Study On The Bioactive Constituents Of Praxelis Clematidea

Praxelis clematidea（Griseb.）R.M.King&H.Rob belongs to the genus of Praxelis in Compositae family.It is an annual herb.The origin of P.clematidea is South America,and mainly distributes in Guangdong,Fujian,Hainan,Hong Kong and other tropical or subtropical coastal areas in China.Nowadays,it has become a kind of foreign malignant weed with great destructive potential,which has caused serious ecological environment damage and economic loss to the invasion area.In this paper,the chemical components of the whole plant of P.clematidea were studied.75%Ethanol extract was extracted with different polar solvents successively,and the chloroform fraction was furtherly studied.Eight-two compounds were isolated and purified by silica gel column chromatography,ODS MPLC,Sephadex LH-20 and preparative HPLC.Various chemical and spectroscopic data analysis were utilized to identify their chemical structures.They were elucidated and identified as:（1.Flavonoids）5-hydroxy-7,4’-dimethoxyflavone（1）,4’,5-dihydroxy-7-methoxyflavone（2）,luteolin-7,3’,4’-trimethyl ether（3）,4’-hydroxy-5,7-dimethoxyflavone（4）,7-hydroxy-5,4’-dimethoxyflavone（5）,5,7,4’-trimethoxyflavone（6）,5,7,3’,4’-tetramethoxyflavone（7）,4’-hydroxy-5,7,3’-trimethoxyflavone（8）,5,6,7,4’-tetramethoxyflavone（9）,4’-hydroxy-5,6,7-trimethoxyflavone（10）,7-hydroxy-5,6,4’-trimethoxyflavone（11）,6-hydroxy-5,7,4’-trimethoxyflavone（12）,7,4’-dihydroxy-5,6-dimethoxyflavone（13）,cirsimaritin（14）,hispidulin（15）,jaceosidin（16）,6-hydroxy-5,7,3’,4’-tetramethoxyflavone（17）,7,3’-dihydroxy-5,8,4’-trimethoxyflavone（18）,6,7,8,3’,4’-pentamethoxyflavone（19）,3,5,6,7,4’-pentamethoxyflavone（20）,（S）-7,4’-dihydroxy-3’-methoxyflavanone（21）,（S）-liquiritigenin（22）,（S）-naringenintrimethylether（23）,（S）-4’-hydroxy-5,7-dimethoxydihydroflavone（24）,8-hydroxy-6,7,4’-trimethoxyflavanone（25）,（-）-trans-4’-hydroxy-5,6,7-trimethoxy-dihydroflavonol（26）,flavokawain A（27）,flavokawain C（28）,4,2’-dihydroxy-4’,5’,6’-trimethoxychalcone（29）;（2.Phenylpropanoids）cinnamic acid（30）,coniferaldehyde（31）,p-hydroxycinnamic acid（32）,ferulic acid（33）,cinnamic acid（34）,ethyl caffeate（35）,（E）-3-（4-hydroxy-3-methoxyphenyl）prop-2-enoicacid-（1,2-dihydroxycyclohexyl）-4-ester（36*）,（-）-1-[2-（1,2-dihydroxy-1-methylethyl）-2,3-dihydro-6-hydroxy-5-benzofuranyl-ethanone（37）,（-）-（7R,8S,7’E）-4-hydroxy-3,5,5’,9’-tetramethoxy-4’,7-epoxy-8,3’-neolign-7’-en-9-ol（38）,（7S,8R）-ficusal（39）,（7S,8R）-balanophonin（40）,（7’R,8’S）-4,5,3’,4’-tetrahydroxy-2,7’-cyclolign-7-ene-9,9’-dioic acid diethyl ester（41*）,4-[（3S）-（4-hydroxy-3,5-dimethoxyphenyl）-（2S）-hydroxymethyl-8-methoxy-2,3-dihydrobenzo-[1,4]dioxin-6-yl]-（3E）-buten-2-one（42*）,（+）-erythro-syringylglycerol-β-O-4’-sinapyl ether（43）,（+）-xanthiumnolic A（44）,（-）-evofolin B（45）,（+）-（7’R,8R,8’S）-4,4’,9’-trihydroxy-3,3’-dimethoxy-7,9’-epoxylignan-7-one（46）,（-）-（7’S,8S,8’R）-4,4’-dihydroxy-3,3’,5,5’-tetramethoxy-7’,9-epoxylignan-9’-ol-7-one（47）,（-）-syringaresinol（48）,（-）-（7R,7’R,7’’R,8S,8’S,8’’S）-4’,4’’-dihydroxy-3,3’,3’’-trimethyl-pentametho xy-7,9,7’,9’-diepoxy-4,8’’-oxy-8,8’-sesquineolignan-7’’,9’’-diol（49）,（-）-（7R,7’R,7’’R,8S,8’S,8’’S）-4’,4’’-dihydroxy-3,3’,3’’,5,5’-pentamethoxy-7,9,7’,9’-diepoxy-4,8’’-oxy-8,8’-sesquineolignan-7’’,9’’-diol（50）,（+）-（7R,7’R,7’’R,8S,8’S,8’’S）-4’,4’’-dihydroxy-3,3’,3’’,5,5’,5’’-hexa-methoxy-7,9,7’,9’-diepoxy-4,8’’-oxy-8,8’-sesquineolignan-7’’,9’’-diol（51）,（-）-（7R,7’R,7’’S,8S,8’S,8’’S）-4’,4’’-dihydroxy-3,3’,3’’-trimethyl-pentametho