Wine extracts from Sardinian grape varieties attenuate membrane oxidative damage in Caco-2 cell monolayers.

One of the most important sites of polyphenol action seems to be in the gastrointestinal system before absorption. We investigated the ability of three wine phenolic extracts, obtained from grape varieties grown in Sardinia, Cannonau (red), Vermentino and Malvasia (white), to exert an antioxidant action against tert-butyl hydroperoxide (TBH)-induced oxidative damage to Caco-2 cell monolayers as a model system of the human intestine. TBH treatment caused the disruption of epithelial integrity, measured as transepithelial electrical resistance, and markers of the peroxidation process of membrane lipids, MDA, fatty acid hydroperoxides and 7-ketocholesterol. All wine extracts were able to counteract the oxidising action of TBH and, in spite of the differences in phenolic composition, exerted a comparable activity. Our findings point out a direct antioxidant action of the wine extracts on enterocytes exposed to oxidising species and further support the opinion that total phenolic content is not essential for antioxidant activity.

Simultaneous determination of polyphenolic compounds in red and white grapes grown in Sardinia by high performance liquid chromatography-electron spray ionisation-mass spectrometry.

A new method for the identification and the quantification of nonanthocyanin phenolic compounds from six Vitis Vinifera grape varieties native to Sardinia (three native: Vermentino, Malvasia and Cannonau and three non-native types: Chardonnay, Sauvignon and Cabernet Sauvignon; Argiolas vineyard) was developed. This rapid and selective method employs LC/ESI-MS in negative mode. Different solvents extraction and different sorbents for purification were compared to the direct analysis of the initial extracts without further sample preparation. A total of 54 phenolic compounds were identified either in the freeze-dried skins or seeds, including nonflavonoids (hydroxybenzoic and hydroxycinnamic acids and their derivatives, stilbenes) and flavonoids (flavanols, flavonols, dihydroxyflavonols).

Inhibition of hepatitis C replicon RNA synthesis by beta-D-2'-deoxy-2'-fluoro-2'-C-methylcytidine: a specific inhibitor of hepatitis C virus replication.

beta-D-2'-Deoxy-2'-fluoro-2'-C-methylcytidine (PSI-6130) is a cytidine analogue with potent and selective anti-hepatitis C virus (HCV) activity in the subgenomic HCV replicon assay, 90% effective concentration (EC90)=4.6 +/- 2.0 microM. The spectrum of activity and cytotoxicity profile of PSI-6130 was evaluated against a diverse panel of viruses and cell types, and against two additional HCV-1b replicons. The S282T mutation, which confers resistance to 2'-C-methyl adenosine and other 2'-methylated nucleosides, showed only a 6.5-fold increase in EC90. When assayed for activity against bovine diarrhoea virus (BVDV), which is typically used as a surrogate assay to identify compounds active against HCV, PSI-6130 showed no anti-BVDV activity. Weak antiviral activity was noted against other flaviviruses, including West Nile virus, Dengue type 2, and yellow fever virus. These results indicate that PSI-6130 is a specific inhibitor of HCV. PSI-6130 showed little or no cytotoxicity against various cell types, including human peripheral blood mononuclear and human bone marrow progenitor cells. No mitochondrial toxicity was observed with PSI-6130. The reduced activity against the RdRp S282T mutant suggests that PSI-6130 is an inhibitor of replicon RNA synthesis. Finally, the no-effect dose for mice treated intraperitoneally with PSI-6130 for six consecutive days was > or =100 mg/kg per day.

Synthesis and antiviral activity of 2'-deoxy-2'-fluoro-2'-C-methyl purine nucleosides as inhibitors of hepatitis C virus RNA replication.

A series of purine nucleosides containing the 2'-deoxy-2'-fluoro-2'-C-methylribofuranosyl moiety were synthesized and evaluated as potential inhibitors of the hepatitis C virus in vitro. Of the nucleosides that were synthesized, only those possessing a 2-amino group on the purine base reduced the levels of HCV RNA in a subgenomic replicon assay.

N4-hydroxycytosine dioxolane nucleosides and their activity against hepatitis B virus.

Novel racemic, D- and L-beta-dioxolane N4-hydroxycytosine nucleosides have been synthesized and evaluated for their activity against hepatitis B virus. None of the synthesized nucleosides demonstrated selective anti-HBV activity.

