Abstract: 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 dosedependent
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 mycotoxi