RESUMO
MAIN CONCLUSION: The oxidant/antioxidant balance affects the ripening time of tomato fruit. Ripening of tomato fruit is associated with several modifications such as loss of cell wall firmness and transformation of chloroplasts to chromoplasts. Besides a peak in H2O2, reactive oxygen species (ROS) are observed at the transition stage. However, the role of different components of oxidative stress metabolism in fruit ripening has been scarcely addressed. Two GDP-L-galactose phosphorylase (GGP) Solanum lycopersicum L. cv Micro-Tom mutants which have fruit with low ascorbic acid content (30% of wild type) were used in this work to unravel the participation of ascorbic acid and H2O2 in fruit maturation. Both GGP mutants show delayed fruit maturation with no peak of H2O2; treatment with ascorbic acid increases its own concentration and accelerates ripening only in mutants to become like wild type plants. Unexpectedly, the treatment with ascorbic acid increases H2O2 synthesis in both mutants resembling what is observed in wild type fruit. Exogenous supplementation with H2O2 decreases its own synthesis delaying fruit maturation in plants with low ascorbic acid content. The site of ROS production is localized in the chloroplasts of fruit of all genotypes as determined by confocal microscopy analysis. The results presented here demonstrate that both ascorbic acid and H2O2 actively participate in tomato fruit ripening.
Assuntos
Ácido Ascórbico/metabolismo , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Proteínas de Plantas/metabolismo , Solanum lycopersicum/crescimento & desenvolvimento , Solanum lycopersicum/metabolismo , Ácido Ascórbico/genética , Frutas/genética , Variação Genética , Solanum lycopersicum/genética , Proteínas de Plantas/genéticaRESUMO
Oxidative stress and inflammation are crucial factors that increase with age. In the progression of multiple age-related diseases, antioxidants and bioactive compounds have been recognized as useful antiaging agents. Oxidized or reduced vitamin C exerts different actions on tissues and has different metabolism and uptake. In this study, we analyzed the antiaging effect of vitamin C, both oxidized and reduced forms, in renal aging using laser microdissection, quantitative reverse-transcription polymerase chain reaction, and immunohistochemical analyses. In the kidneys of old SAM mice (10 months of age), a model of accelerated senescence, vitamin C, especially in the oxidized form (dehydroascorbic acid [DHA]) improves renal histology and function. Serum creatinine levels and microalbuminuria also decrease after treatment with a decline in azotemia. In addition, sodium-vitamin C cotransporter isoform 1 levels, which were increased during aging, are normalized. In contrast, the pattern of glucose transporter 1 expression is not affected by aging or vitamin C treatment. We conclude that oxidized and reduced vitamin C are potent antiaging therapies and that DHA reverses the kidney damage observed in senescence-accelerated prone mouse 8 to a greater degree.
Assuntos
Ácido Ascórbico/farmacologia , Ácido Desidroascórbico/farmacologia , Inflamação/genética , Rim/efeitos dos fármacos , Transportadores de Sódio Acoplados à Vitamina C/genética , Envelhecimento/genética , Envelhecimento/patologia , Animais , Ácido Ascórbico/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Transportador de Glucose Tipo 1/genética , Humanos , Inflamação/patologia , Rim/ultraestrutura , Camundongos , Estresse Oxidativo/efeitos dos fármacosRESUMO
Ascorbic acid (AA) is a major redox buffer in plant cells. The role of ethylene in the redox signaling pathways that influence photosynthesis and growth was explored in two independent AA deficient Arabidopsis thaliana mutants (vtc2-1 and vtc2-4). Both mutants, which are defective in the AA biosynthesis gene GDP-L-galactose phosphorylase, produce higher amounts of ethylene than wt plants. In contrast to the wt, the inhibition of ethylene signaling increased leaf conductance, photosynthesis and dry weight in both vtc2 mutant lines. The AA-deficient mutants showed altered expression of genes encoding proteins involved in the synthesis/responses to phytohormones that control growth, particularly auxin, cytokinins, abscisic acid, brassinosterioids, ethylene and salicylic acid. These results demonstrate that AA deficiency modifies hormone signaling in plants, redox-ethylene interactions providing a regulatory node controlling shoot biomass accumulation.
Assuntos
Proteínas de Arabidopsis/genética , Ácido Ascórbico/metabolismo , Etilenos/metabolismo , Monoéster Fosfórico Hidrolases/genética , Reguladores de Crescimento de Plantas/metabolismo , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Ácido Ascórbico/genética , Biomassa , Regulação da Expressão Gênica de Plantas , Mutação , Oxirredução , Monoéster Fosfórico Hidrolases/metabolismo , Fotossíntese/genética , Reguladores de Crescimento de Plantas/genética , Ácido Salicílico/metabolismo , Transdução de Sinais/genéticaRESUMO
Solanum diploconos is an unexploited Brazilian native fruit that belongs to the same genus of important food crops, such as tomato (Solanum lycorpersicum) and potato (Solanum tuberosum). In this study, we determined, for the first time, the profile of bioactive compounds (phenolic compounds, carotenoids, ascorbic acid and tocopherols) of the freeze-dried pulp and peel of Solanum diploconos fruits, as well as of an extract obtained from the whole fruit. Additionally, the antioxidant potential of the whole fruit extract was evaluated in vitro, against reactive oxygen species (ROS) and reactive nitrogen species (RNS). Eighteen phenolic compounds were identified in the peel and pulp and 6 compounds were found in the whole fruit extract. Coumaric, ferulic and caffeic acid derivatives were revealed to be the major phenolic constituents. All-trans-ß-carotene was the major carotenoid (17-38 µg g(-1), dry basis), but all-trans-lutein and 9-cis-ß-carotene were also identified. The peel and pulp presented <2 µg per mL of tocopherols, and ascorbic acid was not detected. The whole fruit extract exhibited scavenging capacity against all tested ROS and RNS (IC50 = 14-461 µg mL(-1)) with high antioxidant efficiency against HOCl. Thus, Solanum diploconos fruits may be seen as a promising source of bioactive compounds with high antioxidant potential against the most physiologically relevant ROS and RNS.
