Study On Coumarins As Antioxidants And BRD4 Inhibitors

Coumarins are benzopyrone compounds that have outstanding antioxidant,anticoagulant,antibacterial,anti-inflammatory,antitumor,antiviral,enzyme inhibitory activities etc..Antioxidant and anti-tumor activity had been widely used in pharmaceutical chemistry.This work designed and synthesized novel coumarin antioxidants and BRD4 inhibitors utilized coumarin that have good biological activity as research object,to study the anti-oxidation and antioxidant properties of compounds.1.Antioxidative activities of conjugates of coumarin and hydroxytyrosol:The body will undergo peroxidation to produce oxidative stress,and cause the accumulation of reactive oxygen species（ROS）,reactive nitrogen（RNS）and other free radicals for diseases.Antioxidants also can play a synergistic effect in inhibiting tumors.Hydroxytyrosol,a polyphenol antioxidant,has important applications in anti-oxidation,anti-inflammatory and anti-cancer researches.A series of C-6,-7 or-8positions substituted hydroxytyrosol-coumarin esters were designed and synthesized in principle of conjunction,and their free radical scavenging activity,toxicity and anti-oxidant mechanism were studied.Sepecially,the intermediate3,4-dibenzyloxyphenethyl alcohol was obtained through esterification,substitution and reduction reactions from 3,4-dihydroxyphenylacetic acid.Following,it reacted with C-6,7 and 8 positions different substituted 3-carboxycoumarins by esterification reaction and hydroxyl protecting group was removed to obtain 20 target compounds.DPPH and ABTS⁺free radical scavenging assays revealed that all compounds showed higher free radical scavenging activity than dibutyl hydroxytoluene（BHT）,hydroxytyrosol and coumarin.SAR study showed that the hydroxyl groups at the C-6,7,and 8 positions and their number are essential for maintaining antioxidant activity.Toxicity assays found that compound 72q has lower hemolytic toxicity than BHT,and had weaker anti-proliferative effect on normal WI-38 and GES cells.In the H₂O₂-induced Hep G2 cell oxidative stress model,compound 72q enhanced viability of Hep G2 cells and reduced cell apoptosis;reduced the production of ROS and the release of LDH in oxidative stressed cells,and increased the levels of GSH and SOD in cells.In addition,compound 72q showd better stability than hydroxytyrosol.It can be seen that the target compound 72q is an antioxidant with high efficiency and low toxicity.The results provided a new idea for the development of new antioxidants.2.Studies on novel coumarin as BRD4 inhibitors:Bromodomain protein 4（BRD4）is a chromatin binding protein,and its overexpression in cells is closely related to cancer,inflammation and other diseases.In this chapter,a series of new C-6substituted coumarin compounds were designed and synthesized through hybrid strategy based on the BRD4 inhibitor ABBV-075 determined their BRD4 enzyme inhibitory activity.6-Br-2-hydroxyacetophenone was used as original material to synthesize 6-Br-4-methoxycoumarin by Knaowenger reaction and substitution halogenation.They were combined with 2,5-substituted phenylboronic acid through Suzuki reaction to obtain 25 compounds.The BRD4（BD1）enzyme activity showed that the target compounds 110a–n had obvious enzyme inhibitory effects,especially the compounds 110b,110c,110e–g,110j and 110k,which have acceptable IC₅₀,less than 200 n M.According to the discussion of the anti-proliferative activity of the compound on tumor cells,it is concluded that the compound 110c has a relatively prominent solid tumor inhibitory activity.The molecular simulation docking showed that the C-6 position of the compound 110c replaces the ethanesulfonamide group at the m-benzene extending into the ZA of the BRD4 protein.After that,the compound110c,which has good enzyme activity and cell activity,was selected for modification to obtain compounds 111a–k.They showed better BRD4（BD1）enzyme inhibitory activity,and show better than BRD4 inhibitors,such as JQ-1,PFI-1 and ABBV-075,and especially to solid tumor inhibitory activity.Compounds 111d,111e and111k are very likely to become a good hit compound and provide a reference for drug design.This research provides an important research basis for the development of new BRD4inhibitors.In summary,this work has designed and synthesized two types of coumarin compounds,which have achieved good results in anti-oxidation and anti-tumor activities,indicated that coumarin as a skeleton is an important research idea in drug development.It used the advantages of natural products and good foundation for the development of good compounds,and also provided a development strategy for coumarin drugs.