Study On The Preparation,Antioxidant And Antityrosinase Activities Of Flavonoid Derivatives

There are abundant flavonoids in plants that are both medicinal and edible.For example,Ampelopsis grossedentata contains a large amount of dihydromyricetin,Myrica rubra contains a lot of myricetin,Citrus maxima contains naringenin.They have a variety of biological activities,including antioxidant activity,antityrosinase activity and so on.The structures of dihydromyricetin,myricetin and naringenin contain some easily reactive functional groups,which can participate in specific chemical reactions to prepare some flavonoids derivatives.Compared with dihydromyricetin,myricetin and naringenin,some physical and chemical properties of their derivatives will change.In this paper,we take dihydromyricetin,myricetin,naringenin and other flavonoids as the research object to explore the possible chemical reactions,and the changes of antioxidant activity and antityrosinase activity of the produced products after reaction.Considering that the structures of dihydromyricetin,myricetin,naringenin are unstable,as well as there are many easy reaction sites,making it difficult to prepare their derivatives.Therefore,some simplified structural mother nuclei are selected,including 4-chromanone,chromone-2-formic acid,chromone-3-formic acid and chromone-3-formaldehyde.They only have the most basic chromone structure,and then explore the possible chemical reactions of these chromones as well as the biological activity of their derivatives.The main contents are as follows:（1）Taking dihydromyricetin,myricetin and naringenin as raw materials,a series of flavonoids derivatives were synthesized by Mannich reaction.The progress of the reaction and the purity of the product were analyzed on polyamide film,and the antioxidant activity of the product was tested.Unfortunately,their ABTS radical scavenging rate and DPPH radical scavenging rate were lower than that of dihydromyricetin,myricetin and naringenin.The scavenging activity of only a few derivatives was close to that of the parent nucleus.（2）In order to verify the effect of the glycosylation of flavonoid aglycones on their antityrosinase activity,the inhibitory activities of dihydromyricetin,myricetin,naringenin and myricitrin on tyrosinase diphenolase were compared.The results showed that the inhibitory activity of myricitrin on tyrosinase diphenolase decreased significantly after the glycosylation of myricetin.（3）Using 4-chromanone as raw material,the three-component reaction between4-chromanone,aldehyde and malononitrile was explored.A benzo[c]chromene derivative was successfully prepared,and its reaction conditions were optimized by one-factor optimization.Under the optimal reaction conditions,14 kinds of benzo[c]chromene derivatives were synthesized,and their inhibitory activities against tyrosinase diphenolase were evaluated.（4）Some other chromone derivatives were synthesized from chromone-2-formic acid,chromone-3-formic acid and chromone-3-formaldehyde,and their scavenging rates for ABTS radical and DPPH radical were tested.