Synthesis,Anti-phytophathogenic Fungi Activity And Structure-Activity Relationship Of Cinnamic Ester Analogues

A series of cinnamic acid esters and their analogues including 14 new compounds along with 58 known compounds were synthesized and evaluated for antifungal activities in vitro against four plant pathogenic fungi by using the mycelium growth rate method.Structure-activity relationship（SAR）was derived also.Almost all of the compounds showed some inhibition activity on each of the fungi at 0.5 mM,and of which fifteen compounds showed higher average inhibition rates of 70%–91%for all the fungi.Among them,eight compounds showed the higher average activity with average EC₅₀ values of 17.4–28.6μg/mL for all the fungi than kresoxim-methyl,a commercial fungicide standard,and ten compounds were much more active than commercial fungicide standards carbendazim against P.grisea or kresoxim-methyl against both P.grisea and Valsa mali.Generally,compounds C1 and C2 showed the higher activity on all the fungi(average EC₅₀=17.4,18.5μg/mL)and great potential for development of new plant antifungal agents.SAR analysis showed that both the substitution pattern of the phenyl ring and the alky group in the alcohol moiety significantly influences the activity.There exists complexly comprehensive effect between the substituent on the phenyl ring and the alkyl group in the alcohol moiety on the activity.Thus,cinnamic acid esters may be considered as promising lead compounds for the development of new antifungal agents for plant protection.Further research is necessary on the structural optimization,the determination of an antifungal spectrum and the in vivo activity of these compounds.