Synthesis and antiviral and cytotoxic activity of iodohydrin and iodomethoxy derivatives of 5-vinyl-2'-deoxyuridines, 2'-fluoro-2'-deoxyuridine, and uridine

5-Substituted-2′-deoxyuridines as anti-HSV-1 Agents: Synthesis and Structure Activity Relationship

Nucleoside and pyrophosphate analogues are currently in use to treat infection with Human herpesvirus 1 (HSV-1). Both series of compounds exert their activity by inhibition of the viral DNA polymerase either directly, or after anabolic phosphorylation. As the X-ray structure of the viral-specific DNA polymerase is not known, it is difficult to design a nucleoside or non-nucleoside antiviral agent which specifically inhibits this enzyme. Therefore, alternative strategies have relied on extensive structure activity relationship studies of anti-HSV-1 agents in an endeavour to understand the essential structural requirements for activity and hence the design of drugs with increased selectivity. A virus-specific enzyme which plays a crucial role in the selective activation of nucleoside analogues is thymidine kinase. Present knowledge regarding the specificity of herpesvirus thymidine kinase for its 5-substituted-2′-deoxyuridine substrates is reviewed herein.

Analogues of uracil nucleosides with intrinsic fluorescence (NIF-analogues): synthesis and photophysical properties

Uridine cannot be utilized as fluorescent probe due to its extremely low quantum yield. For improving the uracil fluorescence characteristics we extended the natural chromophore at the C5 position by coupling substituted aromatic rings directly or via an alkenyl or alkynyl linker to create fluorophores. Extension of the uracil base was achieved by treating 5-I-uridine with the appropriate boronic acid under the Suzuki coupling conditions. Analogues containing an alkynyl linker were obtained from 5-I-uridine and the suitable boronic acid in a Sonogashira coupling reaction. The uracil fluorescent analogues proposed here were designed to satisfy the following requirements: a minimal chemical modification at a position not involved in base-pairing, resulting in relatively long absorption and emission wavelengths and high quantum yield. 5-((4-Methoxy-phenyl)-trans-vinyl)-2'-deoxy-uridine, 6b, was found to be a promising fluorescent probe. Probe 6b exhibits a quantum yield that is 3000-fold larger than that of the natural chromophore (Φ 0.12), maximum emission (478 nm) which is 170 nm red shifted as compared to uridine, and a Stokes shift of 143 nm. In addition, since probe 6b adopts the anti conformation and S sugar puckering favored by B-DNA, it makes a promising nucleoside analogue to be incorporated in an oligonucleotide probe for detection of genetic material.

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

This review article summarizes the results of a long-term investigation of 5-alkoxymethyluracil analogues and is aimed, in particular, at methods of syntheses. Most of the presented compounds were synthesized in order to evaluate their biological activity, therefore, a brief survey of biological activity, especially antiviral, cytotoxic and antibacterial, is also reported.

Synthesis and Enzymatic Transformations of 5-Halo-6-Methoxy-5,6-Dihydro Derivatives of 5-[1-Methoxy-2-halo(or 2,2-dihalo)ethyl]-2′-deoxyuridines as Potential Herpes Simplex Virus Inhibitors

The 5-halo-6-methoxy-5,6-dihydro derivatives of 5-[1-methoxy-2-halo(or 2,2-dihalo)ethyl]-2'-deoxyuridines (3-12) were synthesized and investigated as potential anti-herpes agents. These 5,6-dihydro derivatives were designed to act as potential prodrugs to 5-[1-methoxy-2-halo(or 2,2-dihalo)ethyl]-2'-deoxyuridines (2a-e), with enhanced metabolic stability, and ready conversion to the parent molecules. These 5,6-disubstituted-5,6-dihydro analogs are stable to E. coli thymidine phosphorylase, and undergo regeneration of the 5,6-olefinic bond to provide parent moieties (2a-e), upon incubation with glutathione at 37 degrees C. The compounds (3-12) themselves were found to be non-inhibitory against herpes simplex virus type-1 (HSV-1), likely due in part to their inability to undergo conversion to parent compounds in cell culture medium.

Synthesis and in vitro anti-mycobacterial activity of 5-substituted pyrimidine nucleosides

Mycobacterium tuberculosis and Mycobacterium avium infections cause the two most important mycobacterioses, leading to increased mortality in patients with AIDS. Various 5-substituted 2'-deoxyuridines, uridines, 2'-O-methyluridine, 2'-ribofluoro-2'-deoxyuridines, 3'-substituted-2',3'-dideoxy uridines, 2',3'-dideoxyuridines, and 2',3'-didehydro-2',3'-dideoxyuridines were synthesized and evaluated for their in vitro inhibitory activity against M. bovis and M. avium. 5-(C-1 Substituted)-2'-deoxyuridine derivatives emerged as potent inhibitors of M. avium (MIC90 = 1-5 microg/mL range). The nature of C-5 substituents in the 2'-deoxyuridine series appeared to be a determinant of anti-mycobacterial activity. This new class of inhibitors could serve as useful compounds for the design and study of new anti-tuberculosis agents.

5-Bromo (or chloro)-6-azido-5,6-dihydro-2' -deoxyuridine and -thymidine derivatives with potent antiviral activity

Synthesis, antiviral, and cytotoxic activities of 5-bromo (or chloro)-6-azido-5,6-dihydro-2' -deoxyuridine (4,5) and -thymidine (6,7) are reported. Compounds 4 and 5 exhibited a broad spectrum of antiherpes activity against (HSV-1, HSV-2, HCMV, and VZV).

Synthesis of 5-[1-hydroxy (or methoxy)-2,2-dihaloethyl]-2'- deoxyuridines with antiviral and cytotoxic activity

The 5-[1-hydroxy (or methoxy)-2,2-dihaloethyl]-2'-deoxyuridines (3-12, Cl, Br and/or I) were synthesized by the addition of HOX or CH3OX (X = Cl, Br, I) to the vinyl substituent of the respective (E)-5-(2-halovinyl)-2'-deoxyuridines (1a-c). In vitro antiviral (HSV-1, HSV-2, HCMV, VZV, EBV) and cytotoxic (L1210) activities were determined. The 5-(1-hydroxy-2,2-dihaloethyl) series were generally more active than the 5-(1-methoxy-2,2-dihaloethyl) series against HSV-1, HSV-2, VZV and EBV. Anti-HSV-1 activity was dependent upon the steric orientation and/or hydrophobic properties of the halogen atom(s), with -CH(OH)CHBr(I) and -CH(OH)CHBr2 C-5 substituents providing the most potent activity. 5-(1-Hydroxy-2-bromo-2-iodoethyl)-2'-deoxyuridine (6), which exhibited the most potent anti-HSV-1 activity, was 12-fold less active than acyclovir. In contrast, the halogen atom(s) were not determinants of anti-VZV activity, where the approximately equipotent 5-(1-hydroxy-2,2-dihaloethyl) compounds (3, 4, 5, 6) exhibited anti-VZV activity comparable to that of acyclovir. All of the 5-(1-hydroxy (or methoxy)-2,2-dihaloethyl) analogs (3-12) were inactive against HCMV. The 5-(1-hydroxy-2-chloro-2-iodoethyl) compound (4) was an active cytotoxic agent as determined in the in vitro L1210 screen. The compounds 3-12 were non-toxic to uninfected host cells. The inhibitory effect on cell proliferation diminished upon replacement of the 5-(1-hydroxy-2,2-dihaloethyl) substituents of 3-6 with the corresponding 5-(1-methoxy-2,2-dihaloethyl) substituents (7-12).