Una mirada actual de la vitamina C en salud y enfermedad / Vitamin C in health and disease: a current perspective

RESUMEN La vitamina C es uno de los antioxidantes más conocidos. Su ingesta ha sido asociada a un sinnúmero de beneficios, algunos de los cuales tienen un sustento científico débil o inexistente. En esta revisión se presentan en forma resumida aspectos biológicos que determinan la homeostasis de la vitamina C y se discute la información disponible sobre sus posibles efectos benéficos y su ingesta, en diversos países con especial énfasis en algunos grupos de riesgo. También se presentan sus efectos benéficos en inflamación, cáncer y enfermedades cardiovasculares, así como su acción de inmunomodulador y regulador epigenético. Se revisan también algunas fuentes dietarias de vitamina C y los factores que influyen en su estabilidad. Terminando con un análisis general de los trabajos relacionados con conducta de vida saludable en países latinoamericanos, que reflejan los malos hábitos alimentarios y que podrían dar cuenta de una hipovitaminosis de vitamina C aún no reportada y repercutir en el desarrollo de envejecimiento precoz y enfermedades crónicas no transmisibles.

ABSTRACT Vitamin C is a well-known antioxidant. Its intake has been associated with a number of benefits, some of which lack a scientific basis. This review summarizes important biological aspects that determine vitamin C homeostasis, discusses the available information on its possible beneficial effects and its intake in various countries, with special emphasis on some risk groups. The beneficial effects of this vitamin in inflammation, cancer and cardiovascular disease are also summarized, as well as its role as immuno-modulator and epigenetic regulator. Dietary sources of vitamin C and the factors that influence its stability are also presented. Finally, an overview of the research conducted on healthy lifestyles in Latin-American countries are presented. This research summarized provides evidence of poor eating habits, which could account for a vitamin C hypovitaminosis not yet reported that could be associated with unhealthy ageing and the development of non-transmissible chronic diseases.

Bonding Effectiveness of Universal Adhesive to Intracoronal Bleached Dentin Treated with Sodium Ascorbate

Abstract This study evaluated the effect of restorative protocol with sodium ascorbate on the shear bond strength (SBS) of a universal adhesive to intracoronal bleached dentin. One hundred-and-twenty bovine dentin fragments were randomly divided into 12 groups (n=10), according to the bleaching procedure (unbleached and bleached) and restorative protocol (no treatment, 10% sodium ascorbate -10SA, 35% sodium ascorbate -35SA and two-step etch-and-rinse -ER or one-step self-etch -SE Scotchbond universal adhesive approaches). Four whitening sessions were performed using 35% hydrogen peroxide. The samples from control groups were kept in relative humidity at 37 °C. Immediately after bleaching procedures, the assigned antioxidant solution was applied on dentin and restorative procedures were performed following either the ER or the SE approach. After 24 h, the specimens were subjected to SBS test. Data (MPa) were analyzed by ANOVA and Tukey's test (?=0.05). Lower SBS values were found for bleached specimens (8.54 MPa) compared with those unbleached (12.13 MPa) (p<0.05). The bond strength of the sodium ascorbate-treated groups was higher than those untreated, regardless of the strategy employed (p<0.05). Groups restored without sodium ascorbate showed lower bond strength values for both ER (8.32 MPa) and SE (8.28 MPa) adhesive strategies. The group treated with 10SA submitted to ER approach (10.14 MPa) was similar to untreated groups (p>0.05). It may be concluded that bond strength of composite resin to intracoronal dentin was affected by restorative protocol and reduced by bleaching.

