scholarly journals AN EXPERIMENTAL AND THEORETICAL STUDY OF THE REACTIVITY OF SELECTED CATECHOLAMINES AND THEIR PRECURSORS TOWARDS ASCORBYL RADICAL

2020 ◽  
pp. 1-12
Author(s):  
Dušan Dimić ◽  
Đura Nakarada ◽  
Miloš Mojović ◽  
Jasmina Dimitrić Marković
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Structural Parameters ◽  
Hydrogen Atom Transfer ◽  
Human Organism ◽  
Vanillylmandelic Acid ◽  
Dft Methods ◽  
Ascorbyl Radical ◽  
The Stability ◽  
First Time

Ascorbyl radical is often used as a biomarker of oxidative stress in human organism. It is a product of the antioxidant activity of ascorbic acid and it is not expected to react further with biologically important molecules. For the first time, the reactivity of catecholamines and their precursors was investigated theoretically and experimentally towards ascorbyl radical and the main structural parameters governing activity were analyzed. It was shown that catechol moiety plays an important role, which classifies norepinephrine and 3,4-dihydroxyphenylacetic acid as the most reactive when compared to homovanillic acid, vanillylmandelic acid, and octopamine. DFT methods have been employed to determine the most probable mechanism of the reaction. Based on the change in reaction enthalpy it was concluded that Hydrogen Atom Transfer (HAT) is a preferred mechanism both in water and pentyl ethanoate. The stabilization interactions in ascorbic acid, its anion and radical are carefully analyzed in order to understand the preferability of the mentioned mechanism. The stability of the ascorbyl radical is explained in detail. The results prove that ascorbyl radical is not just a product of antioxidant activity, but also a potentially harmful species in an organism.

scholarly journals Complexes of Copper and Iron with Pyridoxamine, Ascorbic Acid, and a Model Amadori Compound: Exploring Pyridoxamine’s Secondary Antioxidant Activity

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 208
Author(s):  
Guillermo García-Díez ◽  
Roger Monreal-Corona ◽  
Nelaine Mora-Diez
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Rate Constant ◽  
Stable Complex ◽  
Aqueous Environment ◽  
Oh Radicals ◽  
Bidentate Ligands ◽  
Superoxide Radical Anion ◽  
Amadori Compound ◽  
The Stability

The thermodynamic stability of 11 complexes of Cu(II) and 26 complexes of Fe(III) is studied, comprising the ligands pyridoxamine (PM), ascorbic acid (ASC), and a model Amadori compound (AMD). In addition, the secondary antioxidant activity of PM is analyzed when chelating both Cu(II) and Fe(III), relative to the rate constant of the first step of the Haber-Weiss cycle, in the presence of the superoxide radical anion (O2•−) or ascorbate (ASC−). Calculations are performed at the M05(SMD)/6-311+G(d,p) level of theory. The aqueous environment is modeled by making use of the SMD solvation method in all calculations. This level of theory accurately reproduces the experimental data available. When put in perspective with the stability of various complexes of aminoguanidine (AG) (which we have previously studied), the following stability trends can be found for the Cu(II) and Fe(III) complexes, respectively: ASC < AG < AMD < PM and AG < ASC < AMD < PM. The most stable complex of Cu(II) with PM (with two bidentate ligands) presents a ΔGf0 value of −35.8 kcal/mol, whereas the Fe(III) complex with the highest stability (with three bidentate ligands) possesses a ΔGf0 of −58.9 kcal/mol. These complexes can significantly reduce the rate constant of the first step of the Haber-Weiss cycle with both O2•− and ASC−. In the case of the copper-containing reaction, the rates are reduced up to 9.70 × 103 and 4.09 × 1013 times, respectively. With iron, the rates become 1.78 × 103 and 4.45 × 1015 times smaller, respectively. Thus, PM presents significant secondary antioxidant activity since it is able to inhibit the production of ·OH radicals. This work concludes a series of studies on secondary antioxidant activity and allows potentially new glycation inhibitors to be investigated and compared relative to both PM and AG.

scholarly journals The Antioxidant and Antiproliferative Activities of 1,2,3-Triazolyl-L-Ascorbic Acid Derivatives

