Antimicrobial polyketides from the endophytic fungus Fusarium asiaticum QA-6 derived from medicinal plant Artemisia argyi

Abstract

Seven previously undescribed polyketide derivatives, fusariumtides A–G (1–7), together with three known analogues (8–10), were isolated from the culture extract of Fusarium asiaticum QA-6, an endophytic fungus obtained from the fresh stem tissue of the medicinal plant Artemisia argyi H. Lev. & Vaniot. Their structures were elucidated by detailed interpretation of 1D/2D NMR spectroscopic and mass spectrometric data, and the absolute configuration of compound 1 was established on the basis of X-ray crystallographic analysis and ECD and specific rotation (SR) calculations. The isolated compounds, which possessed a functionalized decalin moiety, were evaluated for antimicrobial activities. Compounds 1 and 10 exhibited broad-spectrum inhibitory activities against nine tested pathogenic bacteria with MIC values ranging from 1 to 64 μg/mL, while compound 8 showed potent inhibitory activities against aquatic pathogens Aeromonas hydrophilia, Pseudomonas aeruginosa, Vibrio harveyi, and V. vulnificus, which were comparable to/or stronger than those of the positive control chloramphenicol.