Antifungal activity of flavonoids from Heteropterys byrsonimifolia and a commercial source against Aspergillus ochraceus: In silico interactions of these compounds with a protein kinase

To contribute to the development of new methods to reduce the contamination of coffee beans with Aspergillus ochraceus and ochratoxin A, a toxin produced by this fungus, the present work initially aimed to select plant extracts active against A. ochraceus. Among the extracts from 43 plant species, the most active was the one obtained from leaves of Heteropterys byrsonimifolia. This extract was subjected to a fractionation process that resulted in the purification of four flavonoids, among which the most active against the fungus was rutin, which presented a minimal inhibitory concentration (MIC, 32.5 μg/mL) close to the value obtained for the commercial fungicide benzalkonium chloride (7.84 μg/mL). In vitro studies with the isolated flavonoids and other four from commercial sources showed that the MIC for the flavonoid chrysin is equal to that observed for rutin, and results from an in silico study suggested that these flavonoids act against A. ochraceus by binding to a protein kinase produced by this fungus. Consequently, this enzyme and the studied flavonoids are potentially useful for the development of new products to control A. ochraceus in coffee beans. [Display omitted] •Extracts from 43 plants were screened for activity against Aspergillus ochraceus.•The most active extract was obtained from leaves of Heteropterys byrsonimifolia.•Rutin was the isolated flavonoid with smallest MIC value against the fungus.•Among the flavonoids from commercial source chrysin was the most active.•In silico study suggests the binding of these flavonoids to protein kinases.