Isolation and biological activities of chemical constituents from Aspergillus niger

Fungi, a renewable natural product resource trove, have garnered increasing attention recently. Aspergillus niger (A. niger) Ma001, a subspecies isolated from the human gut, exhibited moderate in vitro inhibition of carbapenem-resistant Acinetobacter baumannii (CRAB). However, research on its active ingredients remains insufficient. Therefore, chemical investigations of A. niger Ma001 resulted in the isolation and identification of 19 natural products. Among these, two were identified as new compounds: a coumarin dimer with an unusual 3,8' carbon bridge, designated as 7,7'-di-O-demethyl-3,8'-bisiderin (1), and a 3-hydroxyanthranilic acid derivative (9). Their structures were elucidated through comprehensive analyses utilizing mass spectroscopy and nuclear magnetic resonance. Bio-evaluations indicated that some of these compounds exhibited antibacterial, anti-inflammatory, or anticancer activities.