Antioxidant and pro-oxidant activity of Vitamin C in oral environment

Chakraborthy, Aratirika; Ramani, Pratibha; Sherlin, Herald J; Premkumar, Priya; Natesan, Anuja

doi:10.4103/0970-9290.142547

Cited by 81 publications

(62 citation statements)

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“…However, clinical studies using antioxidants as an adjuvant to chemotherapy have so far been unsuccessful (10,19,25,28,33,34). L-ascorbic acid may function as either a pro-oxidant or an antioxidant at physiological micromolar concentrations (normal range, <0.1 mM) in the presence of trace amounts of transition metals including copper and iron (20,(34)(35)(36)(37)(38)(39)(40). There is controversy regarding the potential role and dose of L-ascorbic acid that should be recommended for use in cancer therapy (40).…”

Section: Discussionmentioning

confidence: 99%

The enhanced tumor inhibitory effects of gefitinib and L-ascorbic acid combination therapy in non-small cell lung cancer cells

et al. 2017

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Abstract. Despite documentation of successful therapy with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in patients with lung cancer, the response rate of patients treated with this therapy remains low. The present study investigated whether L-ascorbic acid serves an adjuvant role in vitro when combined with the EGFR tyrosine kinase inhibitor gefitinib (Iressa ® ) in lung cancer cell lines. A total of three human lung cancer cell lines were used. The antiproliferative effects and changes in the cell cycle and expression of intracellular signaling molecules, including extracellular signal-regulated kinases (Erk), signal transducer and activator of transcription 3 (Stat3) and protein kinase B (Akt), were measured in cells treated with gefitinib and/or L-ascorbic acid at various concentrations. When combined with gefitinib, L-ascorbic acid exhibited an additive effect on cell proliferation in all gefitinib-sensitive and gefitinib-resistant cell lines. A decrement of ~40% was observed with a low dose 0.5 mM L-ascorbic acid and gefitinib in the relatively gefitinib-resistant A549 cell line (85.6±5.4% with gefitinib alone vs. 52.7±7.3% with combination therapy; P=0.046). The downregulation of intracellular signaling cascades, including EGFR, Akt, Erk and Stat3, was also observed. L-Ascorbic acid serves an adjuvant role when administered in combination with gefitinib; however, the degree of inhibition of cell proliferation differs between lung cancer cell lines.

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Section: Discussionmentioning

confidence: 99%

The enhanced tumor inhibitory effects of gefitinib and L-ascorbic acid combination therapy in non-small cell lung cancer cells

et al. 2017

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“…39 A vitamina C se destaca devido a sua propriedade antioxidante (agente redutor e doador de elétrons), protegendo o organismo contra as ações dos radicais livres; a sua participação em inúmeras reações bioquímicas, principalmente atuando como co-fator enzimático; e a sua capacidade de aumentar a biodisponibilidade do ferro, devido à redução do ferro férrico (Fe 3+ ) a ferro ferroso (Fe 2+ ). 40,41 O teor de compostos fenólicos observado nesta pesquisa foi de 176,3mg EAG/100g, dado que não corroborou o teor de 338,9mg EAG/100g descrito por Rezende et al 42 Dentre as variadas classes de antioxidantes naturais, os compostos fenólicos têm se destacado, devido a suas propriedades de captar radicais livres e, consequentemente, pela capacidade de proteção ao organismo humano. 43 Vale ressaltar que a análise dos compostos fenólicos pode ser influenciada pela natureza do composto, método empregado, solvente utilizado, tamanho da amostra, tempo e condições de armazenamento, padrão utilizado e interferentes (ceras e gorduras).…”

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COMPOSIÇÃO CENTESIMAL, COMPOSTOS BIOATIVOS E PARÂMETROS FÍSICO-QUÍMICOS DO JENIPAPO (Genipa americana L.) IN NATURA

Pacheco

Paz

Silva

et al. 2014

DEMETRA

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Composição centesimal, compostos bioativos e parâmetros físico-químicos do jenipapo (genipa americana L.) in natura Centesimal composition, bioactive compounds, phisicochemical parameters in in natura jenipapo (genipa americana L.) ResumoIntrodução: O cerrado é um bioma diversificado que apresenta inúmeros tipos de espécies frutíferas, dentre as quais se destaca o jenipapo (Genipa americana L). Objetivo: Analisar a composição centesimal, os compostos bioativos e os parâmetros físico-químicos presentes no jenipapo in natura. Metodologia: O jenipapo foi obtido em comércios localizados em Minas Gerais e Goiás. As análises foram realizadas em triplicata e os resultados, expressos como média e desvio-padrão. Umidade, proteínas, lipídios, cinzas, fibras alimentares, vitamina C, acidez total titulável, sólidos solúveis e pH foram determinados por métodos da Association of Official Analytical Chemists e do Instituto Adolfo Lutz. Em adição, as análises de carboidratos "disponíveis" foram realizadas pelo método fenol-sulfúrico e por diferença; os teores de betacaroteno foram analisados por espectrofotometria. A atividade antioxidante foi determinada pelo método de DPPH. Resultados: A polpa do jenipapo apresentou: 70,0% umidade; 0,5% proteínas; 0,0% lipídios; 1,1% cinzas; 6,3% fibras alimentares; 20,1% carboidratos "disponíveis"; 22,1% carboidratos "disponíveis" (por diferença); 26,0mg vitamina C/100g; 0mg betacaroteno/100g; 176,3mg de compostos fenólicos em 100g; pH 3,85; 15,2º Brix sólidos solúveis totais; 0,40% acidez total titulável e 70,2% de capacidade antioxidante. Conclusão: O jenipapo in natura apresentou valores apreciáveis de umidade, carboidratos totais (sobretudo fibras alimentares), vitamina C, compostos fenólicos, acidez, sólidos solúveis e alta atividade antioxidante. Dessa forma, sua inclusão na alimentação poderia melhorar a qualidade da dieta, contribuindo para a segurança alimentar e nutricional da população do cerrado. The in natura jenipapo showed considerable moisture values, total carbohydrates (mainly dietary fiber), vitamin C, phenolic compounds, acidity, soluble solids and high antioxidant activity. Thus, the inclusion of jenipapo in the diet could improve its quality, contributing to food and nutritional security of the cerrado population. Palavras

