Investigations Of Anti-inflammatory And Anti-tumor Effects Of Natural Flavones And Their Analogues

It is urgent to study and develop drugs with strong anti-inflammatory and anti-tumor activities,as inflamation and tumor become serious threats to human life and health,and natural products play a crucial role in the development of these drugs.Many plant extracts contain small molecule compounds with strong anti-inflamatory activities,meanwhile78.6 percents of currently approved chemotherapy drugs are associated with natural products.In this reaserch,we investgate the application of natural products with their analogues in anti-inflammatory and anti-tumor.Hydroxylated Flavones are kinds of anti-inflammatory drugs which widely distributed in plants,Although it's anti-inflammatory activity has been reported in many studies,systematic studies on the structure-activity relationship between the anti-inflammatory activity and the structure of hydroxyflavones still been lacking.In the first part of our investigation,we measured the anti-inflammatory activities of 19Hydroxyl-Flavones including fisetin and quercetin in LPS induced mesangial cells,and summary the structure-activity relationship between the anti-inflammatory effects and structures.Experiment results showed that anti-inflammatory effects are related to the number and position of hydroxyl group.In general,Mono-and Di-hydroxylated Flavones exhibited higher anti-inflammatory effect,and the anti-inflammatory of 6-Hydroxylated Flavone is highest.After chemical modification of 6-Hydroxylated Flavone,the anti-inflammatory effect of 6-methoxyflavone,6-acetoxyflavone and flavone 6-sulfate were investigated.6-methoxyflavone exhibited highest anti-inflammatory activity with IC₅₀ at 192 n M.Further mechanism study shows that 6-methoxyflavone down-regulate expression of i NOS protein,inhibit the generation of NO radical,and finally exhibit strong anti-inflamatory effect.dT-QX(Deoxythymidine-quinoxaline conjugate)is a novel anti-tumor small molecule drug synthesized by our research group,it's structure is designed by the combination of two natural products:Hydroxylated Flavones and Celastrol.It can selectively kill tumor cell but show low toxicity in normal cells.Under UVA irradiation dT-QX generate high amount of ROS which enhance the anti-tumor effect of dT-QX.Therefore dT-QX has potential to apply in cancer chemotherapy and photodynamic therapy.In order to study mechanism of dT-QX,optimize its anti-cancer activity,improve chemotherapy efficacy,cancer cell death pathway killed by dT-QX needed to be studied.In the second part of our investigation,three apoptosis inhibitors,one necroptosis inhibitors and three apoptosis activators were administered respectively in combination with dT-QX,and the effect of seven drugs on the dT-QX's anti-tumor activity are evaluated.Results show dT-QX didn't induce cell apoptosis or necroptosis by activating JNK,NF-?B,Caspase or RIPK1 singaling pathway.Different with Hydroxylated Flavones and Celastrol,the mechanism of dT-QX is complicated,but dT-QX indeed exhibit anti-tumor effect by preventing DNA synthesis of tumor cells.The application of DT-QX drugs in the photodynamic therapy of tumors is mainly limited by their low water solubility and the photosensitizer activity which need to be improved.In the third part of our investigation,we study these two aspects.Activity of dT-QX-2Cl(2Cl)lis the highest among all dT-QX analogues.But the bioavailability of2Cl was limited because of low water solubility,so we design a c RGD-targetd nanoliposome to deliver 2Cl.Mc F-7 cells with high expression of integrin?_V?₃on cell surface and Bel7402 with low expression of integrin?_V?₃on cell surface were screened by cell experiments.Targeted modified phospholipids DSPE-PEG-c RGD was successfully synthesized by the reaction of maleimide group on DSPE-PEG-Mal with mercapto group on c RGD,then be used in the preparation of nanoliposome.Cell uptake study and cell cytotoxity study proved that c RGD-targeted drug-delivery nanoliposome(3X c RGD-lipo-2Cl)exhibit strong target effect in MCF-7 cell,and the anti-tumor activity of2Cl was highly enhanced,IC₅₀ of 3X c RGD-lipo-2Cl under the intensity of 3.0 m W/cm²for 20 min of UVA irradiation is only 269.3 n M,less than 50%of free 2Cl.Although pharmacokinetic study show that 2Cl loaded in the c RGD-targeted nanoliposome was rapidly metabolized in mice and could not be used for the direct treatment of tumor,c RGD-targeted nanoliposome still could be used in immunotherapy of tumor.On the other side,Cell cytotoxity study show that under the intensity of 3 m W/cm² for 20 min of UVA irradiation,IC₅₀ of structure-modified drug dT-QX-NAP is only 46.1 n M,the anti-tumor effect is nearly fourteen times higher compared with 2Cl.