| Flu is caused by different subtypes of influenza virus which can lead to severe diseases of acute viral upper respiratory infection.Additionally,flu has the nature of fast spreading,short latency,high morbidity and strong infectiousness.So far,the treatment of flu depends on amantadines,neuramidinase(NA)inhibitors and vaccination.However,the treatment of flu is facing challenge:severe daug resistance to amantadines;emerging drug resistance to NA inhibitors;low efficiency of vaccination for people with low immunity.Triazavirin is non-nucleoside broad-spectrum antiviral drug developed by Ural Federal University based on 20 years’ fundamental research,which has come into the market in 2015 in Russian.Triazavirin showed good anti-flu activities both in vivo and in including amantadine-resistant strains.However,the pharmacological mechanism of triazavirin has not been cleared,maybe inhibiting the entry of virus to host cells.So we put effort to study on the synthetic process of triazavirin due to its anti-flu activity and optimize the synthetic process,which has great significance to industrial production and is conducive to the treatments of people infected with influenza virus in our country.We analyzed the key factors in the synthetic process of triazavirin based on the original patents and the reaction mechanism,and optimized these factors in order to gain high yield at a low cost.Firstly,we determined six factors which can greatly influence the synthetic process.Then,we set five levels for each factor and designed orthogonal experiment to determine the optimal reaction conditions.Finally,we gain the optimal reaction conditions and yield increased from 74%to 83.7%。Three batches were conducted and the yields were stable,and the purity of the product which was determined by HPLC is more than 99.9%,conforming to the standard of Chinese Pharmacopeias.So,we provide a safe,reliable and cheap way to prepare triazavirin.On the other hand,this paper describes modifications of C2 and C6 of the triazolotriazine moiety of TZV which can be easily metabolized.In addition,we designed some novel triazolotriazines nucleosides(nucleotides)based on the structural similarity between triazolotriazine and natural purine bases.In the design of target compounds,we combined the ribose moieties of U.S.FDA approved anti-HBV nucleoside analogue adefovir and broad-spectrum antiviral ribavirin with triazolotriazines bases.Considering that we introduced glycosyl groups of adefovir and ribavirin to our newly designed triazolotriazines nucleoside analogues and other novel nucleoside analogues designed by us have anti-HBV avtivities,we not only tested their anti-influenza activity but also anti-HBV DNA replication activity.In the influenza virus-yield reduction assay,acyclic nucleoside LT4a2 showed activities against H5N2,H5N6 and H5N8 strains(IC50=81.88μM,184.91μM and 194.65μM,respectively).Compound LTBr displayed potent avtivities against H5N2(IC50=15.40μM)and H5N6(IC50=15.99μM),comparative to the reference drug ribavirin(ICs0=11.14μM for H5N2,IC50=14.15μM for H5N6).Nucleoside analogue LTH2c showed potent inhibitory activitiy against H5N2(IC50=11.54μM)and H5N6(IC50=14.15μM),similar to ribavirin and better than triazavirin.In the anti-HBV DNA replication assays,LTHlc,LT4al and LTH2b showed modest inhibitory activities of DNA replication,ranging from 35.69%to 43.55%,and all of the test compounds showed no toxicity excepted for LT4c2,LTH2a and LTH2c.Although no designed compounds showed inhibitory activities more the lamivudine,the result revealed that triazolotriazines nucleosides(nucleotides)had modest anti-HBV activities and need to be further investigated.In conclusion,this paper described the synthesis process optimization of triazavirin and provided a method with high yield and low costs.In addition,some novel triazolotriazines nucleosides(nucleotides)were designed,synthesized and evaluated their antiviral activities. |
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