Fractionation of an EtOAc-soluble partition of a solid fermentation of the endophytic fungus Trichoderma orarium 18F0041 resulted in the isolation of two new compounds, a γ-lactone, 5-hydroxy-3-(methoxymethyl)-4-methylfuran-2(5H)-one (1), and a methylpentanoid derivative, 5-ethoxy-4-hydroxy-3-methyl-5-oxopentanoic acid (2). Additionally, two further metabolites were also isolated for the first time from a natural source, namely 2-hydroxypyridin-3-yl acetate (3) and (+)-rel-(4S,5S)-4,5-dihydroxytetrahydro-2H-pyran-2-one (4). All structures were elucidated on the basis of extensive analyses of spectroscopic data and comparison with literature data. Their antifungal activity was also evaluated. Our results showed that some of the constituents possessed mild antifungal activity against Fusarium sp. LC8, Neopestalotiopsis sp. BCRC 35002, and Colletotrichum gloeosporioides BCRC 35178. Previously, δ-valerolactone derivatives were rarely reported in the genus Trichoderma. The discovery of these compounds in the fermentation products of this new Trichoderma species is therefore highly significant. Natural products of Trichoderma warrant further investigation as potential antifungal agents for biocontrol applications.

Keywords：Trichoderma orarium 18F0041 δ-valerolactone Antifungal Secondary metabolites