Research On Antifungal Activity Of Enzimidazolone Amide Derivatives

The antimicrobial activity of benzimidazolone amide derivatives was reported seldomand there was no report about its mechanism of action. A series of benzimidazolone amidederivatives were synthesized in this research, and their antimicrobial activity against severalstrains of plant pathogenic fungi, mode and mechanism of action were preliminary studied.1. Fourteen benzimidazolone amide derivatives were synthesized fromo-phenylenediamine and acetoacetic ester. Their structures were confirmed by1H-NMR,13C-NMR, and ESI-MS spectral analysis, respectively. The antifungal activity of testedcompounds against Botrytis cinerea was evaluated through pendant-drop method. The resultsindicated that compounds IV-01, IV-02, IV-03and IV-11, as well as IV-02a, thede-isopropenyl products of IV-02, had good inhibitory effect against B. cinerea. The EC50values of the most potential compounds IV-02and IV-02a against Botrytis cinerea were1.337and0.559μg/mL, respectively.2. Forty six N-acylated derivatives of ethyl2-oxo-1-isopropyl-benzimidazole-5(or6)-carboxylate were synthesized from m-amino benzoic acid. The structures of the newderivatives were confirmed by1H-NMR,13C-NMR spectral analysis. Antimicrobial activitytest through pendant-drop method indicated that compounds8a-22,10b-16,8a-05, and10b-04had good inhibitory action against Botrytis cinerea at50μg/mL.3. Antimicrobial activity of compounds IV-02and IV-02a against Verticillium dahliae,Fusarium oxysporum f. sp. Vasinfectum, Colletotrichum gloeosporioides, Botrytis cinerea andFusarium graminearum were tested through mycelial growth rate and pendant-drop method.Various degrees of inhibitory effect were observed in the treatments of spore germination andmycelial growth against different fungi, in which B. Cinerea was more sensitive to thecompounds than other strains. In addition, the tested compounds exhibited more strongtoxicity of spore germination than that of mycelium growth.4. Antifungal activities of compound8a-22against the five strains of plant pathogenicfungi were evaluated by the methods of mycelium growth and pendant-drop, respectively.The results indicated that compound8a-22showed could inhibit spore germination andmycelial growth of all tested fungi at the tested concentration. Compound8a-22showed better inhibitory effect on spore germination, and its EC50value against B. cinerea was11.142μg/ml.5. To evaluate the control effects against tomato gray mould (Botrytis cinerea), a potexperiment of formulated IV-02a was carried out. The results indicated that the protective andcure chemical of compound IV-02a are more than65%at the tested concentration. It wasmore suitable to use as a protective chemical than cure chemical, and its protective effect was90.41%. Furthermore, no phytotoxicity was observed in the experiment.6. Inhibition of fungicidal activity of compounds IV-02a and8a-22by the addition ofsaccharides, fatty acids and lipid against B. cirerea were tested through pendant-drop method.The results indicated that glucose could reduce their antifungal activity extraordinarilywhereas the addition of fatty acid salts and lipid had no effect on their antimicrobial activity.Thus we hypothesized that this type of chemicals might be a respiration inhibitor.