Resumo Este estudo avaliou o efeito do protocolo restaurador empregando ascorbato de sódio na resistência ao cisalhamento do adesivo universal à dentina intracoronária clareada. Cento e vinte fragmentos de dentina bovina foram aleatoriamente divididos em doze grupos (n=10), de acordo com o procedimento clareador (clareados e não clareados) e protocolo restaurador (sem tratamento, ascorbato de sódio 10% (10AS), ascorbato de sódio (35AS) e estratégia de condicionamento total de dois passos (ER) ou estratégia autocondicionante de um passo (SE) com o sistema adesivo Scotchbond universal. Quatro sessões de clareamento foram realizadas empregando peróxido de hidrogênio a 35%. Os espécimes do grupo controle foram mantidos em umidade relativa a 37 °C. Imediatamente após os procedimentos de clareamento, as soluções antioxidantes selecionadas foram empregadas na dentina e os procedimentos restauradores foram realizados seguindo as estratégias ER ou SE. Após 24 h, os espécimes foram submetidos ao teste de resistência ao cisalhamento. Os dados (MPa) foram analisados pela ANOVA e teste de Tukey (?=0,05). Os menores valores de resistência ao cisalhamento foram encontrados para os espécimes clareados (8,54 MPa) comparados com aqueles não clareados (12,13 MPa) (p<0,05). A resistência de união dos grupos tratados com ascorbato de sódio foi maior que aqueles não tratados (p<0,05), independentemente da estratégia empregada. Grupos restaurados sem ascorbato de sódio demonstraram menores valores de resistência de união para ambas as estratégias adesivas ER (8,32 MPa) e SE (8,28 MPa) (p<0,05). O grupo tratado com ascorbato de sódio a 10% submetido à estratégia ER (10,14 MPa) foi similar ao não tratado (p>0,05). Pode ser concluído que a resistência de união da resina composta à dentina intracoronária foi afetada pelo protocolo restaurador e reduzida pelo clareamento.

Effects of alpha-tocopherol on fracture resistance after endodontic treatment, bleaching and restoration

Abstract This study evaluated the effects of 10% alphatocopherol on the fracture resistance of endodontically treated teeth subjected to tooth bleaching with hydrogen peroxide and immediately restored with composite resin. Fifty bovine incisors were selected, including 10 sound teeth that constituted the control group (G1 (C)). The remaining 40 teeth, which were endodontically treated, were divided into four groups (n = 10): G2 (CR), consisting of teeth immediately restored with composite resin; G3 (HP + CR), consisting of teeth subjected to tooth bleaching with 38% hydrogen peroxide and immediately restored with composite resin; G4 (HP + SA + CR), which received treatment similar to that used for G3, but with 10% sodium ascorbate gel applied after the bleaching protocol; and G5 (HP + AT + CR), which was similar to G4 but included 10% alphatocopherol gel as an antioxidant. After 24 h, composite restorations were performed, and teeth were subjected to a fracture resistance test at a speed of 0.5 mm/min in an electromechanical testing machine. The axial force was applied with an angle of incidence of 135° relative to the long axis of the root. Data were subjected to ANOVA and Tukey tests (p = 0.05). G1 exhibited the highest fracture resistance (p < 0.05). No significant differences among the other experimental groups were observed. The 10% sodium ascorbate and 10% alphatocopherol gels did not improve the fracture resistance of endodontically treated teeth subjected to bleaching with 38% hydrogen peroxide.

Influence of Vitamin C and Maltose on the Accuracy of Three Models of Glucose Meters

No abstract available.

Comparative Study on Bowel Preparation Efficacy of Ascorbic Acid Containing Polyethylene Glycol by Adding Either Simethicone or 1 L of Water in Health Medical Examination Patients: A Prospective Randomized Controlled Study / 대한소화기학회지

BACKGROUND/AIMS: There are no studies that looked into the bubble eliminating efficacy of polyethylene glycol with ascorbic acid (PEGA), which has been one of the shortcomings of polyethylene glycol (PEG). In this study, we compared newly introduced PEGA regimen by adding either simethicone or 1 L of water. METHODS: A prospective randomized controlled study was carried out at Dongguk Universtiy Gyeongju Hospital from July 2014 to September 2014. A total of 90 patients were randomly assigned to 3 groups; PEGA group (n=30) which served as control, simethicone addition group (n=30) to which simethicone 400 mg was additionally prescribed, and water addition group (n=30) to whom additional 1 L of water was given. Cleansing effectiveness, gas elimination efficacy, side effects, and patient satisfaction were compared between the groups. RESULTS: PEGA group demonstrated the highest cleansing effectiveness, but there was no statistically significant difference among the groups. Simethicone addition group showed significantly lesser amount of bubbles than the other groups (2.57±2.05 vs. 1.10±1.83 vs. 2.60±2.84, p=0.017). The rates of side effects in each group were 20.00% vs. 16.77% vs. 53.33%. Water addition group had significantly more side effects than the PEGA group and the simethicone addition group (p=0.003). The patient satisfaction score of each group was 3.37±0.85 vs. 3.73±0.74 vs. 3.20±0.66 with simethicone addition group showing significantly higher satisfaction than water addition group (p=0.020). CONCLUSIONS: PEGA bowel preparation agent showed satisfactory bowel cleansing despite the decrease in dosage, and addition of simethicone resulted in better bubble elimination.

