RESUMO
Avian leukosis virus subgroup J (ALV-J), a member of the retroviridae family, can infect both broilers and layers and induce a spectrum of different neoplasms, resulting in serious economic losses in poultry production. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has demonstrated remarkable anti-inflammatory and cancer chemopreventive effects in many animal tumor bioassays, cell culture systems and epidemiological studies. To assess the antiviral effects of EGCG on ALV-J-induced cell apoptosis in vitro, DF-1 cells were treated with different EGCG concentrations (0, 5, 10, 20 and 40 µg/mL), and their antiviral effects were examined at different time points (0, 24, 48, 72 and 96 h) using a variety of assays. EGCG alleviated the ALV-J-induced apoptosis in a dose-dependent manner. Because high concentrations (20 and 40 µg/mL) inhibited DF-1 cell growth, and low concentration (5 µg/mL) did not suppress the ALV-J virus, 10 µg/mL was the most appropriate concentration. After 96 h of incubation, 10 µg/mL EGCG improved the ALV-J-triggered suppression of the nuclear transcription factor system by enhancing cytoplasmic NF-B p50/p65 expression and inhibiting nuclear NF-B p50/p65 expression, resulting in decreased cell apoptosis. These results demonstrated that EGCG inhibited ALV-J-induced apoptosis in DF-1 cells in a dose-dependent manner via the NF-B signaling pathway, and that 10 µg/mL EGCG is the optimal concentration, which may be useful for therapeutic drug design.(AU)
Assuntos
Animais , Galinhas/virologia , Apoptose , Galato de Propila/química , NF-kappa B/análise , Vírus da Leucose AviáriaRESUMO
Avian leukosis virus subgroup J (ALV-J), a member of the retroviridae family, can infect both broilers and layers and induce a spectrum of different neoplasms, resulting in serious economic losses in poultry production. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has demonstrated remarkable anti-inflammatory and cancer chemopreventive effects in many animal tumor bioassays, cell culture systems and epidemiological studies. To assess the antiviral effects of EGCG on ALV-J-induced cell apoptosis in vitro, DF-1 cells were treated with different EGCG concentrations (0, 5, 10, 20 and 40 µg/mL), and their antiviral effects were examined at different time points (0, 24, 48, 72 and 96 h) using a variety of assays. EGCG alleviated the ALV-J-induced apoptosis in a dose-dependent manner. Because high concentrations (20 and 40 µg/mL) inhibited DF-1 cell growth, and low concentration (5 µg/mL) did not suppress the ALV-J virus, 10 µg/mL was the most appropriate concentration. After 96 h of incubation, 10 µg/mL EGCG improved the ALV-J-triggered suppression of the nuclear transcription factor system by enhancing cytoplasmic NF-B p50/p65 expression and inhibiting nuclear NF-B p50/p65 expression, resulting in decreased cell apoptosis. These results demonstrated that EGCG inhibited ALV-J-induced apoptosis in DF-1 cells in a dose-dependent manner via the NF-B signaling pathway, and that 10 µg/mL EGCG is the optimal concentration, which may be useful for therapeutic drug design.
Assuntos
Animais , Apoptose , Galato de Propila/química , Galinhas/virologia , NF-kappa B/análise , Vírus da Leucose AviáriaRESUMO
The kinetic and mechanistic aspects of the visible-light-mediated photodegradation of the phenolic antioxidants (PA), propyl gallate (PG), and t-butylhydroquinone (TBHQ), employing riboflavin (Rf) as photosensitizer, have been studied by time-resolved and stationary techniques. The photosensitizer Rose Bengal (RB) was used for auxiliary experiments. Results show the occurrence of chemical transformations on PA with the participation of electronically excited states of Rf and different reactive oxygen species (ROS) generated from these states. With 0.02 mM Rf and 1.0 mM PA, the electronically excited triplet state of Rf is quenched by PA, in a competitive manner with the dissolved oxygen. As a consequence, a cascade of photoprocesses produces singlet oxygen (O(2)((1)Δ(g))) and H(2)O(2) in the case of PG and, O(2)((1)Δ(g)), H(2)O(2) and HO(â¢) in the case of TBHQ. The participation of these species is supported by experiments of oxygen consumption carried out in the presence of specific ROS scavengers. TBHQ has a relatively high capacity for O(2)((1)Δ(g)) physical deactivation and a low photodegradation efficiency by the oxidative species. Comparatively, it can be asserted that TBHQ has a higher antioxidant capacity than PG.
Assuntos
Antioxidantes/química , Hidroquinonas/química , Luz , Fotólise , Galato de Propila/química , Animais , Fluorimunoensaio , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Medições Luminescentes/métodos , Rosa Bengala/química , Oxigênio Singlete/químicaRESUMO
The antioxidant capacity of butylated hydroxytoluene (BHT; 2,6-di-tert-butyl-p-cresol), propyl gallate (3,4,5-trihydroxybenzoic acid n-propyl ester), resveratrol (trans-3,4',5-trihydroxystilbene), and vitamins C (l-ascorbic acid) and E [(+)-alpha-tocopherol] was studied in chemical and biological systems. The chemical assays evaluated the capacity of these antioxidants to sequester 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS.) and 1,1 diphenyl-2-picrylhydrazyl (DPPH.). A new colorimetric method to determine hydroxyl radical scavenging is also described. The biological tests use the eucaryotic cells of Saccharomyces cerevisiae treated with the antioxidants in the presence of the stressing agents apomorphine, hydrogen peroxide, and paraquat dichloride (methylviologen; 1,1'-dimethyl-4,4'-bipyridinium dichloride). The results in chemical systems showed that all of the antioxidants were able to significantly inhibit the oxidation of beta-carotene by hydroxyl free radicals. The assays in yeast showed that the antioxidant activity of the tested compounds depended on the stressing agent used and the mechanism of action of the antioxidant.