Isolation and antimicrobial activities of ascochlorin and its analogues from the metabolites of Cylindrocarpon olidum W1

Eight compounds W1-1–W1-8 were isolated from the secondary metabolites of Cylindrocarpon olidum W1, which is an endophytic fungus from Euonymus japonica, by silica gel column chromatography and pre-HPLC techniques. Based on the 1H NMR and 13C NMR and HRMS-MS data, as well as the published literatures, these chemicals were identified as Ilicicolin A (W1-1), 5-Chlorocolletorin B (W1-2), Ilicicolin B (W1-3), Deacetylchloronectrin (W1-4), Ilicicolin C (W1-5), Ascochlorin (W1-6), Cylindrol A4 (W1-7) and Cylindrol B (W1-8). The obtained Ascochlorin and its analogues showed strong antibacterial activities against Ralstonia solanacearum, with minimum inhibitory concentrations (MICs) of 6.25, 3.13, 100, 3.13, 6.25, 12.5, 25 and 25 μg/mL, respectively. Compounds W1-2, W1-4 and W1-5 could also effectively inhibit the mycelial growth of plant pathogenic fungi Botrytis cinerea and Sclerotinia sclerotiorum. Their medium inhibitory concentrations (IC50) against B. cinerea were 36.45, 21.60 and 26.69 μg/mL, respectively. Their IC50 values against S. sclerotiorum were 20.21, 16.79 and 12.11 μg/mL, respectively.