Identification of Cyclic Dipeptides and a New Compound (6-(5-Hydroxy-6-methylheptyl)-5,6-dihydro-2-pyran-2-one) Produced by against .

As an important microbial resource, , especially have important application values in medicine and biotechnology. SYH3 was isolated from soil samples in tomato-growing areas and showed good inhibitory effects on in tomato. To obtain pure active compounds, SYH3 fermentation broth was subjected to XAD-16 macroporous resin and silica gel column chromatography. Combined with the repeated preparation and separation of preparative high-performance liquid chromatography (HPLC), a total of four monomer compounds were obtained after activity tracking. Compound was identified as a new six-membered lactone ring compound named 6-(5-hydroxy-6-methylheptyl)-5,6-dihydro-2-pyran-2-one by 1D and 2D nuclear magnetic resonance (NMR) data and mass spectrometry (MS). The other three active compounds belong to the cyclodipeptide, and their half maximal inhibitory concentration (IC) values against were 43.4, 42.9, and 30.6 μg/mL, respectively. Compound significantly inhibited the spore germination and induced swollen and deformed local hyphae of with an IC value of 24.9 μg/mL. Compound also had broad-spectrum antifungal activity and had a good antifungal effect on the tested plant-pathogenic fungi. The modes of action of new compound () still require further investigation, representing a novel and effective anti-fungal agent for future application.