2019 ◽  
Vol 20 (19) ◽  
pp. 4735 ◽  
Author(s):  
Anja Harej ◽  
Andrijana Meščić Macan ◽  
Višnja Stepanić ◽  
Marko Klobučar ◽  
Krešimir Pavelić ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Breast Adenocarcinoma ◽  
Scavenging Activity ◽  
Activity Data ◽  
Oh Groups ◽  
Mcf 7

The novel 4-substituted 1,2,3-triazole L-ascorbic acid (L-ASA) conjugates with hydroxyethylene spacer as well as their conformationally restricted 4,5-unsaturated analogues were synthesized as potential antioxidant and antiproliferative agents. An evaluation of the antioxidant activity of novel compounds showed that the majority of the 4,5-unsaturated L-ASA derivatives showed a better antioxidant activity compared to their saturated counterparts. m-Hydroxyphenyl (7j), p-pentylphenyl (7k) and 2-hydroxyethyl (7q) substituted 4,5-unsaturated 1,2,3-triazole L-ASA derivatives exhibited very efficient and rapid (within 5 min) 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging activity (7j, 7k: IC50 = 0.06 mM; 7q: IC50 = 0.07 mM). In vitro scavenging activity data were supported by in silico quantum-chemical modelling. Thermodynamic parameters for hydrogen-atom transfer and electron-transfer radical scavenging pathways of anions deprotonated at C2-OH or C3-OH groups of L-ASA fragments were calculated. The structure activity analysis (SAR) through principal component analysis indicated radical scavenging activity by the participation of OH group with favorable reaction parameters: the C3-OH group of saturated C4-C5(OH) derivatives and the C2-OH group of their unsaturated C4=C5 analogues. The antiproliferative evaluation showed that p-bromophenyl (4e: IC50 = 6.72 μM) and p-pentylphenyl-substituted 1,2,3-triazole L-ASA conjugate (4k: IC50 = 26.91 μM) had a selective cytotoxic effect on breast adenocarcinoma MCF-7 cells. Moreover, compound 4e did not inhibit the growth of foreskin fibroblasts (IC50 > 100 μM). In MCF-7 cells treated with 4e, a significant increase of hydroxylated hypoxia-inducible transcription factor 1 alpha (HIF-1α) expression and decreased expression of nitric oxide synthase 2 (NOS2) were observed, suggesting the involvement of 4e in the HIF-1α signaling pathway for its strong growth-inhibition effect on MCF-7 cells.

scholarly journals Antioxidant potential study of some synthesized N-heterocycles

2009 ◽  
Vol 35 (2) ◽  
pp. 49-52 ◽  
Author(s):  
Mohammad Mamun Hossain ◽  
Sukanta Kumar Shaha ◽  
Foysal Aziz
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Anticancer Activity ◽  
Heterocyclic Compounds ◽  
Antioxidant Properties ◽  
Biological Properties ◽  
Antioxidant Potential ◽  
Heating Method ◽  
Dpph Method ◽  
First Time

Nitrogen containing heterocyclic compounds such as oxindoles especially isatins and their derivatives have excellent biological properties such as anti-inflammatory, antimicrobial, anticancer activity. In addition, this is first time ever we would like to report the antioxidant properties of the said class of compounds. To determine such an important bioactivity a number of halogenated oxindoles 1-3, their diaza-biphenyl derivatives (4-6), ring extended biphenyl (7) and bis-amide (8) were synthesized by classical heating method. The antioxidant activity of all the synthesized compounds was screened by DPPH method with respect to ascorbic acid. In our present investigation some of the synthesized compounds (1, 2, 3, 5 and 6) were found to be active.Keywords: Antioxidant; Isatin; OxindoleOnline 12 August 2009DOI: 10.3329/bmrcb.v35i2.2564Bangladesh Med Res Counc Bull 2009; 35: 49-52 

scholarly journals Strawberry Puree Functionalized with Natural Hydroxytyrosol: Effects on Vitamin C and Antioxidant Activity

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5829
Author(s):  
Alejandra Bermúdez-Oria ◽  
Yougourthane Bouchal ◽  
África Fernández-Prior ◽  
Blanca Vioque ◽  
Juan Fernández-Bolaños
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Vitamin C ◽  
Functional Food ◽  
Dehydroascorbic Acid ◽  
Model System ◽  
Human Diet ◽  
Low Concentrations ◽  
High Concentrations ◽  
The Stability

