Diversity of Endophytic Fungi Isolated From Huperzia serrata and Research on the Secondary Metabolites of Penicillium panissanguineum SZSS 4-2-2.

A total of 46 endophytic fungi were isolated from Huperzia serrata and then cultured in a standard liquid medium and PDB medium. Cytotoxicity and antimicrobial activity assays revealed that seven crude extracts exhibited significant inhibitory effects on MCF-7 and SH-SY5Y cell lines; four crude extracts effectively inhibited the growth of Candida albicans, and 12 crude extracts demonstrated potent inhibition effects on Staphylococcus aureus. Strains displaying antimicrobial activity or potential for producing novel metabolites were selected for identification. In total, 14 strains representing 7 genera were identified, 5 of which had not been previously documented regarding their secondary metabolites. A fungus, Penicillium panissanguineum SZSS 4-2-2 was preliminarily selected for further chemical investigation. From the fermentation extract of P. panissanguineum SZSS 4-2-2, one new compound (1), one new natural product (2), and two known compounds (3 and 4) were isolated. The structures of these compounds were elucidated through spectral analysis and calculated nuclear magnetic resonance and electronic circular dichroism data. Compound 1 demonstrated a significantly stronger inhibitory effect on lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 macrophages, with an IC50 value of 64.91 µM. By contrast, compounds 2, 3, and 4 exhibited only moderate inhibitory effects on NO production.