Valorization of durian shell waste: antifungal activity of ethanol extract against Penicillium expansum and its underlying mechanisms.

Durian shells contain abundant antimicrobial active substances, representing an underutilized resource for controlling postharvest pathogens. This study evaluated the antifungal activity of durian shell ethanol extract (DSEE) against several postharvest pathogenic fungi and explored its underlying mechanism. LC-MS analysis revealed that DSEE is rich in flavonoids, phenolics, and alkaloids. In vitro experiments demonstrated that DSEE significantly inhibited the mycelial growth of Botrytis cinerea, Fusarium oxysporum, Cladosporium cladosporioides, Penicillium digitatum, P. expansum, and P. italicum. Notably, DSEE at 0.25 mg/mL reduced the radial growth and patulin production of P. expansum by 93.9% and 99.8%, respectively, while 0.5 mg/mL completely inhibited both fungal growth and patulin accumulation. In addition, DSEE treatment markedly reduced sporulation and pathogenicity, and disrupted membrane integrity, as evidenced by increased leakage of proteins and nucleic acids. Molecular docking predicted that eight active components possess strong binding affinities with key transcription factors (AbaA, BrlA, PacC, PatL) in P. expansum. Among these components, sinapic acid exhibited the strongest antifungal activity, reducing patulin production by 99.7% at 5 mg/mL and significantly downregulating genes involved in fungal growth, sporulation, and patulin biosynthesis. Overall, this study provides a theoretical basis for the high-value utilization of durian shell waste in sustainable food preservation.