| The development and utilization of microbial herbicides is one of the focuses of current herbicide research.In order to obtain novel herbicidal active substances,this research is based on the secondary metabolites of Pythium aphanidermatum.The 4-hydroxy-3-methoxycinnamic acid is structurally modified and a total of 27 compounds are obtained;Using Echinochloa crusgalli,Digitaria sanguinalis,Amaranthus retroflexus,Brassica napus as test plants,and 97% atrazine as a positive control.The herbicidal activity of the compounds are measured by small cup method and stem-leaf spray method.The main research contents are as follows.(1)By transforming 4-hydroxy-3-methoxy cinnamic acid,we have gotten 27 compounds,which are obtaining esterification,amidation,substitution at the 5-position of a benzene ring,etc.The structures are determined by nuclear magnetic resonance spectroscopy.Ferulic acid is reacted with methanol,n-propanol,isopropanol,glycerol by esterification,obtain ester compounds 1,4,5,6,7,8,9,10;Triethylamine is used as an acidbinding agent,DMF is used as a dehydrating agent,and BOP(Cartesian condensing agent)is used as catalyst to perform amidation of ferulic acid with aniline and aniline derivatives to obtain ferulic acid amides,obtain compounds 16,18,19,20,21,22,23,24,25,26,27;Electrophilic substitution reaction at position 5 of the phenyl ring obtain compounds 2,11 and 13;Condensation reactions with vanillin,acetone,malonic acid,etc.,are carried out to obtain other ferulic acid compounds 3,12,14,15,and 17.(2)The herbicidal activity of the above 27 compounds was preliminary screened by using small cup method and stem-leaf spray method,and ten compounds with herbicidal activity are initially identified.The results of small cup method shows that compounds 2,4,5,10,17,27 have good inhibitory effect on the root of A.retroflexus,and the inhibition rates are 68.33%±2.36%,72.00%±9.93%,68.00%±6.38%,80.67%±4.03%,62.02%±1.71%,70.44%±8.37%;Compounds 26 and 27 have inhibitory effects on the stems of E.crusgalli,and the inhibition rates are 63.46%±7.68% and 62.38%±2.17%;Compounds 7 and 8 have inhibitory effect on D.sanguinalis,the inhibiting rates are 67.33%±3.30% and 75.67%±6.13%.The inhibitory effect of compound 16 on stems of D.sanguinalis is better then others,and the inhibition rate is 67.48%±1.4%;Compounds 16,18,and 19 have the strongest inhibitory effects on B.napus roots,and the inhibition rates are 87.32%±2.29%,88.68%±2.24%,and 84.24%±0.38%.The stem-leaf spray method shows that compound 3 has a higher inhibition on the overground part of B.napus and the inhibition rate is 63.93%±2.33%.Other than the inhibitory rates of compounds 16 and 19 on the overground part of the E.crusgalli are 61.46%±1.74% and 60.55%±1.47%.(3)The compounds are diluted with 5 concentration gradients,and the rescreening of the herbicidal activity was performed using a small cup method and a stem-leaf spray method.The results of the small cup method shows that compounds 4,5,6,8,9,10,19,24 and 27 have better inhibitory effect on roots then stems of the A.retroflexus.And the IC50 of compound 19 against the root of D.sanguinalis is 122.39 mg/L;the IC50 of Compound 19,24 and 27 against the root of B.napus are 86.42 mg/L,103.64 mg/L,and 157.68 mg/L.The results of stem-leaf spray method shows that: compound 3 have growth inhibitory effects on the shoots of A.retroflexus and B.napus,and it also causes the edges of leaves withered.The IC50 for the growth inhibition of the above two plants are 350.86 mg/L and 364.93 mg/L.(4)The safety of nine compounds to Triticum aestivum and Zea mays are determined by small cup method.When the compounds concentration are 200 mg/L,with the exception of compounds 8 and 9,the tested compounds have no significant inhibitory effect on T.aestivum and Z.mays. |
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