[ study for vitamin C stability in some kinds of baby food]

Due to the biological importance of vitamin C and the high ability of degradation, vitamin C content was studied on 152 samples of three baby food products [wet food, dry food, some fruit juices]. The vitamin C composition of all samples was determined in triplicate, using the method of High Performance Liquid Chromatography HPLC [C18 Colum and UV-Detector and the results were compared with the concentrations which are mentioned on the label of the samples. Vitamin C stability was studied in different samples, by exposing them to the accelerated and long - duration stability tests conditions. In addition to the study of vitamin C stability in different kinds of fruit juices and wet baby food after opening the samples and preserving them in normal conditions [4 [degree sign] c]. The results showed that the concentrations which are mentioned on the label of different samples were true except some of them which showed either increase or decrease in the concentration of vitamin C. And the accelerated stability studies showed that the Vitamin C content declined when the temperature increased and the largest lost was when the samples exposed to the temperature of [40 [degree sign] +/- 2 [degree sign] c], and this content of vitamin C declined when the samples exposed to the sun light at the same temperature [25 [degree sign] +/- 2 [degree sign] c]. And the results showed that Vitamin C content in the samples declined and affected by the time factor when the samples were preserved in the normal conditions [4 [degree sign] c], and this content in the stored and handmade fruit juices and wet baby food declined in large percentage after opening these samples and preserving them in normal conditions [4 [degree sign] c

2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK3) and ascorbic acid (vitamin C, VC) is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H2O2) through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H2O2 production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H2O2 production. The compound 2-bromo-1,4-naphthoquinone (BrQ), in which the bromine atom substituted the methyl group in VK3, was approximately 10- and 19-fold more efficient than VK3 in terms of oxygen consumption and H2O2 production, respectively. The ratio [H2O2]produced / [naphthoquinone]consumed was 68 ± 11 and 5.8 ± 0.2 (µM/µM) for BrQ and VK3, respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK3 and BrQ reacted with glutathione (GSH), but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG). The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK3/VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK3 with BrQ will open new lines of investigation regarding this approach to cancer treatment.

Recovery of silver residues from dental amalgam

Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5 percent HNO3, followed by precipitation with 20 percent NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20 percent NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

Comparison of the effect of hydrogel and solution forms of sodium ascorbate on orthodontic bracket-enamel shear bond strength immediately after bleaching: An in vitro study.

Aim: This study compared the effects of hydrogel and solution forms of sodium ascorbate (SA) with two different application times on bracket bond strength subsequent to bleaching. Materials and Methods: A total of 72 sound premolars were randomly divided into six groups (n = 12): An unbleached control group (group one) and five experimental groups of carbamide peroxide. Specimens in group two were bonded immediately after bleaching; specimens in groups three and four were bleached, then treated with SA solution for ten minutes and three hours, respectively, and then bonded. In groups five and six, SA hydrogel was used and the specimens were prepared similar to groups three and four, respectively. Following debonding, bond strengths were recorded in MPa. To evaluate the amount of resin left on the enamel surfaces, adhesive remnant index (ARI) scores were used. Statistical Analysis: The bond strength data were analyzed with ANOVA and pairwise comparisons were made by Tukey test. The ARI data were subjected to Kruskal-Wallis test and two-by-two comparisons were made by the Mann-Whitney U test. Results: There were significant differences in bond strengths between the groups ( P < 0.0005). However, the differences between groups three, four, five and six were not significant. Furthermore, there were no significant differences between group one and groups four and six, whereas the differences between the other groups were significant ( P < 0.05). Regarding ARI, there were significant differences among the groups ( P = 0.004). Conclusion: Bleaching significantly decreased the bracket bond strength. Compromised bonding was reversed with a three-hour application of both forms of SA.

In vitro response of encapsulated somatic embryos of Lagerstroemia indica L.

