Synthesis Of Nitric Oxide Synthase Inhibitors And Nitric Oxide Scavenger And Their Protective Effects Against Radiation

Objective:Ionizing radiation is a non-specific physical stimulating factor.When it acts on the body,it induces the ionization of molecules,production of free radicals,breakage of chemical bonds,and eventually leads to various damages of the body.At the same time,it activates NF-?B and causes upregulation of iNOS expression,which leads to the overproduction of NO.Excessive NO mediates severe cytotoxic effects that can lead to cell death and cause many pathological conditions.iNOS inhibitors or NO scavengers can reduce iNOS-mediated overproduction of NO in pathological conditions without affecting or minimally affecting NO levels in normal tissues.So they have always been a potential treatment for some diseases.In this experiment,two NOS inhibitors(2-ADT?2-AADT)and NO scavenger(Fe(DETC)2)were synthesized,and their radioprotection effects were systematically evaluated through pharmacological experiments,and potential mechanism was preliminary explored.Methods:This study mainly includes two parts:1.the synthesis and activity evaluation of NOS inhibitors;2.assessment of radiation protection effects of NO scavengers.In the synthesis part,3-bromopropylamine hydrobromide and thiourea were used as starting materials to obtain the target compounds through cyclization and acylation.In the pharmacological experiment part,the 30-day survival test was used to evaluate the overall protective effect of the compounds on mice;the protection of hematopoiesis and immune system under single sublethal dose irradiation was investigated by measuring peripheral blood parameters,CFU-S,and BMNC.By measuring the NOx content in mouse plasma at diferent times,the effect of compounds on NO content was evaluated;the effects of compounds on the antioxidant system were evaluated by investigating the changes of T-SOD,CAT,GSH,and MDA in liver and lung tissues on the 7th day after irradiation with 6.0 Gy.The protective effect of compound on DNA was detected by the mouse peripheral blood comet assay.HE staining and immunohistochemical assay were used to determine the protective effect of the compound on mouse small intestine injury and the effect of key protein expression.Results:2-ADT and 2-AADT significantly prolonged the average survival time of ICR mice irradiated with 7.5 Gy y-rays;and can increase the number of WBC,PLT,BMNC,bone marrow DNA content,CFU-S and organ index of irradiated mice in varying degrees;they also increased the activity of SOD and CAT,increased GSH content and decreased the content of MDA in liver and lung tissues of mice post irradiation;and they can reduce the NOx content in plasma at different times.Comet experiments indicated that the compounds can effectively reduce DNA strand breaks.HE staining and immunohistochemistry indicated that the compound could reduce the villus-crypt structure damage of the small intestine and promote the proliferation of vill+intestinal cells,Paneth cells and Ki67+cells and lower the expression of nitrotyrosine in irradiated mice;and they can increase the immune organ index.Treatment with the NO scavenger Fe(DETC)2 also increased the 30-day survival of mice and increased the number of WBC,CFU-S,bone marrow DNA content and organ index.Conclusion:NO synthase inhibitors and nitric oxide scavenger have a good protective effect on radiation-injured mice.The radioprotective actions of 2-ADT and 2-AADT on hematopoietic and intestinal injury in mice are achieved via accelerating hematopoietic system recovery,reducing damage to immune organs,decreasing oxidative and nitrosative stress by enhancing the antioxidant defense system and reducing NO as well as ONOO-content,and mitigating the radiation-induced DNA damage.Fe(DETC)2 can also protect hematopoietic and immune system by stimulating hematopoietic recovery and protection of immune organs.