Chalcone derivatives containing thiazole fragment: Synthesis and antifungal activity

28 chalcone derivatives containing thiazole fragment were synthesized. The results of antifungal bioactivity tests suggested that most of the compounds possessed superior in vitro antifungal activities against nine plant pathogenic fungi. T17 showed excellent bioactivity against Sclerotinia sclerotiorum (S. sclerotiorum) with an EC50 value of 12.9 μg/mL, which was better than that of azoxystrobin (15.1 μg/mL). Further than that, T11 exhibited good bioactivity against Phytophthora capsici (P. capsici) with an EC50 value of 15.8 μg/mL, which was superior to that of azoxystrobin (40.2 μg/mL). The bioactivity test was carried out in oilseed rape in vivo. The protective and curative activities of T17 on oilseed rape infected with S. sclerotiorum were 86.5 and 75.2%, respectively, which were higher than those of azoxystrobin (71.4 and 68.6%) at 200 μg/mL. Scanning electron microscopy results indicated that the mycelium collapsed and folded after T17 treatment, which changed the mycelial morphology, inhibiting the growth of mycelium, thus achieving an inhibitory effect on S. sclerotiorum. In addition, the mechanism of action studies manifested that the results were further verified by performing in vivo antifungal activity assay, fluorescence microscopy, light microscopy, cell membrane permeability, leakage of cellular contents, and malondialdehyde content assay. This study demonstrates that compound T17 has the potential to become a novel fungicide.