A method to produce encapsulatable units for synthetic seeds was developed in L. indica. Somatic embryos were harvested from leaf derived embryogenic callus on Murashige and Skoog's basal medium supplemented with 2, 4-dichlorophenoxy acetic acid (2, 4-D, 0.5 mg/l), 6-benzyl amino purine (BAP, 1 mg/l) and ascorbic acid (AA, 50 mg/l). The embryos were encapsulated in alginate beads and dehydrated. Germination ability of the artificial seeds were investigated. The frequency of regeneration from the encapsulated embryos was significantly affected by (i) the concentration of alginate (ii) the duration of storage, and (iii) the effect of different types of media. A 2% sodium alginate concentration on MS salts resulted in significantly higher germination frequencies than at other concentrations. L. indica showed maximum germination on MS medium (93.84%) after 6 weeks of culture. The germinated synthetic seeds with well developed roots and shoots were transferred successfully to green house. This is the first report on artificial seeds in Lagerstroemnia indica.

Mecanismo de interferência do ácido ascórbico em ensaios bioquímicos baseados no sistema oxidase/peroxidase (reação de Trinder) / Mechanism of ascorbic acid interference in biochemical tests using peroxide and peroxidase to generate chromophore (Trinder's reaction)

Para esclarecer o mecanismo da interferência do ácido ascórbico na reação de Trinder estudamos as cinéticas de formação e de redução dos cromógenos oxidados, resultantes da reação entre o H2O2, o composto fenólico e a 4-aminofenazona nos ensaios de ácido úrico, colesterol, triglicérides e glicose. Verificamos, também o efeito dos constituintes da reação de Trinder na interferência pelo ácido ascórbico. O ácido ascórbico inibiu todas as reações estudadas, seguindo uma estequiometria de 1:1 com os analitos. O ácido ascórbico diminuiu a quantidade do cremógeno formado na reação do ácido úrico sem alterar a cinética de formação, enquanto que para o colesterol, triglicérides e glicose houve aumento da fase "lag". No entanto, o ácido ascórbico não inibiu a enzima oxidase. A adição de H2O2 aos reagentes não apresentou fase "lag" na presença de ácido ascórbico. Além disso, o ácido ascórbico não reduziu expressivamente os cromógenos formados. Concluímos que o consumo do H2O2 foi o mecanismo predominante da interferência do ácido ascórbico na reação de Trinder. O efeito na cinética de formação dos cromógenos deve-se, possivelmente, à velocidade de geração do H2O2 pelas oxidases específicas.

Influência do estresse nos níveis sangüíneos de lipídios, de ácido ascórbico, de zinco e de outros parâmetros bioquímicos / Stress' influence on blood levels of lipid, ascorbic acid, zinc and other biochemical parameters

Muitos estudos apontam quanto à possibilidade de que o estresse afete a concentração de lipídeos, de ácido ascórbico, de zinco e de outros parâmetros bioquímicos e que estes elementos devem provocar alterações hormonais e bioquímicas, prejudicando o sistema cardiovascular. Assim, esta pesquisa teve como objetivo verificar o estresse em suas diferentes modalidades: tolerância, tensão, fontes, estado e vulnerabilidade e depois correlacionar as respostas de tais questionários com as alterações bioquímicas propostas em análise. A população examinada foi de 29 pacientes trabalhadores ou estudantes da Universidade federal de Santa Catarina - Brasil. Observou-se que a maioria das pessoas, da comunidade universitária analisada, convive com problemas de estresse e que os indivíduos mais tolerantes ao estresse são os menos vulneráveis. Da mesma forma, foi possível observar que os indivíduos mais tensos foram aqueles com estado de sofrimento ou sofrimento severo. Para correlação das análises bioquímicas o questionário sobre estado de estresse foi o que mais apresentou alterações significativas com os diversos parâmetros bioquímicos analisados. Nesta pesquisa pode-se notar que os problemas de estresse provocam um aumento de colesterol total e LDL-colesterol e uma pequena diminuição da fração HDL-colesterol, cálcio, magnésio, ácido ascórbico e zinco. Contudo, em nenhum dos questionários utilizados observou-se qualquer correlação entre os problemas de estresse e as análises bioquímicas como o fósforo, sódio, potássio e vitamina B12. Conclui-se que os parâmetros bioquímicos são ferramentas importantes na análise do estresse e que este deve acelerar o curso da aterosclerose coronariana.

