Synthesis And Antiviral Activity Of Novel Substituted Acyclic Nucleotide Analogs Derived From 8-Azapurines

Chronic hepatitis B,infected by hepatitis B virus,is a kind of chronic,developmenttal and mortal disease.It is prevalent in our country.To date,lamivudine,which is a kind of nucleotide analogues,are the lead antiviral agents for chronic HBV treatment,however,it has been shown to seriously drug resistance and hepatotoxicity.Recently 9-[2-(phosphonomethoxy)ethyl]purine derivatives,belongs to acyclic nucleoside phosphonates(ANPs),have been gotten the broad concern for their good antiviral activities,low resistance profile,higher efficient and controllable toxicity.Adefovir dipivoxil is in the case of adenine derivative of acyclic nucleoside phosphonates(ANPs),its potent antiviral activities and security have been recognized during the preclinical and clinical test.In 2002,USA FDA authorized Adefovir Dipivoxil(ADF) to cure chronic hepatitis B.His chemical structure is characterized by several structural parameters,i.e adenine as the base,acyclic nucleoside phosphonomethyl ethers as the sede chain,phosphoric acid,and dipivoxil ester,and so on.The Clinical datas show that adefovir dipivoxil can better suppress the replication of HBV DNA,and it has lower rate of drug resistance.It's significant merit is strongly inhibit the YMDD mutations variant in patients therapied by Lamivudine.It is long-term advantage of continuing ADF therapy in patients,and it can significantly cut down the level of cccDNA.It hasn't correlate report that the therapeutic dose of ADF,10 mg/d,may induce side effect.However it has shown that ADF can causes nephrotoxicity by using higher doses,and it also shown that ADF generates pivalic acid,formaldehyde during the release of free PMEA in vivo by enzymic hydrolysis.Pivalic acid may decrease carnitine levels in humen blood serum at high doses,and the generation of toxic formaldehyde may not be of concern at the therapeutic doses.After we summarized the SAR of ANPs,and according to the theory of bioisostere,by using adefovir as lead compound,we design three kind of novel chemical molecule structure through replace the 6-amino group by hydrosulfuryl substitute or aminoderivative, simultaneously replace the C8 by N,and retain phosphate acid or introduce bitrifluorethyl ester and ethyl ester.We have designed three approaches to prepare 19 novel target compounds.At first we use PCl₃ as the raw material,tried to get the target compounds throught the four reactions as esterification,hydroxymethylation,sulfonication,alkylation.This route failed to aford the target compounds,because we coundn't get the desired intermediate throught analyzing IR data.Thus we design the second route based on the first route.We use the 4,6-dichloropyrimidin-5-amine and PCl₃ as raw materials,try to synthesised target compounds throught alkylation,diazotization,hydroxymethylation,halogenation, esterification.Initially,we tried the first approach to introduce bitrifluorethyl ester,we got new structures which moiety of phosphate acid ester has been exchanged by chance.These new molecules have been identified by analyzing ¹H-NMR,MS,IR data,and they are firstly reported.Antiviral activity test was carried out with HepG2 2.2.15 cell strain clone and transfection by HBV DNA in vitro.The positive control is Lamividine.The test results show the inhibitory rate of new compound 3-9 on HBsAg is correspond with Lamifudine and inhibitory rate on HBeAg is higher than Lamifudine at 100μg/ml.It is noted that the compound 3-9 show nontoxic to cell at 100μg/ml,otherwise Adefovir dipivoxil show cell toxicity at 50μg/m.So the new structure is hopefully protected by apply for patent in the futrue.Base on our design,6-thio-8-aza-purine is the primary framework.So we design the third route,respectively use the 4,6-dichloropyrimidin-5-amine and diethyl phosphonate as raw materials,and synthesis 16 new compounds throught alkylation,diazotization, hydroxymethylation and so on.Now the biological activity assess of target compounds is under taking.