Design, Synthesis, and Biological Evaluation of Novel C5-Modified Pyrimidine Ribofuranonucleosides as Potential Antitumor or/and Antiviral Agents.

BACKGROUND: Nucleoside analogues are well-known antitumor, antiviral, and chemotherapeutic agents. Alterations on both their sugar and the heterocyclic parts may lead to significant changes in the spectrum of their biological activity and the degree of selective toxicity, as well as in their physicochemical properties. METHODS: C5-arylalkynyl-ß-D-ribofuranonucleosides 3-6, 3΄-deoxy 12-15, 3΄-deoxy-3΄-C-methyl- ß-D-ribofurananucleosides 18-21 and 2΄-deoxy-ß-D-ribofuranonucleosides 23-26 of uracil, were synthesized using a one-step Sonogashira reaction under microwave irradiation and subsequent deprotection. RESULTS: All newly synthesized nucleosides were tested for their antitumor or antiviral activity. Moderate cytostatic activity against cervix carcinoma (HeLa), murine leukemia (L1210) and human lymphocyte (CEM) tumor cell lines was displayed by the protected 3΄-deoxy derivatives 12b,12c,12d, and the 3΄-deoxy-3΄-methyl 18a,18b,18c. The antiviral evaluation revealed appreciable activity against Coxsackie virus B4, Respiratory syncytial virus, Yellow Fever Virus and Human Coronavirus (229E) for the 3΄-deoxy compounds 12b,14, and the 3΄-deoxy-3΄-methyl 18a,18c,18d, accompanied by low cytotoxicity. CONCLUSION: This report describes the total and facile synthesis of modified furanononucleosides of uracil, with alterations on both the sugar and the heterocyclic portions. Compounds 12b,14 and 18a,c,d showed noticeable antiviral activity against a series of RNA viruses and merit further biological and structural optimization investigations.

Unsaturated dideoxy fluoro-ketopyranosyl nucleosides as new cytostatic agents: a convenient synthesis of 2,6-dideoxy-3-fluoro-4-keto-beta-D-glucopyranosyl analogues of uracil, 5-fluorouracil, thymine, N4-benzoyl cytosine and N6-benzoyl adenine.

The beta-protected nucleosides of uracil (2a), 5-fluorouracil (2b), thymine (2c), N(4)-benzoyl cytosine (2d) and N(6)-benzoyl adenine (2e) were synthesized by condensation of the peracetylated 3-deoxy-3-fluoro-D-glucopyranose (1) with the corresponding silylated bases. The nucleosides were deacetylated and several subsequent protection and deprotection steps afforded the partially acetylated analogues 6a-e. Selective iodination followed by hydrogenation gave the acetylated dideoxy analogues of uracil (8a), 5-fluorouracil (8b), thymine (8c), N(4)-benzoyl cytosine (8d) and N(6)-benzoyl adenine (8e), respectively. Finally, direct oxidation of the free hydroxyl group at the 4'-position of 8a-e, and simultaneous elimination reaction of the beta-acetoxyl group, afforded the desired unsaturated 2,6-dideoxy-3-fluoro-4-keto-beta-D-glucopyranosyl derivatives 9a-e. The new analogues were evaluated for antiviral and cytostatic activity. Compounds 9a-e were not active against a broad panel of DNA and RNA viruses at subtoxic concentrations. However, they were markedly cytostatic against a variety of tumor cell lines. The compounds should be regarded as potential new lead compounds to be further investigated for anticancer therapy.