Biossíntese de ácido L-ascórbico em plantas: estudo com supostos precursores / L-ascorbic acid biosynthesis in plants: study with supposed of precursors

Poucos trabalhos foram publicados envolvendo a biossíntese do AA em plantas desde sua descoberta em 1928. O mecanismo de biossíntese era um mistério até 1998 quando Wheeler, Jones e Smirnoff demonstraram que a L-galactose é precursor chave desta importante vitamina. Utilizando-se acúcares marcados e frios pudemos confirmar o mecanismos Smirnoff-Wheeler de biossíntese do AA. Neste trabalho nós apresentamos os resultados alcançados usando alguns supostos precursores e alguns frutos como o morango, a goiaba e o mamão papaya, e alguns legumes como o brócolis, alguns deles ricos em AA. As técnicas de HPLC e espectrofometria UV/VIS foram utilizadas na determinação do AA. Os vegetais foram mantidos...

La vitamina C y sus propiedades antimutagénicas / The antimuthagenic properties of vitamin C

Se efectuó el análisis de algunas características de la vitamina C. Para ello se consideraron sus propiedades químicas y biológicas así como su impacto en la salud. Se revisaron las principales evidencias sobre su capacidad antimutagénica (y potencialmente anticarcinogénica) en diversos organismos y sistemas de prueba, y se consideró la posible aplicación en el humano

Spectrophotometric and spetrofluorimetric methods for determination of rutin in presence of ascorbic acid

Two simple, sensitive and specific methods for the determination of rutin in tablets in presence of ascorbic acid are presented. The first method depends upon measuring the first derivative response of rutin in methanolic/NaOH solution at 430 nm, where ascorbic acid showed no interference. The second method utilized the fluorescence characteristics of rutin/AlCl3 complex in methanol, where ascorbic acid has no contribution. The validity of the proposed methods was proved by analysis of synthetic mixtures of rutin and ascorbic acid and have been applied successfully to the analysis of rutin in tablets

Ascorbate-dependent formation of hydroxyl radicals in the presence of iron chelates.

The autoxidation of L-ascorbate on incubation in saline phosphate buffer (pH 7.4) is accompanied by hydroxyl radical (.OH) generation. The metal chelator EDTA showed significant inhibition of ascorbate autoxidation and ascorbate-dependent .OH release. On the other hand, Fe2+ (EDTA) greatly augmented both ascorbate autoxidation and ascorbate-dependent .OH production. The biological iron chelating compounds such as ATP, ADP, citrate and pyrophosphate suppressed both ascorbate autoxidation and ascorbate-mediated .OH production, thereby indicating that these compounds suppress the activating effect of iron. Ascorbate autoxidation and ascorbate-dependent .OH formation, stimulated by Fe2+ (EDTA) were significantly inhibited by .OH scavengers, namely mannitol, thiourea and sodium formate, as well as by catalase and to a lesser extent by bovine serum albumin, superoxide dismutase (native and heat denatured) and heat denatured catalase.

Some heterocycles from dehydro-l-ascorbic acid bishydrazones

Controlled reaction of dehydro-L-ascorbic acid [I] with one mole of o- tolylhydrazine gave the 2-[o-tolyl] hydrazone II. The reaction of II with phenyl- and o-tolylhydrazine afforded the bis-hydrazones III and V, which underwent acetylation to the di-O-acetyl derivatives IV and VI, respectively. Oxidative cyclization of III and V with cupric chloride gave the 3,6-anhydro derivatives XIII and XV, respectively. The bishydrazone III underwent rearrangement to the pyrazolodione VII by the action of alkali, followed by acidification. Treatment of VII with acetic anhydride in pyridine afforded the tri-O-acetyl derivative VIII. Periodate oxidation of VII led to the aldehyde IX, which was converted to the pyrazole oxime XIX and thiosemicarbazone XXII by treatment with hydroxylamine and thiosemicarbazide, respectively. Acetylation of XXII by boiling with acetic anhydride yielded the thiazoline XXII. Compound II underwent dehydrative acetylation into compound XVII. The latter reacted with methylhydrazine to give XVIII. The IR and PMR of some of the compounds were investigated