Studies On Chemical Constituents And Bioactivity Screening Of The Whole Plant Of Cuscuta Chinensis Herbs

The parasitic plant Cuscuta chinensis herbs is the dry aboveground part of Convolvulaceae Cuscuta chinensis Lam.,is mostly parasitic and twined on leguminosae,flax and other plants.The whole plant with flowers and fruits is used as medicine,which has the effects of tonifying the liver and kidney and benefiting the essence.It is widely used in anti-inflammatory,antioxidant and lipid-lowering,showing a good prospect of clinical utilization.Cuscuta chinensis contains flavonoids,alkaloids and other active components.At the moment,the research on dodder at home and abroad is more thorough,but the research on the chemical components and biological activities of the whole plant is rare.In this study,the medicinal plant Cuscuta chinensis in Xinjiang was selected as the research target,focusing on the chemical components of the whole grass and the screening of its bioactivity.The main research contents are as follows:In the first part,we summarized and analyzed the research on plant chemical components,biological activities,parasitic characteristics and quality standards of Cuscuta Chinensis plants.There were flavonoids,sterols,polysaccharides,lignans,alkaloids,terpenoids and other components in Cuscuta chinensis plants,which had many efficacys such as antioxidation,anti-inflammatory,immune regulation,liver protection,anti-cancer,protecting nerve,lipid-lowering and so on.At present,the research on its quality standard still remained in the relatively simple character,thin layer chromatography,microscopic and other simple methods;In addition,because Cuscuta chinensis is parasitic,its chemical composition would also be directly affected by the host plant,place of origin and climate,and then affected its biological activity.Therefore,it is necessary to pharmacognostical identification,determine the origin,to ensure the safety and stability of the drug efficacy.In the second part,the biological activities such as anti-inflammatory,antibacterial,hypolipidemic and hypoglycemic of Cuscuta chinensis extracts with different polarity were screened,and the antioxidation of Cuscuta chinensis herbs from different producing areas was determined.The results showed that there were antioxidant components in Cuscuta chinensis herbs;The inhibition rate of each part of Cuscuta chinensis to 15-LOX enzyme was not obvious,but had a strong inhibition rate to COX-2 enzyme,among which the anti-inflammatory activity of petroleum ether fraction was the strongest;dichloromethane fraction and ethyl acetate fraction had different degrees of antibacterial effects on streptococcus albicans,staphylococcus aureus and escherichia coli,and also showed strong lipid-lowering activity in vitro;The inhibition rate of all parts of Cuscuta chinensis on PTP1B was relatively low,and the hypoglycemic activity was not high.In the third part,the chemical composition in petroleum ether fraction of Cuscuta chinensis was analyzed by gas chromatography-mass spectrometry（GC-MS）.The results showed that 47components were identified from the petroleum ether part of Cuscuta chinensis,including alkanes,fatty acids,esters and steroids,among them,The contents ofγ-sitosterol（13.85%）,palmitic acid（9.72%）,dibutyl phthalate（7.97%）and rapeseed sterol（6.88%）were high.In the fourth part,32 monomer compounds were isolated from dichloromethane and ethyl acetate fraction in Cuscuta chinensis by silica gel column chromatography,thin layer chromatography,medium pressure rapid preparation chromatography,high performance liquid chromatography and semi preparation liquid.Combined with nuclear magnetic resonance（1DNMR,2DNMR）,electrospray ionization Mass spectrometry（ESI-MS）,ultraviolet spectrum（UV）and other pop chromatography and chromatographic techniques,30 monomer structures were identified,including 10 flavonoids,5 lignans and 1 alkaloid,8 phenols,3 monoterpenes,1amide,1 sterol and 1 spiro compound.The monomer structures were identified as6-ethoxy-1H-pyrimidine-2,4-dione（CD-1）,ethyl 4-hydroxybenzoate（CD-2）,scopoletin（CD-3）,（-）-Loliolide（CD-4）,（+）-pinoresinol（CD-5）,quercetin（CD-6）,kaempferol（CD-7）,N-trans-Feruloyltyramine（CD-8）,（+）-syringaresinol（CD-9）,medioresinol（CD-10）,3,4-dehydrotheaspirone（CD-11）,（+）-pinoresinol-O-β-D-glucopyranoside（CD-14）,Simplexoside（CD-15）,Hydroquinone（CD-16）,vanillic acid（CD-17）,β-daucosterol（CD-18）,methyl 2,4,6-trihydroxybenzoate（CD-19）,kaempferol-3-O-β-D-（6″-p-hydroxybenzoyl）-galactopyranoside（CD-20）,trans-tiliroside（CD-21）,quercetin-3-O-（6″-feruloyl）-β-D-galactopyranoside（CD-22）,kaempferol-3-O-（2′′-O-E-p-coumaroyl）-β-D-glucopyranoside（CD-23）,kaempferol-3-O-β-D-glucopyranoside（CD-24）,isorhamnetin-3-O-β-D-glucopyranoside（CD-25）,roseoside（CD-26）,kaempferol-3-O-（6″-O-E-feruloyl）-β-D-glucopyranoside（CD-27）,vomifoliol（CD-28）,pyrocatechol（CD-29）,E-p-coumaric acid（CD-30）,Z-p-hydroxy-cinnamic acid（CD-31）,hyperoside（CD-32）.Among them,CD-1,CD-3,CD-4,CD-11,CD-15,CD-19,CD-20,CD-21,CD-22,CD-23,CD-26,CD-27,CD-28 and CD-29 were isolated from this plant for the first time.At the same time,the anti-inflammatory activity of some isolated monomer compounds was evaluated by enzyme activity detection in vitro.The results showed that compound CD-22 had good anti-inflammatory activity,the inhibition rate of COX-2 enzyme was 93.86%,and the measured IC₅₀ value was 0.32±0.01μM.In the fifth part,the high performance liquid chromatography（HPLC）fingerprints of Cuscuta chinensis herbs from ten producing areas（S1～S10）were established,and a total of 12common chromatographic peaks were calibrated.The samples were analyzed by similarity analysis,principal component analysis and cluster analysis by SPSS 19.0 software.The similarity results showed that the similarity of samples S1,S2,S3,S6,S7,S9 and S10 was higher than 0.90,while the similarity of S4,S5 and S8 was lower than 0.90.The results of principal component analysis and cluster analysis showed that the samples were divided into two categories,S1,S2,S3,S6,S7,S9 and S10 are grouped into one class,while S4,S5 and S8 of other producing origins are grouped into one class;At the same time,the contents of hypericin,astragalin and quercetin were determined.The results showed that there were significant differences in the content of flavonoids in Cuscuta chinensis from different producing areas.The RSD of precision,repeatability and stability were less than 3%,and the average recovery was more than 95%.It provided a reference basis for the study of the quality standard of Cuscuta chinensis herbs.