Cytosine nucleoside

C]-FlAC was synthesized from [2- C]cytosine in the general manner used for unlabeled 748 (FIAC), and its metabolic fate in mice was studied. The compound (after i.v. injection) was deaminated by cytosine nucleoside deaminase and appeared as [2- C]-FIAU in plasma, as confirmed by experiments on rats having a very low level of the deaminase, and by treatment with tetrahydrouridine, a nucleoside deaminase inhibitor. This was further confirmed by the use of purified human deoxycytidine deaminase. It was... 

Stone, K., Uzieblo, A. and Marnett, L.J. (1990b). Studies of the reaction of malondialdehyde with cytosine nucleosides. Chem. Res. Tox. 3, 467-472. 

Lamivudine (Epivir-HBV) is an oral synthetic cytosine nucleoside analogue having antiviral effects against HIV and hepatitis B virus. In patients with chronic hepatitis B, lamivudine is effective in suppressing hepatitis B viral replication, normalizing... 

Schinazi RF, Lloyd RM Jr, Nguyen M-H, Cannon DL, McMillan A, Ilksoy N, Chu CK, Liotta DC, Bazmi HZ, Mellors JW. Characterization of human immunodeficiency viruses resistant to oxathiolane-cytosine nucleosides. Antimicrob Agents Chemother 1993 37 875-881. 

Lamivudine (3TC, Epivir) is a cytosine nucleoside analogue with activity against HIV-1, HIV-2, and hepatitis B virus. It is approved as part of a multidrug regimen for the therapy of HIV infection in adults and children and has been used for HIV postexposure prophylaxis. Combination products contain lamivudine with either zidovudine (Combivir) or zidovudine and abacavir (Trizivir). The use of low-dose lamivudine in the treatment of chronic hepatitis B is described in Chapter 50. 

C) Lamivudine is a cytosine nucleoside analogue efavirenz is an adenosine nucleotide analogue. 

Elvucitabine is an L-cytosine nucleoside in phase III development for treatment of HIV and HBV infections (Figure 8.6). Its antiviral activity has been shown to result... 

Cytosine reacts similarly, as do both uracil and cytosine nucleoside derivatives such as 83 and 85 which gave their respective 5-hydroxymethyl derivatives 84 and 86 in 95% yield <2002SL2043>. 

The syntheses of both l-(3-deoxy-/ -D-g/i/cm>-pentofuranosyl-2-ulose)uracil (25c) and l-(3-deoxy-/ -D-g/ /cm>-pentofuranosyl-2-ulose)cytosine (30b) by selective elimination reactions have been reported.4,5 Thus, the reaction of sulfonyl derivatives of the cytosine nucleoside 26, and uracil nucleosides 23a, 23c, and 28, with sodium benzoate in N,N-dimethylformamide (DMF) leads to 3 -deoxy-2 -ke-tonucleosides by way of such (presumed) unsaturated intermediates as 24a, 24c, 29a, and 29b. However, in one instance, the intermediate... 

The borohydride reduction of 2 - and 3 -ketocytidine derivatives having or lacking an N4-acetyl group provided a facile route to cytosine nucleosides labeled with tritium at specific positions of the sugar.28 Reduction of either 20a or 20c with sodium borohydride in ethanol-benzene afforded the arabino and the ribo derivatives in the ratio of 4 1. Treatment of the reduction mixture with methanolic ammonium hydroxide gave the deacetylation products, 82b and 19b, isolated in crystalline form by preparative, thin-layer chromatography. 

All figures presented for cytosines are unpublished data measured by I. Kulakowska and K. L. Wierzchowski, and those for cytosine nucleosides by I. Kulakowska and A. Rabczenko (Institute of Biochemistry and Biophysics, Polish Academy of Science, Warsaw). b Uncertain value. 

By similar reasoning, the position of the sugar in cytosine nucleosides and deoxy-... 

Cytidine and related pyrimidine nucleosides have also been synthesized by the mercuri procedure.198 In the case of the cytosine nucleoside, prior blocking of the amino function is necessary, in order to obtain a mercury derivative [(-V-acetylcytosine)mercury] adaptable for nucleoside synthesis. Reaction of one mole of LV with two moles199 of tri-O-benzoyl-D-ribofuran-... 

Six novel, cytosine nucleosides were isolated from the fermentation broth of S. griseochromogenes, which produces blasticidin S (55, see Scheme 22). The structural relationship between these nucleosides and cytosinine, the nucleoside moiety of blasticidin S, was investigated.87 One of these compounds was identified as l-(/3-D-glucopyrano-syluronic acid)cytosine (53). The presence of 53 was taken as evidence... 

Powner MW, Anastasi C, Crowe MA, Parkes AL, Raftery J, Sutherland ID. On the prebiotic synthesis of ribonucleotides photoanomerisation of cytosine nucleosides and nucleotides re- 94. visited. ChemBioChem. 2007 8 1170-1179. 

Emtricitabine is a cytosine nucleoside with antiviral potency towards HBV and HIV. It is only slightly different from lamivu-dine. After 48 weeks of treatment (200 mg/day), it was possible to achieve HBV-DNA negativity in 60% and HBeAg negativity in 50% of cases. Tolerance is good (N. Leung et af, 2001). 

This new sugar had the formula C5Hio04- In other words, it possesses one atom of oxygen less than does a pentose. Analysis of its benzyl-phenylhydrazone, of its guanine and hypoxanthine nucleosides, and of its thymine and cytosine nucleosides, confirmed this composition. It therefore appeared probable that the sugar might be a desoxypentose. 

The PD and LD spectra of adenine and cytosine nucleosides have been recorded by a German group both in the negative and positive ion modes. Since the former technique shows only a [BH] ion in the positive mode, several lower-mass fragments become important for interpretation in the negative ion spectra, particularly the elimination of NH4. An intense [B-H]- ion is also present in both the PD and the LD negative-ion spectra. 

A study of the fragmentation pattern of deuterium and oxygen-18 labeled derivatives of cytosine nucleosides established that a major fragmentation process occurred that was absent in the spectra of other nucleosides. The various fragmentation pathways for prostaglandins A, B, E, and F were de-termined by the use of specific derivitization with d -tetramethylsilane. 

The degradation of hexopyranosyl cytosine nucleosides in buffers of acid, neutral and alkaline pH has been followed by HPLC. The compounds were found to degrade by hydrolysis to cytosine and/or deamination to the corresponding uracil nucleosides. ... 

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