Phytotoxicity of secondary metabolites from a fungal endophyte Muyocopron laterale isolated from leaves of Centella asiatica

An endophytic fungus isolated from the leaves of a common medicinal plant, Centella asiatica, was identified as Muyocopron laterale through molecular means. The fungus was cultured in potato dextrose broth medium. After five weeks, the broth and mycelium were extracted with EtOAc. Chromatographic separation of the combined EtOAc extract yielded two new polyketides, named muyokopyrone (3) and muyokoenone (5), along with four known compounds, austdiol (1), 4-(hydroxymethyl)-3-methoxy-5-methylcyclopent-2-enone (2), eugenitin (4) and 6-methoxymethyl eugenin (6). The fermentation broth showed necrotic and wilting symptoms when sprayed on the leaves of cucumber (Cucumis sativus) plants. The EtOAc extracts of the broth and mycelium showed necrotic symptoms in the leaf puncture assay using cucumber leaves. The EtOAc extract of the broth inhibited root and shoot elongation with IC₅₀ values of 23.7 μg/mL and 55.8 μg/mL, respectively in the lettuce seed germination assay. Compound 1 inhibited root elongation of lettuce seeds with an IC₅₀ value of 5.38 μg/mL while compounds 1 and 2 showed necrotic symptoms in the leaf puncture assay.