Secondary metabolites isolated from Trichoderma hamatum b-3 and their fungicidal activity.

An undescribed trichodenone derivative (1), two new diketopiperazines (3 and 4) along with a bisabolane analog (2) were isolated from Trichoderma hamatum b-3. The structures of the new findings were established through comprehensive analyses of spectral evidences in HRESIMS, 1D and 2D NMR, Marfey's analysis as well as comparisons of ECD. The absolute configuration of 2 was unambiguously confirmed by NMR, ECD calculation and Mo2(AcO)4 induced circular dichroism. Compounds 1-4 were tested for their fungicidal effects against eight crop pathogenic fungi, among which 1 showed 51% inhibition against Sclerotinia sclerotiorum at a concentration of 50 µg/mL.