Chemical characterization and antifungal activity of extracts from the edible fungus Laetiporus sulphureus against Fusarium oxysporum, the causative agent of vascular fusariosis in Moroccan date palm

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This study examined the valorization of the edible and medicinal mushroom Laetiporus sulphureus, collected from northeastern Morocco, by analyzing its chemical composition and evaluating the antioxidant and antifungal activities of its methanolic, acetonic, ethanolic, hydromethanolic, hydroacetonic, and hydroethanolic extracts. Total phenolic content (TPC) and total flavonoid content (TFC) were determined using the Folin–Ciocalteu and aluminum chloride methods, respectively, while chemical characterization was performed using two chromatographic analyses: Gas Chromatography-Mass Spectrometry (GC-MS) and High-Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC-MS). Concerning biological activities, the 2,2-diphenyl-1-picrylhydrazyl(DPPH) radical scavenging method was used to evaluate antioxidant capacity, while the microdilution method was employed to assess antifungal activity against Fusarium oxysporum f. sp. albedinis. The results revealed significant phenolic compound contents, with TPC ranging from 19.24 to 30.47mg of gallic acid equivalent GAE/g and TFC from 11.09 to 17.98 mg of catechin equivalent CE/g of dry crude extract. GC-MS analysis identified 106 biologically active compounds across all samples, primarily classified as sugars (41%), fatty acids (18%), and organic acids (7%). HPLC-MS identified and quantified 25 polyphenols, with catechin (28.3 µg/g dry weight), kaempferol (18.14 µg/g dry weight), and isorhamnetin (10.98 µg/g dry weight) as the major compounds. Among the tested extracts, the hydroethanolic extract demonstrated the highest antioxidant activity (IC₅₀ = 2.97 mg/mL), whereas the hydroacetic extract exhibited the lowest (IC₅₀ = 6 mg/mL). All extracts inhibited F. oxysporum growth, with minimum inhibitory concentration (MIC) ranging from 1.20 to 3.20 mg/mL and minimum fungicidal concentration (MFC) from 3.20 to 5.80 mg/mL. These findings highlight L. sulphureus as a promising source of bioactive compounds with antioxidant and antifungal properties, supporting its potential application in pharmaceutical and agricultural fields.

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