Antagonistic Activity of Oroxylin A against Fusarium graminearum and Its Inhibitory Effect on Zearalenone Production.

Fusarium graminearum produces zearalenone (ZEA), a mycotoxin that is widely found in food and feed products and is toxic to humans and livestock. Piper sarmentosum extract (PSE) inhibits F. graminearum , and Oroxylin A appears to be a major antifungal compound in PSE. The aim of this study is to quantify the Oroxylin A content in PSE using UPLC-QTOF-MS/MS, and to investigate the antagonistic activity of Oroxylin A against F. graminearum and its inhibitory effect on ZEA production. The results indicate that Oroxylin A inhibits both fungal growth and ZEA production in a dose-dependent manner. Oroxylin A treatment downregulated the mRNA expression of zearalenone biosynthesis protein 1 ( ZEB1 ) and zearalenone biosynthesis protein 2 ( ZEB2 ). The metabolomics analysis of F. graminearum mycelia indicated that the level of ribose 5-phosphate (R5P) deceased ( p < 0.05) after Oroxylin A treatment (64-128 ng/mL). Moreover, as the Oroxylin A treatment content increased from 64 to 128 ng/mL, the levels of cis -aconitate ( p < 0.05) and fumarate ( p < 0.01) were upregulated successively. A correlation analysis further showed that the decreased R5P level was positively correlated with ZEB1 and ZEB2 expression, while the increased cis -aconitate and fumarate levels were negatively correlated with ZEB1 and ZEB2 expression. These findings demonstrate the potential of Oroxylin A as a natural agent to control toxigenic fungi and their mycotoxin.