Penicillium polonicum MCCC3A00951 is a fungus with influenza neuraminidase (NA) inhibition activity derived from a sediment of the mangrove forest of Zhangjiangkou in Fujian province, China. Chemical investigation on an ethyl acetate extract of its fermentation led to the isolation of a new compound, 7-hydroxy-3,10-dehydrocyclopeptine (1), and 13 known compounds (2-14). The new compound was comprehensively characterised by high-resolution electrospray ionisation-mass spectrometry, and 1D, 2D nuclear magnetic resonance (NMR) spectra. The anti-influenza NA assay was performed to evaluate the potential biological activity. Surprisingly, Cyclopenin (2) showed potent influenza NA inhibition with an IC50 value of 5.02 μM. Besides, molecular docking simulation was performed to investigate the binding model of cyclopenin (2) with influenza NA. Consequently, cyclopenin (2) could be further optimised to be a potential anti-influenza NA candidate.
Keywords: Anti-influenza neuraminidase activity; Penicillium polonicum MCCC3A00951; cyclopenin; mangrove fungus; molecular docking.