Antioxidant and pro-oxidant activity of ascorbic and humic acids in radical-chain oxidation processes

Smirnova, O.V.; Efimova, I. V.; Khil’ko, S. L.

doi:10.1134/s1070427212020164

Cited by 11 publications

(12 citation statements)

References 7 publications

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“…On the other hand, the number of quinoid moieties account for only part of the HA structural fragments involved in electron transfer. Apart from quinoid/semiquinoid moieties, phenolic groups oxidized to phenoxyl radicals can also contribute to antioxidant activity of HAs [ 33 , 59 ]. The EPR and chemical titration analyses show that higher amounts of PMC and phenolic OH groups in the HA structure improves antioxidant activity, with significant coefficients of linear correlation r = 0.60 ( p < 0.01) and r = 0.84 ( p < 0.001), respectively ( Figure 6 ).…”

Section: Resultsmentioning

confidence: 99%

“…Although antiradical and antioxidant activities of some native humic substances have been reported previously [ 28 , 32 , 33 , 34 ], there is no information regarding specific HAs isolated from peat. Because peat could represent an important source of HAs for the pharmaceutical industry, characterization and standardization of their physical and chemical parameters is necessary [ 35 ], especially since no clear relationships have been reported between the pharmacological activities of peat-derived HAs and their humification degree, molecular size distribution, or stable-free radical content [ 36 ].…”

Section: Introductionmentioning

confidence: 99%

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Physicochemical Characterization and Antioxidant Activity of Humic Acids Isolated from Peat of Various Origins

et al. 2018

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Although humic acids (HAs) from peat exhibit various therapeutic properties, there is little information available concerning their physicochemical and antioxidant properties. To address this issue, nine different types of peat, including oligotrophic, mesotrophic, and minerotrophic peat samples, were used for isolation of HA fractions by basic (HAb) and pyrophosphate (HAp) extractions. Physical parameters of the HAs were analyzed by UV-Vis, fluorescent, infrared (IR), and electron paramagnetic resonance (EPR) spectroscopy. Average Mr of the fractions ranged from 17.2 to 39.7 kDa, while their humification index (HIX) varied from 0.49 to 1.21. HAp fractions had a higher content of aromatic structures compared to HAb fractions. Moreover, HAp fractions had a significantly higher content of phenolic OH groups (3.6 ± 0.5 mmol/g) versus HAb (3.1 ± 0.5 mmol/g). All HA fractions exhibited antioxidant activity in radical scavenging and electrochemical assays, and their EPR signal had a single line with g = 2.0035, which is consistent with semiquinone type radicals. Furthermore, the HIX was found to be important in determining the number of semiquinone-type free radicals in the HA structures. Overall, these data provide a molecular basis to explain at least part of the beneficial therapeutic properties of peat-derived HAs.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physicochemical Characterization and Antioxidant Activity of Humic Acids Isolated from Peat of Various Origins

et al. 2018

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“…Recent literature reports reveal that plant-based natural compounds of Brassica oleracea L. var. sabauda [47], red fruits teas [48], Salicornia herbacea L. [49], vegetables and agricultural by-products [50], ascorbic and humic acids [51], Raphanus sativus var. niger [52], green tea [53], and eugenol [54] display both antioxidant and prooxidant behaviours under certain circumstances.…”

Section: Introductionmentioning

confidence: 99%

Secondary Metabolites Profiling of Acinetobacter baumannii Associated with Chili (Capsicum annuum L.) Leaves and Concentration Dependent Antioxidant and Prooxidant Properties

Monowar

Rahman²,

Bhore

et al. 2019

BioMed Research International

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Secondary bioactive compounds of endophytes are inevitable biomolecules of therapeutical importance. In the present study, secondary metabolites profiling of an endophytic bacterial strain, Acinetobacter baumannii, were explored using GC-MS study. Presence of antioxidant substances and antioxidant properties in chloroform (CHL), diethyl ether (DEE), and ethyl acetate (EA) crude extracts of the endophytic bacteria were studied. Total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and ferrous ion chelating assay were evaluated. A total of 74 compounds were identified from the GC-MS analysis of the EA extract representing mostly alkane compounds followed by phenols, carboxylic acids, aromatic heterocyclic compounds, ketones, aromatic esters, aromatic benzenes, and alkenes. Among the two phenolic compounds, namely, phenol, 2,4-bis(1,1-dimethylethyl)- and phenol, 3,5-bis(1,1-dimethylethyl)-, the former was found in abundance (11.56%) while the latter was found in smaller quantity (0.14%). Moreover, the endophytic bacteria was found to possess a number of metal ions including Fe(II) and Cu(II) as 1307.13 ± 2.35 ppb and 42.38 ± 0.352 ppb, respectively. The extracts exhibited concentration dependent antioxidant and prooxidant properties at high and low concentrations, respectively. The presence of phenolic compounds and metal ions was believed to play an important role in the antioxidant and prooxidant potentials of the extracts. Further studies are suggested for exploring the untapped resource of endophytic bacteria for the development of novel therapeutic agents.

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“…This evaluation requires the simultaneous detection and assay of all coexisting antioxidant species, as well as the determination of their kinetic properties. Concerning the former two application fields, ascorbic (AA) and uric (UA) acids represent the major hydrophilic antioxidants not only because they are the highest concentrated compounds in several human biological fluids (serum, urine, tears, cerebrospinal fluid) but also due to their intrinsic antioxidant properties . Both AA and UA are therefore considered as relevant biochemical markers in many pathologies (neonatal hypoxia and coronary heart diseases, amid several others) in which oxidative stress is involved .…”

Section: Introductionmentioning

confidence: 99%

New Insight into the EC’ Mechanism of Uric Acid Regeneration in the Presence of Ascorbic Acid on a Poly(3,4‐ethylenedioxithiophene) Modified Gold Electrode

et al. 2018

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A gold electrode surface was functionalized by means of an electropolymerized conductive poly(3,4‐ethylenedioxythiophene) (PEDOT) organic layer. This modified electrode was used for the electrochemical detection of ascorbic (AA) and uric (UA) acids in an aqueous mixture with a selectivity around 340 mV. The electrochemical reactions kinetics were limited by AA diffusion and UA adsorption at the electrode surface, respectively. Following a previous study ([Electrochem Comm. 2011, 13, 423–425]) cyclic voltammetry was used to provide a better understanding of the EC’ mechanism of regeneration of UA by AA. Experiments particularly showed that allantoin (i. e. the final product of UA oxidation) is not actually involved in the synergic mechanism but rather the oxidized UA product diimine which is adsorbed at the electrode surface.

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Antioxidant and pro-oxidant activity of ascorbic and humic acids in radical-chain oxidation processes

Cited by 11 publications

References 7 publications

Physicochemical Characterization and Antioxidant Activity of Humic Acids Isolated from Peat of Various Origins

Physicochemical Characterization and Antioxidant Activity of Humic Acids Isolated from Peat of Various Origins

Secondary Metabolites Profiling of Acinetobacter baumannii Associated with Chili (Capsicum annuum L.) Leaves and Concentration Dependent Antioxidant and Prooxidant Properties

New Insight into the EC’ Mechanism of Uric Acid Regeneration in the Presence of Ascorbic Acid on a Poly(3,4‐ethylenedioxithiophene) Modified Gold Electrode

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