Biosynthesis, characterization and biological evalutation of Fe(III) and Cu(II) complexes of neoaspergillic acid, a hydroxamate siderophore produced by co-cultures of two marine-derived mangrove epiphytic fungi

Abstract

A hydroxamate siderophore, neoaspergillic acid (1), and a red pigment, ferrineoaspergillin (2) which is an Fe(III) complex of 1, were produced by co-cultures of two epiphytic fungi from a rotten fruit of the mangrove Avicennia marina from the South China Sea, and a new Cu(II) complex of 1, designated as cuprineoaspergillin (3), was also prepared by treatment of 1 with cupric acetate. All the compounds (1-3) were characterized by physical and chemical techniques, including 1H NMR, ESIMS, and photoelectron energy spectra. In the bioassays, compounds 1-3 showed significant inhibitory activities against selected Gram-positive and Gram-negative bacteria, and compound 1 also exhibited moderate inhibitory activities against human cancer cell lines SPC-A-1, BEL-7402, SGC-7901 and K562.