xy-7,9,7’,9’-diepoxy-4,8’’-oxy-8,8’-sesquineolignan-7’’,9’’-diol（52）,（-）-（7R,7’R,7’’S,8S,8’S,8’’S）-4’,4’’-dihydroxy-3,3’,3’’,5,5’-pentamethoxy-7,9,7’,9’-diepoxy-4,8’’-oxy-8,8’-sesquineolignan-7’’,9’’-diol（53）,（-）-（7R,7’R,7’’S,8S,8’S,8’’S）-4’,4’’-dihydroxy-3,3’,3’’,5,5’,5’’-hexamethoxy-7,9,7’,9’-diepoxy-4,8’’-oxy-8,8’-sesquineolignan-7’’,9’’-diol（54）;（3.Terpenes）loliolide（55）,isololiolide（56）,isodauc-6-ene-10β,14-diol（57）,trilobolide-6-O-methacrylate（58）,trilobolides-6-O-isobutyrate（59）,wedelolide F（60）,wedelolides A（61）,wedelolides B（62）;（4.Alkaloids）indole-3-carboxaldehyde（63）,3-（hydroxyacetyl）indole（64）,（1H-indol-3-yl）oxoacetic acid methyl ester（65）;（5.others）（R）-5-hydroxy-6-acetyl-2-（1,2-hydroxy-1-methyl）benzofuran（66*）,（S）-11-hydroxy-10,11-dihydroeuparin（67）,1-{2-[（1S,4S）-7-acetyl-4,8-dihydroxy-4-hydroxymethyl-1,2,3,4-tetrahydrodibenzo[b,d]-furan-1-yl]-5-hydroxy-1-benzofura-6-yl}ethanone（68*）,1-{2-[（1R,4S）-7-acetyl-4,8-dihydroxy-4-hydroxymethyl-1,2,3,4-tetrahydrodibenzo[b,d]furan-1-yl]-5-hydroxy-1-benzofuran-6-yl}ethanone（69*）,methyl 4-[3-oxo-2-（2’-pentynyl）-4-cyclopentenyl]butyrate（70*）,4-[3-oxo-2-（2-pentynyl）-4-cyclopentenyl]octanoate（71）,（S）-4-methyl octanoate-2-en-1,4-olide（72*）,（S）-hydroxydihydrobovolide（73）,3-hydroxy-5,6-epoxy-7-megastigmen-9-one（74）,（3R）-4-[（2R,4S）-2-hydroxy-2,6,6-trimethyl cyclohexylidene]-3-buten-2-one（75）,ethyl 3,4-dihydroxybenzoate（76）,ethyl 3,4-dihydroxyphenylacetate（77）,1,2-diol-4-cyclohexylbenzoate（78）,vanillin（79）,isovanillic acid（80）,anillic acid（81）,syringic aldehyde（82）.Among them,the eight compounds 36,41,42,66,68-70,72 were eight new compounds.In this paper,the content of the total flavonoids of the extract and the extraction layers of P.clematidea were also analyzed.The total flavonoids content of the 75%Ethanol extract and the ethyl acetate fraction were 75.43±3.74 mg/g and 296.47±6.59 mg/g,respectively.The contents of flavonoid 2,9,25 in the ethyl acetate fraction were 41.25±2.12 mg/g,23.40±0.40 mg/g and 30.30±2.25 mg/g,respectively,analyzed by UPLC-DAD.On the basis of chemical study,the anti-inflammatory and hypoglycemic activities of some compounds were evaluated in vitro.Compared with the positive control minocycline(IC₅₀=23.15±1.04μM),compounds 35,38,40,44,49,52,68,69 and 71 indicated stronger inhibitions on NO release in LPS-induced BV-2 microglia cell and exhibited significant anti-neuroinflammatory activity.Among them,compound 71 had the strongest activity with the IC₅₀ value of 10.56±1.02μM.And the biological activities of the new compounds 42,68,69were further confirmed by immunoblotting,qRT-PCR and immunofluorescence staining assays.Meanwhile,hypoglycemic activities of the 29 flavonoids were also measured,and the results showed that some flavonoids exhibited considerableα-glucosidase inhibitory activity,of which the inhibition of compound 16 was the most significant,with the IC₅₀0 value of 260.36±21.03μM.This study provided a scientific data for the resource utilization of the foreign malignant weed P.clematidea,and also supplied a chemical baiss for its further development in medicine.