Bioactive natural products of Aspergillus sp. OUCMDZ-1914, an aciduric fungus from the mangrove soils

Abstract

In order to investigate bioactive metabolites from aciduric fungi, Aspergillus sp. OUCMDZ-1914 was isolated from the mangrove soil in Wenchang Hainan, China. The strain was fermented under low pH and the products were extracted and the extract was purified by column chromatography over silica gel, Sephadex LH-20 and semi-preparative HPLC. The structures were identified by means of NMR, MS, UV, IR and X-ray single crystal diffraction. As a results, a new compound, methyl (2Z,3E,5E,7E,9E)-4,10-dimethyl-11-(2,5-dioxopyrrolidin-3-yl)-2-(2-hydroxyethylidene)-11-oxoundeca-3,5,7,9-tetraenoate (1), along with eight known ones, RKB-3384A (2), JBIR-74 (3), JBIR-75 (4), secalonic acid D (5), oxaline (6), meleagrin (7), okaramine H (8) and citreorosein (9), was obtained. Compound 2 showed H1N1 influenza virus inhibition with an IC50 value of 116.2 μmol/L. Compound 5 showed cytotoxicities against A549, MCF-7 and K562 cell lines with the IC50 values of 0.23, 4.45 and 3.68 μmol/L respectively. Compound 6 showed α-glucosidase inhibition with an IC50 value of 0.84 mmol/L.