Study On Design,Synthesis And Herbicidal Activity Of Ferulic Acid Derivatives

Natural active substances have gradually become an important resource for developing herbicides with new modes of action.Based on natural products or their derivatives,it is of great significance to create new herbicides with high efficiency and environmental friendliness for comprehensive control of weeds.Ferulic acid is a natural compound with wide biological activities,which has the functions of sterilization,insecticide,weeding,antivirus and anti-inflammation,and is widely used in medicine and pesticide fields.In order to create new herbicides with high efficiency,low toxicity,and eco-friendly,a series of ferulic acid derivatives with novel structures were designed and synthesized by structural modification based on ferulic acid.Taking five plants including Digitaria sanguinalis,Echinochloa crusgalli,Amaranthus retroflexus,Cucumis sativus,Lactuca sativa and Lycopersicon esculentum as target organisms to study the herbicidal activity of target compounds by using small cup method and stem and leaf spray method.The specific conclusions are as follows:1.There were 39 ferulic acid amides(series A target compounds)were synthesized by acetylation and amidation with ferulic acid as starting material.After deprotecting the phenolic hydroxyl group of the intermediate compound,the intermediate compound was substituted with methyl bromoacetate under the conditions of K2CO3 as acid-binding agent and DMF as solvent.The ester compound was hydrolyzed into acid and then esterified with n-butanol under the catalysis of concentrated sulfuric acid,and 14 new ferulic acid derivatives(series B target compounds)were synthesized.The structures of all compounds were characterized by 1H NMR,13C NMR and HRMS,and the chemical structures of representative compounds were confirmed by X-ray single crystal diffraction analysis.2.The herbicidal activity of the target compounds and their intermediates was determined by small cup method.The determination results of target compounds of series A showed that most of the compounds showed good inhibitory activity against the tested plants under the concentration of 400 μg/mL.Compounds Ⅳ-4,Ⅳ-26 and Ⅳ-28 have strong inhibitory effects on the roots of D.sanguinali,with inhibition rates of 91.03%,79.22%and 82.86%,respectively.The inhibitory activity of compound Ⅳ-2 on E.crusgalli root growth was 70.57%.The inhibitory activities of compounds Ⅳ-10,Ⅳ-27 and Ⅳ-38 against A.retroflexus root were 83.01%,75.65%and 79.19%.The inhibitory activities of Ⅳ-7 and Ⅳ-15 on C.sativus root growth were 74.38%and 81.82%.The determination results of series B target compounds showed that at the concentration of 400μg/mL,the inhibition rates of compound Ⅷ-8 on the roots and stems of D.sanguinali reached 59.66%and 51.51%,and the inhibition rates of compound Ⅷ-1 against the stems of D.sanguinali was 67.16%,while compounds Ⅷ-2 and Ⅷ-14 against the root and stem of growth inhibition rate of A.retroflexus were 84.36%,53.13%and 68.92%,63.13%,respectively.Furthermore,at the concentration of 400 μg/mL,compounds Ⅷ-3,Ⅷ-4 and Ⅷ-5 showed better activity against L.sativa root and fresh weight,and the inhibition rate were 70.77%,57.54%,76.29%,66.58%and 70.55%,57.96%,and the inhibition rates of compound Ⅷ-13 on the roots of L.sativa was 84.28%.In addition,the inhibition rates of compounds Ⅷ-7 and Ⅷ-11 on the growth of S.lycopersicum were 76.28%and 80.33%,respectively.After further exploring of the herbicidal effect of the target compounds,it was found that the IC50 value of compound Ⅳ-4 on the roots of D.sanguinali was 97.68 μg/mL,which was obviously better than the growth inhibition effect on the stem of D.sanguinali.The IC50 value of Ⅳ-27 against A.retroflexus root was 207.52 μg/mL.Compound Ⅳ-15 showed better growth inhibition activity on C.sativus roots with an IC50 value of 184.45μg/mL.And the IC50 value of Ⅷ-8 and Ⅷ-14 against the root of D.sanguinali and A.retroflexus were 269.44 and 187.16 μg/mL,respectively.As for compound Ⅷ-4,which IC50 value was 178.79 μg/mL against the root of L.sativa.Compound Ⅷ-7 showed better growth inhibition on S.lycopersicum roots with an IC50 value of 179.49 μg/mL.3.Further observations under an optical microscope found that compound Ⅳ-4 caused significant changes in the cell structure of D.sanguinali roots,resulting in cell tissue dissolution and root hair reduction.4.The results of the trypan blue staining method found that the roots cells of D.sanguinali died a lot after compound Ⅳ-4.