Regulation of secondary metabolites in the endophytic fungus Penicillium 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 Penicillium sp. KMU18029. From its rice fermentation extract, a new polyketone compound (3 S ,4 R )-3,4,8-trihydroxy-6-methyl-3,4-dihydronaphthalen-1(2 H )-one ( 1 ), along with 13 known compounds, 3,4,8-trihydroxy-6-(hydroxymethyl)-3,4-dihydronaphthalen-1(2 H )-one ( 2 ), decaturin B ( 3 ), 15-hydroxydecaturin A ( 4 ), oxalicine A ( 5 ), pileotin A ( 6 ), pyrandecarurin A ( 7 ), decaturenol A ( 8 ), decaturenoid ( 9 ), penisarins A ( 10 ), oxaline ( 11 ), (4 E ,8 E )-N-D-2'-hydroxyocta-decanoyl-1-O- β -D-glycopy-ranosyl-9-methyl-4,8-sphingadienine ( 12 ), ergosterol ( 13 ) and stigma-5-en-3-O- β -glucoside ( 14 ), were separated. Among the known compounds, 2 , 7 , 12 and 14 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 1 , 2 and 11 showed weak activities against S. aureus , with MICs of 128 μg/mL.