The natural antioxidant hydroxytyrosol (HT) was used to functionalize a strawberry puree. The effect of the antioxidant on the stability of the two bioactive forms of vitamin C (ascorbic acid-AA and dehydroascorbic acid-DHAA) in strawberry puree stored at 4 °C, compared with the effect on a model system of AA in water, was investigated. In the absence of HT, the concentration of vitamin C in strawberry puree decreased but not in the model system. Low concentrations of HT in strawberry puree (0.05 and 0.1 mg HT/g puree) stabilized vitamin C and improved its antioxidant activity. However, at high concentrations of HT (from 0.5 mg HT/g puree), although the antioxidant activity improved, degradation of vitamin C occurred. Therefore, the concentration of HT used to obtain a functionalized strawberry puree it is very important. An adequate concentration increases the antioxidant activity and protects vitamin C from degradation, developing a functional food. However, an inadequate concentration of HT affects the vitamin C content, which is essential for the human diet because it cannot be biosynthetized by the organism.

scholarly journals Polyphenols, L-Ascorbic Acid, and Antioxidant Activity in Wines from Rose Fruits (Rosa rugosa)

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2561
Author(s):  
Andrzej Cendrowski ◽  
Marcin Królak ◽  
Stanisław Kalisz
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Phenolic Compounds ◽  
Antioxidant Capacity ◽  
Quality Characteristics ◽  
Raw Material ◽  
Rosa Rugosa ◽  
Fruit Wine ◽  
High Antioxidant Activity ◽  
The Stability

The aim of the present study was to determine the influence of the winemaking process on the antioxidant potential and content of phenolic compounds and L-ascorbic acid in wines from the fruits of Rosa rugosa. The results obtained in this study clearly indicate that the fruits of the Rosa rugosa are a desirable raw material for the production of fruit wine. The parameters of the technological process of producing wines from rose fruits had a diversified influence on the tested quality characteristics. Aged wines contained phenolics levels of 473–958 mg/100 mL GAE. The final concentrations of ascorbic acid ranged from 61 to 155 mg/100 mL for the different variants of the wine. Wines revealed high antioxidant activity in assay with DPPH. On the basis of the obtained results, it can be assumed that all the applied variants of the winemaking process are suitable for rose fruit wine. Each variant ensured at least the stability of the antioxidant capacity.

scholarly journals Antioxidant and Antibacterial Constituents from Two Sumatran Ferns, Trichomanes javanicum and Oleandra pistillaris

2017 ◽  
Vol 12 (8) ◽  
pp. 1934578X1701200
Author(s):  
Nofrizal ◽  
Deddi P. Putra ◽  
Dayar Arbain
Keyword(s):  
Staphylococcus Aureus ◽  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Bacillus Subtilis ◽  
Enterococcus Faecalis ◽  
Spectroscopic Methods ◽  
Dihydroxybenzoic Acid ◽  
Aerial Parts ◽  
Stems And Leaves ◽  
First Time

Mangiferin (1), vitexin (2) and 4- O-β-D-glucopyranosylcaffeic acid (3), by means of classical extraction, fractionation and chromatographic separation, have been isolated for the first time from aerial parts (stems and leaves) of Trichomanes javanicum Blume (Hymenophyllaceae) as well as 3,4-dihydroxybenzoic acid (4) and gallic acid (5) from the rhizome of Oleandra pistillaris (Sw.) C. Chr. (Oleandraceae). These compounds were characterized by spectroscopic methods and then compared to those of data reported in the literature. Compound (1) and (4) showed significant antioxidant activity (IC50 value was 3.89 and 3.83 μM respectively) twice stronger than ascorbic acid as standard (IC50 value 7.86 μM). Compound (4) and (5) significantly inhibited the growth of Salmonella thypimurium and S. thypi while compounds (1), (2) and (3) showed weak inhibition toward Staphylococcus aureus, Bacillus subtilis and Vibrio cholerae. All compounds were not active against Enterococcus faecalis and Streptococcus mutans.

