Synthesis And Antifungal Activities Of Substituted Phenylsulfonylhydrazones Containing Heterocyclic Rings

Phytopathogenic fungi have become deadly disease in agriculture because of their strong infection, and hard to control. Meanwhile, conventional fungicides were faced a critical drug-resistant. Sulfonylhydrazones may show high antifungal activity by their strong ability of coordination with the target active site in microorganism. On the other side, introduction of heterocyclic rings can improve the bioactivity. Therefore, here we synthesized four series of substituted phenylsulfonylhydrazone compounds containing heterocyclic rings as antifungal agents. The conclusion were as follows:1. Twenty substituted phenylsulfonylhydrazones were prepared(twelve new compounds), and their structures were characterizated by mp and 1H NMR. The steric structure of 3d was well determined by single-crystal X-ray diffraction analysis.2. At the concentration of 100 μg/m L, their antifungal activities were evaluated against seven phytopathogenic fungi such as Fusarium graminearum, Alternaria solani, Valsa mali, Phytophthora capsici, Fusarium solani, Botrytis cinerea, and Glomerella cingulata. Compounds 5b, 5d, 13 a, 13 b and 13 d showed good antifungal activity against V. Mali; compounds 13 a and 13 d against showed good antifungal activity F. Graminearum; compounds 5b, 5d and 13 a showed good antifungal activity aganist F. Solani; compound 3d showed good antifungal activity aganist G. cingulata. The inhibition rates of the above-mentioned compounds were all larger than 70%.3. The EC50 values of six tested compounds were all less than those of the positive control hymexazol. It suggested that these compounds showed potent antifungal activities. Structure-activity relationships were observed: introduction of the electron-donating group(e.g., 4-methyl and 4-ethyl) or 4-bromine atom on the phenyl ring improved antifungal activities; whereas introduction of 3-nitro group on the phenyl ring lowered activities; addition of one double bond between the phenylsulfonylhydrazone fragment and the furan ring of 3a,b,d usually gave more active compound 13 a,b,d; introduction of indolyl ring to phenylsulfonylhydrazone led to potent compounds.