Isolation and identification of polyketides from the endophytic fungus Diaporthe pseudomagiferae derived from Acanthus ilicifolius L. and studies on their anti-oxidant and anti-inflammatory activities in vitro

Objective: To investigate the isolation and purification of the polyketide compounds and their anti-oxidant and anti-inflammatory activities in the endophytic fungus Diaporthe pseudomagiferae from Acanthus ilicifolius L. Methods: The compounds were separated and purified by column chromatography on silica gel, Sephadex LH-20, and high-performance liquid chromatography, and the structures of compounds were analyzed by combining with comprehensive spectral techniques such as high resolution mass spectra (MS) and nuclear magnetic resonance (NMR) spectroscopy. The anti-inflammatory and anti-oxidant activities of some pure compounds were evaluated. Results: A total of seven polyketides were isolated from rice fermentation products of Diaporthe pseudomagiferae and identified as (8-Methyl-9-oxabicyclo 4.2.1 nona-2,4-dien-7-yl) -(5-oxo-2H-furan-2-yl) methyl acetate (1), 2,3-Dihydromycoepoxydiene (2), Dothiorelone A (3), Dothiorelone B (4), Cytosporone B (5), 5,6-dihydroxy-2,3,6-trimethylcyclohex-2-enone (6), 3-(4-Methylphenoxy) propanoic acid (7). The free radical scavenging experiment of 1, 1-diphenyl-2-trinitrophenylhydrazine (DPPH) showed that compounds 1-5 did not exhibit anti-oxidant activity. The results of enzymed-linked immunosorbent assay (ELISA) showed that compounds 1-5 had inhibitory effects on interleukin-6 (IL-6) release from RAW264.7 cells induced by lipopolysaccharide (LPS). Conclusion: Compounds 1, 3, 4, and 6 have been isolated from the endophytic fungus Diaporthe pseudomagiferae from Acanthus ilicifolius L. for the first time. Compounds 1-5 exhibit certain anti-inflammatory activity, which lays the foundation for further exploring the anti-inflammatory mechanisms of relevant active substances