Study on the secondary metabolites and biological activities of the endophytic fungus Septoriella phragmitis in Huaze Lan

There are abundant species of endophytic fungi in plants, and their metabolites are diverse, which may produce various active substances similar to those of the host. Modern pharmacological studies have shown that the extract of the endophytic fungus Septoriella phragmitis from Huaze orchid has activities such as antidepressant, anti-inflammatory, immune regulation, and antioxidant. Zhang et al. isolated 8 endophytic fungi from Hua Zelan and conducted in vitro anti-tumor experiments on the ethyl acetate extract of their fermentation broth, but lacked research on individual compounds. The research team isolated an endophytic fungus from the roots of Huaze Lan, and after strain identification, it was determined that it is different from the endophytic fungus isolated by Zhang Jianfen et al., and is Septoriella phragmitis. There is currently no literature reporting information on its secondary metabolites. In order to further study the material basis of the endophytic fungus Septoriella phragmatis, this study isolated and identified its chemical components, and tested its anti diabetes and anti-tumor activities, providing a reference for finding a highly effective and low toxic anti diabetes lead compound and developing and utilizing this medicinal fungus resource.

This study explored the chemical composition of the strain and obtained 10 compounds, including 5 alkaloids, 4 phenols, and 1 benzofuran, all of which were isolated from the strain for the first time. Additionally, it was discovered for the first time that microorganisms can produce the active ingredient of the plant Eupatorium adenophorum – puerarin. The pharmacological activity test results showed that compounds 6 and 7 had good inhibitory activity against alpha glucosidase, respectively; Compounds 6, 7, and 9 exhibit good PTP1B inhibitory activity, and their activity is superior to that of the positive drug sodium orthovanadate; Compounds 5 and 6 exhibit certain inhibitory activity against gastric cancer cell line HGC-27 compared to other compounds. Further molecular docking experiments showed that compounds 6 and 7 can interact with amino acid residues of α – glucosidase or PTP1B target proteins through various interactions such as hydrogen bonding, hydrophobicity, conjugation, etc. At present, no literature has reported the secondary metabolites of the fungus Septoriella phragmatis. This study reported the secondary metabolites of this strain for the first time, and some of the compounds found have dual target inhibitory activity against diabetes.