| Natural products have been reviewed from several perspectives in the past.Piper sarmentosum is a plant of the Piperaceae belonging to the family of Piperaceae,which is used for both food and medicinal purposes.Various studies demonstarted that the extracts of P.sarmentosum have a certain effect on various agricultural pests and phytopathogenic fungi,but its herbicidal effect has not been explored.The study found that the extract of P.sarmentosum had strong herbicidal activity against barnyard grass and other weeds.Therefore,this study systematically tested the action spectrum and mode of action of the extract of P.sarmentosum on the sensitive weeds,and biological activity tracking method was used to separate and purify the herbicidal activity from the extract of Piper sarmentosum.The chemical structure of the composition was confirmed by the spectral data;the herbicidal activity of each active ingredient of P.sarmentosum against weeds was determined,and the herbicidal active ingredient of P.sarmentosum was preliminarily defined in combination with its chemical structure.The main research results are as follows:1.Extraction of the whole dried powder of P.sarmentosum with ethanol,concentrate the obtained ethanol filtrate by vacuum distillation,and then add ethanol to make a 100mg/mL drug solution.The biological activity assay found that the ethanol extract of P.sarmentosum had a broad herbicidal activity against weeds,among others,it exhibited strong herbicidal activity against Echinochloa crusgalli,Amaranthus tricolor and Chloris virginata.The inhibition rates of root length and shoot length were 92.42%,90.91%,91.41%and 81.15%,63.68%and 87.94%,respectively.The herbicidal activity against barnyard grass was the highest,and the EC500 values of root length and shoot length were0.389 mg/mL and 0.429 mg/mL,the pot test results showed that the test concentration of P.sarmentosum extract was 10 mg/mL,which has a strong control effect on three kinds of weeds.The control effect of E.crusgalli was better than A.tricolor and C.virginata,The control effect was equivalent to decanoic acid.2.Isolate and identify the herbicidal active substances in the ethanol extract of P.sarmentosum using a combination of vacuum distillation,liquid-liquid extraction,silica gel column chromatography,electrospray mass spectrometry（ESI-MS）and nuclear magnetic resonance（NMR）.The ethanol extract of P.sarmentosum was concentrated by vacuum distillation,and the liquid-liquid extraction method was used to determine petroleum ether as the best extraction solvent,and then the petroleum ether extract was further separated by silica gel column chromatography to obtain 10 fractions.The isolate was purified by column chromatography to obtain 4 compounds,respectively.Its chemical structure was identified as piperine,sarmentine,sarmentosine,and pellitorine by MS,1H NMR and 13C NMR.3.To order to clarify herbicidal spectrum,the herbicidal activity of four compounds was measured under the greenhouse test conditions.The test results showed that the four compounds can inhibit the growth of buds and roots of E.crusgalli and A.tricolor in a concentration-dependent manner.The herbicidal activity of sarmentosine was stronger than that of sarmentine.Its EC500 was twice than that of sarmentine,while piperine and pellitorine had weak herbicidal activity.When sarmentine and sarmentosine were 5 and 2.5mg/mL,respectively.E.crusgalli and A.tricolor had strong herbicidal activity.The average inhibition rates of 5 mg/mL sarmentine and 5mg/mL sarmentosine on A.tricolor were 78.64%and 84.73%,respectively,and the average inhibition rates on barnyard grass were 85.22%and 91.45%,respectively.The herbicidal activity of sarmentine and sarmentosine against E.crusgalli was stronger than that of decanoic acid.In order to further clarify the herbicidal activity of sarmentosine,the herbicidal activity of sarmentosine on 12 weeds was measured under greenhouse conditions,including broad-leaved weeds and monocotyledonous weeds.The test results showed that 5 mg/mL sarmentosine had broad herbicidal activity against broadleaf weeds,morning glory,A.tricolor and Abutilon hybridum,and the inhibition rate were exceeded 80%.4.In order to clarify the effect of the mixed use of sarmentine and sarmentosine with the commercial herbicide propanil,15 mixed solutions of different concentrations were prepared by using sarmentine,sarmentosine and propanil,observe the test results after 14days of prevention,the mixtures of 0.5 mg/mL sarmentine and 0.5 mg/mL sarmentosine showed 87.56%and 88.55%inhibition rates on E.crusgalli and A.tricolor,respectively.The inhibition rates of 0.5 mg/mL sarmentosine on E.crusgalli and A.tricolor were56.30%and 48.40%,respectively,The inhibition rates against E.crusgalli and A.tricolor were 56.30%and 48.40%,respectively,while the inhibition rates of 0.5 mg/mL sarmentosine and propanil to E.crusgalli and A.tricolor were 41.78%and 51.33%,respectively,showed that sarmentine and sarmentosine combined with propanil use controllable E.crusgalli and A.tricolor,suggesting a synergistic effect. |
