Study on secondary metabolites and insecticidal activities of mixed fermentation of two marine fungi

In order to study the secondary metabolites produced by the mixed fermentation of marine fungi Trichoderma harzianum ABC19819 and Penicillium brefeldianum ABC190807, silica gel, Sephadex LH-20 gel and thin-layer chromatography were used to isolate and purify the secondary metabolites produced by the mixed fermentation. The structures of the compounds were identified by ¹H NMR, ¹³C NMR, ESI-MS and compared with the data in the literatures. The activities of the compounds were evaluated using the third instar larvae of Aedes aegypti. The results showed that six known compounds were isolated from the mixed culture fermentation products of the two strains and were identified as Agathic acid ( 1 ), 4-hydroxybenzaldehyde ( 2 ), nafuredin ( 3 ), 4-hydroxy-3,6-dimethyl-2H-pyranone ( 4 ). Mevalonolactone ( 5 ) and brefeldin A ( 6 ), of which compound 1 was isolated for the first time from the mixed culture fermentation products of the two strains. Compounds 1 and 3 showed significant insecticidal activity against the third instar larvae of A. aegypti, with LC₅₀ values of 162 mg/L and 240 mg/L after 72 h of treatment. This study is of great value for obtaining compounds with insecticidal activities through mixed fermentation.