The Structural, Electronic and Optical Properties of Hydrofluorinated Germanene (GeH1-xFx): A First-Principles Study

2021 ◽  
Author(s):  
V Kumar ◽  
R Santosh ◽  
Anita Sinha ◽  
J Kumar
Keyword(s):  
Heat Capacity ◽  
Optical Properties ◽  
Binding Energy ◽  
First Principles ◽  
Structural Parameters ◽  
Plasmon Energy ◽  
Electronic And Optical Properties ◽  
Energy Bandgap ◽  
The Stability ◽  
First Time

Abstract The structural, electronic, and optical properties of hydrofluorinated germanene have been studied with different occupancy ratios of fluorine and hydrogen. The hybridization of H-1s and Ge-4p orbitals in hydrogenated germanene and F-2p and Ge-4p orbitals in fluorinated germanene plays a significant role in creating an energy bandgap. The binding energy and phonon calculations confirm the stability of hydrofluorinated germanene decreases with the increase of the F to H ratio. The value of the energy bandgap decreased by increasing the ratio of F and H. The optical properties have been studied in the energy range of 0-25 eV. Six essential parameters such as energy bandgap (Eg), binding energy (Eb), dielectric constant ε(0), refractive index n(0), plasmon energy (ћωp), and heat capacity (Cp) have been calculated for different occupancies of H and F in hydrofluorinated germanene for the first time. The calculated values of structural parameters agree well with the available experimental and reported values.

scholarly journals In Vitro Antioxidant Capacity of Opuntia spp. Fruits Measured by the LOX-FL Method and its High Sensitivity Towards Betalains

2021 ◽  
Author(s):  
Andrea Gómez-Maqueo ◽  
Mario Soccio ◽  
M. Pilar Cano
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Antioxidant Capacity ◽  
Radical Scavenging ◽  
High Sensitivity ◽  
Biological Mechanisms ◽  
First Time ◽  
Opuntia Spp

AbstractCurrent in vitro methodologies neglect or subestimate the contribution of betalains to antioxidant capacity in foods because they do not reflect their in vivo biological mechanisms. In this study, we assessed the sensibility of the lipoxygenase-fluorescein (LOX-FL) method towards betalains, phenolic compounds and ascorbic acid from Opuntia spp. fruits; and (ii) the antioxidant capacity of peel and pulp extracts from Opuntia ficus-indica L. Mill (var. Fresa, Colorada and Blanco) and Opuntia stricta var. Dillenii; by comparing the LOX-FL method to traditional antioxidant methods (ORAC and TEAC). The spectrophotometric monitoring of the LOX-FL reaction avoided interference caused by betalain pigments. Indicaxanthin and betanin showed high antiperoxidative and radical scavenging mechanisms in the LOX-FL assay. O. stricta var. Dillenii tissues the highest antioxidant capacity which correlated with betanin content. ORAC and TEAC antioxidant methods were less sensible towards betalain antioxidant activity. To our knowledge, this is the first time the LOX-FL antioxidant method has been used on betalains and betalain-rich foods. Graphical Abstract

scholarly journals Antioxidant activity of acerola extracts

2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S155-S158 ◽  
Author(s):  
I. Nagamine ◽  
H. Sakurai ◽  
H. T T Nguyen ◽  
M. Miyahara ◽  
J. Parkányiová ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Linoleic Acid ◽  
Ferulic Acid ◽  
Phenolic Antioxidants ◽  
Zeroth Order ◽  
The Stability ◽  
In The Beginning ◽  
Β Carotene

West Indian cherries or acerola fruits (Malpighia glabra L.) are very rich in ascorbic acid, and also contain flavonoids and anthocyanins. Therefore, their antioxidant activity is interesting. Aqueous and methanolic acerola extracts increased the stability of β-carotene-linoleic acid emulsions against oxidation. Flavonoids and anthocyanins obviously enhanced the effect of ascorbic acid. The effect of natural acerola antioxidants was comparable to that of phenolic antioxidants, such as ferulic acid. During the determination of antioxidant activity in emulsions, carotene was destroyed following a complex kinetics in the beginning of oxidation, but the zeroth order kinetics in later stages of oxidation.

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

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