Biological Activity Study Of Novel Indole Derivatives As Leukotriene A₄ Hydrolase Inhibitors

Leukotriene A4 hydrolase(LTA4H)is a key enzyme in the inflammatory process of mammals for hydrolyzing leukotriene A4 to leukotriene B4 in arachidonic acid metabolic pathway.Recent studies showed that LTA4H not only played an important role in the development of inflammation,but also closely linked with a variety of malignancies.Indole derivatives exhibit a broad range of biological activities such as anti-tumor,anti-cardiovascular and cerebrovascular diseases and anti-virus.We previously synthesized a series of indole derivatives as novel LTA4H inhibitors according its structure.This paper mainly discussed the effects of these 10 indole derivatives for LTA4H's hydrolyse and aminopeptidase activity.The anticancer activities of these new indole derivatives against human tumor cell lines HT-29 and HeLa were also evaluated by MTT assay in vitro.Firstly,in order to constructed the test platform for screening candidate compounds,expression of(His)6-tagged protein in BL21 and subsequent purification with Ni-affinity chromatography followed by dialysis was performed.Secondly,the inhibitory activities for hydrolyse and aminopeptidase of these derivatives were evaluated.The results show that:the hydrolysis inhibitory activities of HKL 143-1,HKL 135-1 and HKL 160 were 6.15,4.97 and 3.83 ?M respectively.The aminopeptidase inhibitory activities of HKL-A058-23,HKL 135-1,HKL 162 and HKL 160 were 7.08,16.48,11.4 and 20.45 ?M respectively.Finally,we studied whether the LTA4H's inhibitory activities of these compounds would effect to their anti-tumor activity.HT-29(with high expression of endogenous LTA4H)and HeLa(with low expression of endogenous LTA4H)tumor cell lines were selected for anti-tumor activity assay.The results show that:HKL 5-61,HKL 139-1,HKL 2-3-15,HKL135-1,HKL-A058-23 and HKL160 selectly inhibited the proliferation of HT-29 cells,and the IC50 were 0.06,1.41,0.08,0.14,3.97 and 3.19 ?M.The interesting thing is as compared to the high cytotoxic potency for HT-29 cells,HKL 160,HKL 5-61 and HKL-A058-23 showed low cytotoxicity to HeLa cells,which suggested that these compounds might inhibit proliferation of HT-29 cells by regulating the activity of LTA4H.Among them,HKL-160 showed no effect for HeLa cells's proliferation.These results indicate that HKL 160 exhibits good inhibitory activity of LTA4H and good proliferation inhibitory activity of HT-29 cells.Further chemo-biological study of HKL-160 with regards to its antitumor pathway as well as its enzymatic targets and in vivo investigation are ongoing in this laboratory.