The Study Of Inhibitory Effects Of Furoxan Derivatives On SjTGR Activity And Their Killing Activities Against Schistosoma Japonicum

Schistosomiasis,is a widespread and hazardous zoonotic parasitic disease caused by schistosome,which can infect human and other mammals.It is one of the six major tropical diseases defined by the World Health Organization(WHO),and it is also one of the most easily neglected tropical diseases,affecting public health security in developing countries.Up to 2016,schistosomiasis is distributed in 78 countries or regions according the statistical data of WHO and at least 206.4 million people need preventive treatment.Schistosomiasis japonica is mainly caused by Schistosoma japonicum in China,which affects the health of people in epidemic areas seriously and the development of animal husbandry.It is also one of the major public health problems in China.At present,praziquantel(PZQ)is the first choice for treatment of schistosomiasis.Because of its low cost,convenient use,low toxicity and ability to inhibit all species of schistosomes,it is currently the only widely applied chemotherapy drug for the schistosomiasis.Since PZQ was successfully synthesized in the 1980s,it has been used to control and treat schistosomiasis for more than 40 years.Many studies showed that PZQ mainly acted on adult schistosomes,but had poor efficacy on schistosomula.PZQ could not resolve the problem of repeated infection and long-term repeated uses of it may lead to the emergence of resistant strains of schistosomes.Some studies had found that the artemisinin has a certain inhibiting action against schistosomula,but the treatment effect on adult worms of schistosomes is not good.Moreover,the wide use of artemisinin drugs would cause troubles for the treatment of malaria,which restrict the treatment for schistosomiasis by artemisinin drugs.Therefore,it is urgent to develop novel and effective anti-schistosomiasis compounds.Most eukaryotes could eliminate exogenous and endogenous reactive oxygen species(ROS)by thioredoxin reductase(TrxR)and glutathione reductase(GR)to achieve detoxification.Schistosome living in the veins of their hosts need resist ROS produced by host immune system and their metabolism to maintain normal vital activities.Studies had revealed that schistosome is lack of catalase and does not possess separate TrxR or GR,but thioredoxin glutathione reductase(TGR)of schistosome is a multifunctional enzyme containing selenium with the activities of TrxR,GR and glutathione reductase(Grx),which is essential to maintain the redox balance in schistosome.Several studies showed that the compound named Furoxan could inhibit the TGR activity of Schistosoma mansoni and kill all development stages of S.mansoni,and it may be a potential leading compound of anti-schistosomiasis drugs.In this study,39 Furoxan derivatives were used to assess the inhibitory effect against the TrxR activity of recombinant TGR of Schistosoma japonicum(rSjTGR)and wide type TGR in soluble worm antigens of S.japonicum(wtSjTGR).The compounds with good inhibitory effect against the TrxR activity of rSjTGR and wtSjTGR were screened.Then LGM-35 was chosen and its effects against S.japonicum were evaluated in vitro and in vivo.The main contents are concluded as follows:1.Inhibitory effects of Furoxan derivatives on the TrxR activity of rSjTGR and wtSjTGRAccording to the inhibitory effects of Furoxan derivatives against the TrxR activity of rSjTGR and wtSjTGR,the corresponding half inhibitory concentration(IC50 value)of each derivative was calculated.The compounds with good inhibitory effect against the TrxR activity of rSjTGR and wtSjTGR were picked out.The results showed that seven Furoxan derivatives have better inhibitory effect against the TrxR activity of rSjTGR and wtSjTGR compared with the lead compound Furoxan.The half maximal inhibitory concentration(IC50)values of LGM-2 and LGM-35 were nanomolar level especially.2.Inhibitory effects of LGM-35 on the worms of S.japonicum in vitroThe 14-day-old,28-day-old and 35-day-old worms of S.japonicum were cultured in RPMI 1640 medium for 2 h,respectively.Different concentrations of the compound solutions were added and the survival situation of the schistosomes were observed at different times.The results showed that LGM-35 had a certain killing effect on S.japonicum.Observation of the cultured worms showed that wrinkles atrophied and vesicles on the body surface of S.japonicum increased after treatment with LGM-35(50μM)compared with the blank control group.3.Inhibitory effects of LGM-35 on 14-day,28-day and 35-day old worms of S.japonicum in vivoThe mice were injected intraperitoneally with 20mg/kg LGM-35 solution once a day for five consecutive injections at 14-day,28-day and 35-day post-infection,respectively.Then,mice were sacrificed at 42-day post-infection.The results showed that the worm reduction rates of mice injected with LGM-35 solution at the three different periods were 2.43%(P>0.05),28.49%(P>0.05)and 1.29%(P>0.05)compared with control group,respectively.