Unusual olefin formation by PhSe-F trans-elimination.

A new approach to the synthesis of 2',3'-didehydro-2',3-dideoxynucleosides was described in excellent yield through unusual olefin formation by PhSe-F trans-elimination.

Synthesis of N3,5'-cyclo-4-(beta-D-ribofuranosyl)-vic-triazolo[4,5-b]pyridin-5-one and its 3'-deoxysugar analogue as potential anti-hepatitis C virus agents.

We recently discovered a novel compound, identified as N3, 5-cyclo-4-(beta-D-ribofuranosyl)-vic-triazolo[4,5-b]pyridinin-5-one, with anti-hepatitis C virus (HCV) activity in vitro. The structure was confirmed by chemical synthesis from 2-hydroxy-5-nitropyridine. It showed anti-HCV activity with EC50= 19.7 microM in replicon cells. Its 3'-deoxy sugar analogue was also synthesized, but was inactive against HCV in vitro.

Design, synthesis, and antiviral activity of 2'-deoxy-2'-fluoro-2'-C-methylcytidine, a potent inhibitor of hepatitis C virus replication.

The pyrimidine nucleoside beta-d-2'-deoxy-2'-fluoro-2'-C-methylcytidine (1) was designed as a hepatitis C virus RNA-dependent RNA polymerase (HCV RdRp) inhibitor. The title compound was obtained by a DAST fluorination of N(4)-benzoyl-1-(2-methyl-3,5-di-O-benzoyl-beta-d-arabinofuranosyl]cytosine to provide N(4)-benzoyl-1-[2-fluoro-2-methyl-3,5-di-O-benzoyl-beta-d-ribofuranosyl]cytosine. The protected 2'-C-methylcytidine was obtained as a byproduct from the DAST fluorination and allowed for the preparation of two biologically active compounds from a common precursor. Compound 1 and 2'-C-methylcytidine were assayed in a subgenomic HCV replicon assay system and found to be potent and selective inhibitors of HCV replication. Compound 1 shows increased inhibitory activity in the HCV replicon assay compared to 2'-C-methylcytidine and low cellular toxicity.

Synthesis of N3,5'-cyclo-4-(beta-D-ribofuranosyl)-vic-triazolo[4,5-b]pyridin-5-one, a novel compound with anti-hepatitis C virus activity.

A novel anti-hepatitis C virus (HCV) agent, N(3),5'-cyclo-4-(beta-D-ribofuranosyl)-vic-triazolo[4,5-b]pyridinin-5-one, was identified, and the structure was confirmed by chemical synthesis from 2-hydroxy-5-nitropyridine.

Synthesis of beta-enantiomers of N4-hydroxy-3'-deoxypyrimidine nucleosides and their evaluation against bovine viral diarrhoea virus and hepatitis C virus in cell culture.

N4-Hydroxycytidine (NHC) was recently reported to have anti-pestivirus and anti-hepacivirus activity. It is thought that this nucleoside acts as a weak alternative substrate for the hepatitis C virus (HCV) polymerase. In addition to NHC, 3'-deoxyuridine (3'-dU) was found to inhibit bovine diarrhoea virus (BVDV) production by 1 log10 at 37.2 microM. These initial findings prompted the synthesis of beta-D and beta-L analogues of (i) base-modified 3'-deoxy-NHC; (ii) 3'-deoxyuridine; and 3'-deoxycytidine. The antiviral activity of these 42 nucleosides was evaluated against BVDV and HCV bicistronic replicon in cell culture. Among the NHC analogues, the antiviral activity observed for the beta-L-3'-deoxy-5-fluoro-derivative 1-(3-deoxy-beta-L-erythro-pentofuranosyl)-5-fluoro-4-hydroxyaminopyrimidin-2(1H)-one and the beta-D-3'-deoxy-5-iodo-derivative 1-(3-deoxy-beta-D-erythro-pentofuranosyl)-5-iodocytosine in the replicon system (1 log10 reduction at 100 microM) was due to the concomitant toxicity towards intracellular ribosomal RNA levels (CC90 equal or lower than the EC90). In conclusion, none of the newly synthesized derivatives exhibited enhanced antiviral activity compared to the parent nucleoside NHC.