Synthesis And In Vitro Antioxidant Activity Study Of Hydroxylated Of Derivatives Daidzein

Oxidative stress occurred when the antioxidant system could not eliminate the excess radicals produced by the body.It was considered to be an important factor in the development of aging and various diseases,such as cancer,inflammation,acute mountain sickness,neurodegenerative diseases and cardiovascular diseases.Antioxidants,which had ability of relieving oxidative stress by scavenging radicals,could be used to treat related diseases.Isoflavone compounds were of particular interest due to their broad spectrum of biological activities,including anti-virus,anti-cancer,anti-diabetes,anti-inflammatory,and cardiovascular activities.These beneficial properties of isoflavones could be attributed to their antioxidant properties.Daidzein was one of the main components of isoflavones in soybeans and has many pharmacological activities.Hydroxylated of derivatives daidzein are the products of daidzein metabolized by microorganisms or biological in vivo.In structure–activity relationships,the number and positions of hydroxyl groups in the chemical structures have significantly affect the activities of the isoflavones,and increasing the number of hydroxyl groups can increase antioxidant activity.However,hydroxylated of derivatives daidzein are low in natural products and cannot be obtained in large quantities by extraction and separation.At the same time,there were few reports on the structure-activity relationship of the antioxidant activity of hydroxylated of derivatives daidzein.Therefore,a new method for the synthesis of hydroxylated of derivatives daidzein using daidzein or formononetin as raw material was established,and antioxidant activity of the target products PF-1 to PF-7 were evaluated by six antioxidant capacity assays.The effects of hydroxyl position and hydroxyl numbers on the antioxidant activity of hydroxylated of derivatives daidzein were studied,and their structure-activity relationships were clarified.This thesis mainly completed the following works:1.3’,4’,7-trihydroxyisoflavone（PF-1）,4’,7,8-trihydroxyisoflavone（PF-2）and3’,4’,7,8-tetrahydroxyisoflavone（PF-4）were synthesized by methylation,bromination,methoxylation,and demethylation using daidzein as raw material.2.3’,4’,5’,7,8-pentahydroxyisoflavone（PF-6）and 3’,4’,5’,6,7,8-hexahydroxyisoflavone（PF-7）were synthesized by bromination,methylation,methoxylation,and demethylation using daidzein as raw material.3.4’,7,8-trihydroxyisoflavone（PF-2）,4’,6,7,8-tetrahydroxyisoflavone（PF-3）and3’,4’,6,7,8-pentahydroxyisoflavones（PF-5）were synthesized by bromination,methoxylation,and demethylation using formononetin as raw material.4.The obtained intermediates and final products were confirmed by IR,MS,¹H-NMR and ¹³C-NMR,and the structure was consistent with the target compound.The purity of hydroxylated of derivatives daidzein was analyzed by UPLC.All these works provided sample support for antioxidant activity research.5.The antioxidant capacity of compound PF-1 to PF-7 were examined by using six different methods including 1,1-diphenyl-2-picrylhydrazyl radical scavenging,superoxide radical scavenging,nitric oxide radical scavenging,hydroxyl radical scavenging,reducing power assay,and total antioxidant activity.The results showed that:a)Two ortho-diphenol hydroxyl structures of isoflavone made the highest contribution to scavenging DPPH and total antioxidant capacity,and the 7,8-ortho-diphenol hydroxyl structure in the A ring had a greater scavenging effect than the 3’,4’-ortho-diphenol hydroxyl structure in the B ring.b)Two ortho-trisphenol hydroxyl structure had a greater effect on scavenging hydroxyl radicals,and the ortho-trisphenol hydroxyl structure in isoflavone A ring had a greater effect on scavenging hydroxyl radicals than the B ring.c)Two ortho-diphenol hydroxyl structure increased the activity of hydroxyl radicals,however,only one ortho-diphenol hydroxyl structure had little the scavenging effect on the hydroxyl radicals.d)When the isoflavone A ring contained the same ortho-trisphenol hydroxyl structure or ortho-diphenol hydroxyl structure,introduction of hydroxyl group at the 3’or the 5’-position in the B ring could improve the radical scavenging ability on DPPH,NO,and increase the total reduction and total antioxidant activity,but had little effect on scavenging superoxide radicals.e)When the isoflavone B ring contained the same ortho-trisphenol hydroxyl structure,the introduction of at the 6-position in the A ring could improve the radical scavenging ability on DPPH,and increase total reduction activity.f)When the isoflavone B ring contained the same ortho-diphenol hydroxyl structure or ortho-trisphenol hydroxyl structure,introduction of hydroxyl at the 6-position in the A ring,on the contrary,could reduce the radical scavenging ability on superoxide,NO and total reduction activity.g)When there was only a hydroxyl at the 4-position in the B ring,introduction of hydroxyl at the 6-position of the A ring could increase the radical scavenging ability on DPPH,superoxide,nitric oxide,hydroxyl radical scavenging ability,the total reduction and total antioxidant activity.