1,21-dione-16,18-dimethyl-7-hydroxy-10-phenyl-(7S*,13E,16S*,18S*) (4), were isolated from the mangrove endophytic fungus, Paecilomyces sp. (tree 1-7) from the South China Sea. 1D and 2D NMR experiments including COSY, HMQC, and HMBC were used for the determination of their structures. In our cytotoxicity assays, secalonic D (3) showed cytotoxicity toward KB cells with IC50 < 1 mu g ml(-1) and inhibiting human topoisomerase I with IC50 at 0.16 mu mol ml(-1).1, 2, and 4 showed no activity to KB cells. Copyright (C) 2007 John Wiley & Sons, Ltd.