Design,Synthesis,Electrochemical Behavior On Charcoal Electrode,and Activity Evaluation Of O-nitro-aroylated Fluorouracils As Antitumor Agents

Conjugation with deoxynucleotide of 5-Fluorouracil(5-Fu)and 5-Fu derivatives competiting uracil lead to binding with thymidine synthase,resulting in the lethal synthesis of thymidine nucleotides,and interfering DNA synthesis,which inhibit proliferation of tumor cell.However,the severe toxicity of 5-Fu and its derivatives from the lack of the selectivity to tumor cell limits clinical application.The condensates of position 1 in 5-Fu and o-aromatic acids such as 3-methyl-3-(2-nitrophenyl)butanoic acid and 2-(2-nitrophenoxy)acetic acid designed based on the much higher activity of amidohydrolase and reductase and the lower PH value in tumor cell than in normal cell were expected to be the potent anticancer agents highly selective to tumor cell in light of hydrolysis of the amide bond in position 1 regulated by the electronic or steric characteristics.Optimization of acylation reaction such as solvent,catalysts reaction time,and reactant ratio gave the yield more than 60%,which all target compounds were confirmed.The electrochemical behaviors of target compounds in the different concentrations such as the value and the shape of peak current,and the linear relationship between the peak current value and the square root of scanning speed on the reductase-modified electrode and on the bare electrode in the different PH value PBS to in vitro mimic the physiological environment were determined by cyclic voltammetry.It resulted in that the optimum condition of target compounds was 7.2 PH value,100mv/s of scanning rate,0.1MKCl,and 4mM/L concentration.The peak current value on the optimum condition was accordance with b2>b6>b5>bl>b3.The experiments also showed that the variation of peak current value of target compounds was large with the variation of the PH value,in which the peak current value of b2 was minimum at PH value 7,namely the worst oxydating ability of nitro group,but the high value of peak current at PH value whether more than or less than 7.And the peak values of b2,b5,and b6 higher than the ones of the other target compounds at the same PH value suggested that they possessed the potent cyclization.Lactamidation reaction rate of target compounds detected by spectrophotometric method and Matlab language studies was in accordance with the result of cyclic voltammetry.This suggested that the electron-withdrawing effect of the side chain of target compounds was parallel with the reduction degree of nitro group.So the reduction degree of nitro group,the electron-withdrawing effect of the side chain,and the spatial conformation is directly related to the release of 2H-benzo[b][1,4]oxazin-3(4H)-one and 5-Fu from the target compounds.Moreover,MTT test indicated that the target compounds(IC50<6.06μM)behaved proliferation inhibition in K562,Hela,and A549 cell lines,in which the in vitro proliferation inhibition in cancer cell of b2,b5,and b6 were significantly more than the one of the positive control 5-Fu,and their IC50 was above one time lower than the one of 5-Fu.