Secondary Metabolites of a Mangrove Endophytic Fungus Aspergillus terreus (No. GX7-3B) from the South China Sea

Abstract

The mangrove endophytic fungus Aspergillus terreus (No. GX7-3B) was cultivated in potato dextrose liquid medium, and one rare thiophene compound (1), together with anhydrojavanicin (2), 8-O-methylbostrycoidin (3), 8-O-methyljavanicin (4), botryosphaerone D (5), 6-ethyl-5-hydroxy-3,7-dimethoxynaphthoquinone (6), 3β,5α-dihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (7), 3β,5α,14α-trihydroxy-(22E,24R)-ergosta-7, 22-dien-6-one (8), NGA0187 (9) and beauvericin (10), were isolated. Their structures were elucidated by analysis of spectroscopic data. This is the first report of a natural origin for compound 6. Moreover, compounds 3, 4, 5, 7, 8 and 10 were obtained from marine microorganism for the first time. In the bioactive assays in vitro, compounds 2, 3, 9 and 10 displayed remarkable inhibiting actions against α-acetylcholinesterase (AChE) with IC50 values 2.01, 6.71, 1.89, and 3.09 μM, respectively. Furthermore, in the cytotoxicity assays, compounds 7 and 10 exhibited strong or moderate cytotoxic activities against MCF-7, A549, Hela and KB cell lines with IC50 values 4.98 and 2.02 (MCF-7), 1.95 and 0.82 (A549), 0.68 and 1.14 (Hela), and 1.50 and 1.10 μM (KB), respectively; compound 8 had weak inhibitory activities against these tumor cell lines; compounds 1, 2, 3, 4, 5, 6 and 9 exhibited no inhibitory activities against them.

Keywords

• mangrove endophytic fungi
• thiophene
• secondary metabolites
• cytotoxicity
• AChE