Identification and bioactivity evaluation of secondary metabolites from Antarctic-derived Penicillium chrysogenum...

Extracts from Antarctic-derived Penicillium chrysogenum CCTCC M 2020019 showed potent antibacterial bioactivities. We report herein the isolation of chrysonin (1), a new compound containing a pair of enantiomers 6S- and 6R-chrysonin (1a and 1b) featuring an unprecedented eight-membered heterocycle fused with a benzene ring. Compound 2, a mixture consisting of a new zwitterionic compound chrysomamide (2a) and N-[2-trans-(4-hydroxyphenyl) ethenyl] formamide (2b) in a ratio around 1 : 2.8, was isolated together with seven known compounds 3-9. Chemical structures of all compounds were determined by comprehensive spectroscopic analyses. The isolated compounds were evaluated for antimicrobial, cytotoxic and alpha-glucosidase inhibition activities. Chrysonin (1) showed moderate alpha-glucosidase inhibitory activity. The dominant product xanthocillin X (4) displayed potent inhibition activities against Gram-negative pathogens Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa with MIC values at 0.125 μg mL^-1. Xanthocillins X (4) and Y1 (5) also showed significant cytotoxicities against four cancer cell lines with IC₅₀ values ranging from 0.26 to 5.04 μM. This study highlights that microorganisms from polar regions are emerging as a new resource for the discovery of natural products combating human pathogens.