Assuntos
Antioxidantes/análise , Frutas/química , Extratos Vegetais/química , Solanum/química , Antioxidantes/química , Ácido Ascórbico/análise , Ácido Ascórbico/genética , Brasil , Ácidos Cafeicos/análise , Ácidos Cafeicos/química , Carotenoides/análise , Carotenoides/química , Cromatografia Líquida de Alta Pressão , Ácidos Cumáricos/análise , Ácidos Cumáricos/química , Sequestradores de Radicais Livres/análise , Sequestradores de Radicais Livres/química , Peróxido de Hidrogênio , Ácido Hipocloroso , Luteína/análise , Luteína/química , Óxido Nítrico , Ácido Peroxinitroso , Fenóis/análise , Fenóis/química , Espécies Reativas de Nitrogênio/química , Espécies Reativas de Oxigênio/química , Oxigênio Singlete , Superóxidos , Tocoferóis/análise , Tocoferóis/químicaRESUMO
Sugars are part of an integrated redox system, since they are key regulators of respiration and photosynthesis, and therefore of the levels of reducing power, ATP and ROS. These elements are major determinants of the cellular redox state, which is involved in the perception and regulation of many endogenous and environmental stimuli. Our previous findings suggested that early sugar increase produced during compatible Sunflower chlorotic mottle virus (SuCMoV) infection might modulate chlorotic symptom development through redox state alteration in sunflower. The purpose of this work was to characterize redox-related metabolites and gene expression changes associated with high sugar availability and symptom development induced by SuCMoV. The results show that sugar caused an increase in glutathione, ascorbate, pyridine nucleotides, and ATP. In addition, higher sugar availability reduced hydrogen peroxide and ΦPSII. This finding suggests that high sugar availability would be associated with cellular redox alteration and photoinhibitory process. The expression of the genes analyzed was also strongly affected by sugar, such as the down-regulation of psbA and up-regulation of psbO and cp29. The expression level of cytoplasmic (apx-1 and gr)- and chloroplastic (Fe-sod)-targeted genes was also significantly enhanced in sugar-treated leaves. Therefore, all these responses suggest that sugars induce chloroplastic redox state alteration with photoinhibition process that could be contributing to chlorotic symptom development during SuCMoV infection.
Assuntos
Carboidratos/farmacologia , Helianthus/virologia , Folhas de Planta/genética , Potyvirus/patogenicidade , Trifosfato de Adenosina/metabolismo , Antioxidantes/metabolismo , Ácido Ascórbico/genética , Ácido Ascórbico/metabolismo , Carboidratos/análise , Proteínas de Cloroplastos/genética , Proteínas de Cloroplastos/metabolismo , Cloroplastos/genética , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Glutationa/metabolismo , Helianthus/efeitos dos fármacos , Helianthus/genética , Helianthus/metabolismo , Interações Hospedeiro-Patógeno , Peróxido de Hidrogênio/metabolismo , Oxirredução , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Doenças das Plantas/virologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/virologiaRESUMO
Ascorbate is an important antioxidant, which also displays important functions in neuronal tissues, including the retina. The retina is responsible for the initial steps of visual processing, which is further refined in cerebral high-order centers. The retina is also a prototypical model for studying physiologic aspects of cells that comprise the nervous system. Of major importance also is the cellular messenger nitric oxide (NO). Previous studies have demonstrated the significance of NO for both survival and proliferation of cultured embryonic retinal cells. Cultured retinal cells express a high-affinity ascorbate transporter, and the release of ascorbate is delicately regulated by ionotropic glutamate receptors. Therefore, we proposed whether there is interplay between the ascorbate transport system and NO signaling pathway in retinal cells. Here we show compelling evidence that ascorbate uptake is tightly controlled by NO and its downstream signaling pathway in culture. NO also modulates the expression of SVCT-2, an effect mediated by cGMP and PKG. Kinetic studies suggest that NO increases the transport capacity for ascorbate, but not the affinity of SVCT-2 for its substrate. Interestingly, NO utilizes the NF-κB pathway, in a PKG-dependent manner, to modulate both SVCT-2 expression and ascorbate uptake. These results demonstrate that NO exerts a fine-tuned control of the availability of ascorbate to cultured retinal cells and strongly reinforces ascorbate as an important bioactive molecule in neuronal tissues.