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“…Both FPPB and BPPB could protect against HgCl 2 ‐provoked lysis of human erythrocytes at a specific concentration range. The observed decrease in the antihemolytic effect of the extracts and ascorbic acid at higher concentrations could be due to the prooxidative tendency of phenolics and antioxidant molecules, including ascorbic acid, at concentrations above a particular threshold …”

Section: Discussionmentioning

confidence: 99%

“…The observed decrease in the antihemolytic effect of the extracts and ascorbic acid at higher concentrations could be due to the prooxidative tendency of phenolics and antioxidant molecules, including ascorbic acid, at concentrations above a particular threshold. 28,29 Phenolic compounds have been speculated to contribute towards lowering the incidence of neurodegenerative diseases. 30 Of considerable importance to neuronal functions are the acetylcholinesterase and Na + /K + -ATPase enzymes.…”

Section: Discussionmentioning

confidence: 99%

Angiotensin‐1‐converting enzyme inhibition, antioxidant activity, and modulation of cerebral Na+/K+ ATPase by free phenolics of African locust bean (Parkia biglobosa)

Komolafe

Akinmoladun

Komolafe

et al. 2017

Health Science Reports

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Aims: To investigate the antioxidant activities and effects of free phenols (FPPB) and bound phenols (BPPB) of Parkia biglobosa leaves on some enzymes of neuro-cardiovascular relevance.Methods and Results: HPLC-DAD fingerprinting of FPPB and BPPB, and the antihemolytic, radical (1,1-diphenyl-2 picrylhydrazyl, DPPH; 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid), ABTS) scavenging and ferric reducing antioxidant properties of extracts, were assessed. In addition, the effects of the phenolics on angiotensin-1-converting enzyme (ACE), cerebral acetylcholinesterase/butyrylcholinesterase (AChE/BuChE), and Na + /K + ATPase were determined in vitro. FPPB was more potent than BPPB in terms of ABTS (EC 50 :4.06 ± 0.3 vs 24.07 ± 2.1 μg/mL) and DPPH (EC 50 :3.82 ± 0.2 vs 10.22 ± 0.1 μg/mL) radicals scavenged, respectively. The free phenolic extract was a better DPPH . scavenger than ascorbic acid (EC 50 = 12.58 ± 0.4 μg/mL; DPPH reference) and compared well withTrolox (EC 50 :4.44 ± 0.08 μg/mL; ABTS reference). The anti-hemolytic effect of FPPB (36%) and BPPB (53%) was highest at 15 μg/mL but lower than that recorded for ascorbic acid (67% at 10 μg/mL). Even though FPPB (IC 50 = 15.35 ± 4.0 μg/mL) and BPPB (IC 50 = 46.85 ± 3.3 μg/ mL) showed considerably lower ACE-inhibitory effect than ramipril (IC 50 :0.173 ± 0.04 μg/mL), both extracts demonstrated dose-dependent, significant (p < 0.01/p < 0.05) inhibition of the enzyme. FPPB increased cerebral Na+/K+ATPase activity but neither phenolic extract affects cerebral AChE/BuChE activities. HPLC-DAD revealed catechin, caffeic acid, and quercetin, respectively, as the major phenolics (mg/g) in FPPB (29.85, 30.29, and 17.10) and BPPB (32.70, 30.51, and 19.25). Conclusion:The effects of P biglobosa on ACE and cerebral ATPase are related to its constituent phenolics. ACE inhibition could be an important mechanism underlying the documented hypotensive effect of the plant. ----------------------------------------------This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Antioxidant and pro-oxidant activity of Vitamin C in oral environment

Abstract: The data validates the role of Vitamin C as an antioxidant under physiologic conditions exhibiting a cross over role as a pro-oxidant in pathological conditions. Further studies are required to substantiate its pro-oxidant activity to draw concrete conclusions.

Cited by 81 publications

References 0 publications

The enhanced tumor inhibitory effects of gefitinib and L-ascorbic acid combination therapy in non-small cell lung cancer cells

The enhanced tumor inhibitory effects of gefitinib and L-ascorbic acid combination therapy in non-small cell lung cancer cells

COMPOSIÇÃO CENTESIMAL, COMPOSTOS BIOATIVOS E PARÂMETROS FÍSICO-QUÍMICOS DO JENIPAPO (Genipa americana L.) IN NATURA

Angiotensin‐1‐converting enzyme inhibition, antioxidant activity, and modulation of cerebral Na+/K+ ATPase by free phenolics of African locust bean (Parkia biglobosa)

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