Design, Synthesis, Characterization And Antifungal Activity Evaluation Of Heterocyclic Amide Derivatives

Two series of 58 heterocyclic amide derivatives based on carboxylic acids and heterocyclic compounds were designed and synthesized according to the principle of combination of bioactive substructures together. Among them, heterocyclic amide derivatives (series A) contain 28 target compounds and heterocyclic benzamide derivatives (series B) possess 30 target compounds. The structure of every synthesized compound was determined by NMR (1H NMR and 13C NMR) and melt point determination. To date, in series A, compounds A3, A6, A21-A22 and A24-A28 have not been reported; in series B, compounds B1-B7, B10-B11, B13, B17and B19-B30 have not been reported either. The antifungal activity of all synthesized heterocyclic amide derivatives was determined using five plant pathogenic fungi (Gibberella zeae, Helminthosporium maydis, Rhizoctonia solani, Botrytis cinerea and Sclerotinia sclerotiorum) as targets by the method of plate growth rate. Preliminary results have indicated that some of the synthesized target compounds revealed good antifungal activity. Among series A, compound A2 showed the strongest activity and possessed better antifungal activity against Helminthosporium maydi, Botrytis cinerea and Sclerotinia sclerotiorum than carbendazim. In the meantime, compounds Al, A8 and A10 have also displayed excellent antifungal against Helminthosporium maydi, Botrytis cinerea and Sclerotinia sclerotiorum and their inhibition of growth reached above 90% at a concentration of 100 mg/L. Among series B, compounds B3 and B5 had better antifungal activity against Helminthosporium maydis than carbendazim. Compound B16 showed the strongest activity and possessed good antifungal activity against Gibberella zeae, Botrytis cinerea and Helminthosporium maydis at 100 mg/L, which was close to carbendazim. In the meantime, compound B7, B8 and B9 have also displayed excellent antifungal against Botrytis cinerea and Helminthosporium maydis and their inhibition of growth reached above 85% at a concentration of 100 mg/L. In addition, the relationship between concentration and effect showed that for series A, Al, A2, A8 and A10 exhibited remarkale relationship between concentration and effect against Helminthosporium maydis, Botrytis cinerea and Sclerotinia sclerotiorum; for series B, B3, B5, B7, B8, B9 and B16 displayed remarkable relationship between oncentration and effect against Helminthosporium maydis.