Nucleoside acyclic

Nucleoside Acyclic Phosphates. 2-Chloro-2,A-dioxo-3-methyltetrahydro-... 

Nucleoside Acyclic Phosphates. - 2.1.1 Mononucleoside Phosphate Derivatives. A preliminary study on a novel solid phase reagent (Scheme 1) for the capture phosphorylation of nucleosides has been described. The 1 % cross-linked divinylbenzene-polystyrene copolymer, containing cyanoethoxy iV,AT-diisop-ropyl phosphine was used for the selective phosphorylation of uridine to 5 -uridine monophosphate (UMP) in 67% yield. ... 

Nucleoside Acyclic Phosphates - It is well established that most nucleoside analogues become biologically active as a result of cellular conversion to phosphomonoesters. For this reason there has been increasing interest in the synthesis of nucleoside phosphotriesters and in some cases, i osphodiesters which might act as membrane soluble pro-drugs of the bioactive nucleotides. The diethyl-, dipropyl- and dibutyl-phosphates (1) of 2, 3 -dideoxy-3-deaza-adenosine have been synthesis and shown to possess anti-HIV-1 activity at non-cytotoxic doses. Phosphate triester derivatives of the anti-leukaemic nucleoside nmbi/io-cytidine have... 

The cyclization of the 2-hydrazino-4-methylquinohne derivatives of sugars 740 by the action of ferric chloride to give the acyclic nucleosides 741 (94MI295) (Scheme 128). 

Recently, Charette et al. have also demonstrated this behavior in the stereoselective cyciopropanations of a number of enantiopure acyclic allylic ethers [47]. The high degree of acyclic stereocontrol in the Simmons-Smith cyclopropanation has been extended to synthesis several times, most notably in the synthesis of small biomolecules. Schollkopf et al. utilized this method in their syntheses of cyclopropane-containing amino acids [48 a, b]. The synthesis of a cyclopropane-containing nucleoside was also preformed using acyclic stereocontrol [48c]. 

However, acyclic nucleotide analogs (acyclic nucleoside phosphonates) have been developed, which carry one phosphonate moiety and require only the two subsequent phosphorylation steps (De Clercq et al. 1978). Independent of virus-encoded kinases, they display a broader spectrum of efficacy. This class comprises important drugs against HIV (tenofovir) and HBV (adefovir, tenofovir), as well as cidofovir, which is approved for use against CMV retinitis, but also displays an exceptionally broad efficacy profile against many herpesviruses, adenovirus, poxviruses, and papillomaviruses (De Clercq and Holy 2005). 

De Clercq E, Descamps J, De Somer P, Holy A (1978) (S)-9-(2,3-Dihydroxypropyl)adenine an ahphatic nucleoside analog with broad-spectrum antiviral activity. Science 5 563-565 De Clercq E, Holy, A (2005) Acyclic nucleoside phosphonates a key class of antiviral drugs. Nature reviews 4 928-940... 

TACV Triacyclic analogue of acyclovir TGCV Triacyclic analogue of ganciclovir ANP Acyclic nucleoside phosphonate TK Thymidine kinase... 

Fig. 1 Stractural formulae of acyclic nucleoside analogues (anti-herpesvirus agents)...

The acyclic nucleoside phosphonates (ANPs) can be considered as nucleotide rather than nucleoside analogues, in that, besides the purine or pyrimidine base, they contain an (acyclic) sugar moiety to which a phosphonate is attached. In these nucleotide analogues (Fig. 2), the phosphoric ester grouping (= P-O---C-----) is... 

The prototype member of the ANPs is (5)-9-(3-hydroxy-2-phosphonyl-methoxypropyl)adenine (HPMPA) (Fig. 2), first described for its broad-spectrum anti-DNA virus activity in 1986 (De Clercq et al. 1986). Then followed by the description of various other acyclic nucleoside phosphonates in 1987 (De Clercq et al. 1987). At present three acyclic nucleoside phosphonates have been licensed for clinical use cidofovir, adefovir, and tenofovir (Fig. 2). 

Appropriately designed prodrugs, for example, phosphonoamidates (Lee et al. 2005), may allow acyclic nucleoside phosphonates such as tenofovir to be specifically targeted at tissues, that is, lymphatic tissue, where the virus (i.e., HIV) replicates. This principle has been recently extended to another nucleotide analogue, GS-9148 (Cmiar et al. 2008) and its phosphonoamidate prodrug, GS-9131 (Ray et al. 2008). 

All NRTIs, as exemplified for AZT (Fig. 7), act in a similar fashion following their uptake by the cells, they are phosphorylated successively to their 5 -monophosphate, 5 -diphosphate, and 5 -triphosphate form (De Clercq 2002). Unlike the first phosphorylation step in the metabolic pathway of the acyclic guanosine analogues (see above), which is carried out by a virus-encoded enzyme (thymidine kinase), the first as well as the subsequent phosphorylations of the 2, 3 -dideoxynucleosides are carried out by cellular enzymes, that is, a 2 -deoxynucleoside (e.g., dThd) kinase, a 2 -deoxynucleotide (e.g., dTMP) kinase, and a (2 -deoxy)nucleoside 5 -diphosphate (NDP) kinase. 

De Clercq E, Holy A (2005) Acyclic nucleoside phoshonates a key class of antiviral drugs. Nat Rev Drug Discov 4 928-940... 

Wyles DL, Schooley RT, Kaihara KA, Beadle JR, Hostetler KY (2008) Anti-hepatitis C virus repli-con activity of alkoxyalkyl esters of (S)-HPMPA and other acyclic nucleoside phosphonates. In Abstracts of the 21st international conference on antiviral research, Montreal, QC, Canada, 13-17 April 2008. Antiviral Res 78 A21, no 15... 

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