Isolation and identification of secondary metabolites from Aspergillus ustus SN56147 and their inhibitory effects on Botrytis cinerea

Silica gel column chromatography, gel column chromatography and high-performance liquid chromatography were used to isolate and purify secondary metabolites from Aspergillus ustus SN56147. The structures of ten compounds were identified via high-resolution mass spectrometry (HRMS), ¹H NMR, ¹³C NMR, 2D NMR and literature data comparison. Compound 1 (Q-methylalbrassitriol) was characterized as a new sesquiterpenoid, whereas compounds 2-10 were known substances. The mycelial growth rate method was employed to test the antifungal activity against Botrytis cinerea, and wound inoculation and detached leaf assays were conducted to assess the control efficacy of active compounds on strawberry gray mold. The results revealed that compound 3 (6-ethyl-2,4-dihydroxy-3-methylbenzaldehyde) exerted strong inhibitory activity against B. cinerea with an EC₅₀ value of 27.14 μg/mL. At 400 μg/mL, its protective and curative effects on strawberry were 51.85% and 59.26% respectively, close to those of the positive control pyrimethanil, suggesting its promising prospect for further investigation.