Regulation of secondary metabolites in the endophytic fungus sp. KMU18029 by the chemical epigenetic modifier 5-azacitidine.

The chemical epigenetic modifier 5-azacitidine (5-Aza C), a DNA methyltransferase inhibitor, was used to manipulate the endophytic fungus sp. KMU18029. From its rice fermentation extract, a new polyketone compound (3,4)-3,4,8-trihydroxy-6-methyl-3,4-dihydronaphthalen-1(2)-one (), along with 13 known compounds, 3,4,8-trihydroxy-6-(hydroxymethyl)-3,4-dihydronaphthalen-1(2)-one (), decaturin B (), 15-hydroxydecaturin A (), oxalicine A (), pileotin A (), pyrandecarurin A (), decaturenol A (), decaturenoid (), penisarins A (), oxaline (), (4,8)-N-D-2'-hydroxyocta-decanoyl-1-O--D-glycopy-ranosyl-9-methyl-4,8-sphingadienine (), ergosterol () and stigma-5-en-3-O--glucoside (), were separated. Among the known compounds, , , and were not found in our previous research on this strain. The structure of the new compound was identified by spectroscopic techniques such as HR-ESIMS, 1D NMR, 2D NMR and CD. Furthermore, all the isolated compounds were tested for their antimicrobial activities, and only compounds , and showed weak activities against , with MICs of 128 μg/mL.