Study On Agricultural Activity Of Astragalus Complanatus And Ailanthus Altissima

In this paper,the chemical constituents and agricultural activity of the aerial parts of Astragalus complanatus and the root barks of Ailanthus altissima were systematically studied.21 compounds were isolated from the above two plant materials by solvent-dip extraction,liquid-liquid extraction,silica gel column and gel column chromatography and medium-high pressure reverse phase preparative separation,their antibacterial activities and herbicidal activities were evaluated.The main findings obtained are as follows:（1）Using silica gel chromatography and LH-20 gel chromatography,9 compounds were isolated from the methanol extract of the aerial parts of A.complanatus:β-sitosterol（1）,β-sitostenone（2）,lawsaritol A（3）,5,8-Epidioxy-5α,8α-ergosta-6,22E-dien-3β-ol（4）,3’,7-dihydroxy-2’,4’-dimethoxy isoflavan（5）,D-1-O-methyl inositol（6）,complanatuside（7）,7-hydroxy-2’,3’,4’,5’-tetramethoxyisoflavan（8）,daucosterol（9）.All of the above compounds were isolated from the aerial parts of A.complanatus for the first time,and compound 8 is a new compound.（2）The results of antibacterial activity assay of paper disc diffusion method showed that compounds 5 and 8 had different inhibitory effects on Bacillus cereus,Escherichia coli,Staphylococcus aureus,Pseudomonas syringae pv.Actinidiae and Ralstonia solanacearum.The inhibitory activity of compound 5 on these five bacteria was higher than that of 8,and compound 5 also showed some inhibition on Bacillus subtilis and Erwinia.carotovora,while compound 7 showed only little activity against R.solanacearum.The results of micro-broth dilution method showed that the MIC values of compound 5 against P.syringae pv.Actinidiae,R.solanacearum,E.carotovora,B.cereus,E.coli,S.aureus and B.subtilis were 37.5μg/mL,18.8μg/mL,75μg/mL,37.5μg/mL,37.5μg/mL,18.8μg/mL,and 75μg/mL,respectively;Compound 8 against P.syringae pv.Actinidiae,R.solanacearum,B.cereus,E.coli,S.aureus were 75μg/mL,75μg/mL,75μg/mL,75μg/mL,and 150μg/mL,respectively.（3）According to the activity tracking method,12 compounds were isolated from the methanol extract of root bark of A.altissima by silica gel column chromatography and medium-high pressure liquid phase separation.The structures of 11 known compounds were identified as:dehydroailanthinone（10）、daucosterol（11）、ailanthone（12）、erythro-and threo-1-（4-hydroxy-3-methoxyphenyl）-2-{4-[（E）-3-hydroxy-1-propenyl]-2-methoxyphenoxy}-1,3-propanediol（13）、1-（4-hydroxy-3-methoxy）phenyl-1,2,3-propanetriol（14）、Δ^13,18-glaucarubolone（16）、vanillic acid（17）、13,18-dehydroglaucarubinone（18）、glaucarubinone（19）、amphicoside（20）、canthin-6-one-1-O-β-D-apiofuranosyl-（1→2）-β-D-glucopyranoside（21）,the structure of compound（15）has not been determined.Compounds 13,14,and 17 were isolated from the plant for the first time.（4）The herbicidal activities of compounds 10,12,16,18,and 19 against Amaranthus retroflexus and Eleusine indica（L.）Gaertn.were determined by the plate method.The results showed that the inhibitory activity against A.retroflexus was 10>12>19>18>16;the inhibitory activity against E.indica（L.）Gaertn.was 18>19>12>10>16.（5）The results of the plate method showed that the methanol extract of root bark of A.altissima had a root length inhibition rate of about 90%on Brassica napus L.,A.retroflexus,E.indica（L.）Gaertn.and Digitaria sanguinalis at 500μg/mL.The results of pot experiment showed that the effect of methanol extract on A.retroflexus and A.theophrasti Medicus was more obvious by soil treatment,while the effect on Setaria viridis and D.sanguinalis was more obvious by the method of stem and leaf spray.The bioassay results of de-emergence wheat method showed that the methanol extract had a significant inhibitory effect on the plant height and fresh weight of wheat when its concentration is≥500μg/mL,while the inhibition of wheat root length was more obvious when its concentration is 100μg/mL;the safety of soil treatment method for crops was:wheat>corn>rapeseed,which was the most toxic to rapeseed,and the inhibition rate of rapeseed germination was up to 100%at a concentration of 2.56 g/m²;the safety of the stem and leaf spray method for crops was the same as the results of soil treatment,indicating that the methanol extract obtained from root bark of A.altissima is more suitable for monocot crop fields.（6）In addition,the effects of compounds 10 and 12 on the cell density and pigment content of Chlamydomonas reintmrdti were determined.The results showed that compounds10 and 12 had a strong inhibitory effect on the cell density of C.reinhardtii,and compound12 had stronger inhibition.The inhibitory effect of compound 10 on the cell density of C.reinhardtii was more obvious at 24 h than at 6 h,while compound 12 was the opposite;both compounds can promote the growth of chlorophyll a,chlorophyll b and total carotenoids in C.reinhardtii at low concentration.When the concentration is≥5μg/mL,the chlorophyll a,chlorophyll b and total carotenoids content in C.reinhardtii can be inhibited,and the inhibitory effect increases as the concentration of the agent increases.Overall,this compound had the greatest effect on the content of chlorophyll b,followed by total carotenoids,which had the least effect on the content of chlorophyll a,and the effect was more obvious at 24 h than at 6h after administration.