A Systematic Study of the Antioxidant Capacity of Humic Substances against Peroxyl Radicals: Relation to Structure

Humic substances (HS) are natural supramolecular systems of high- and low-molecular-weight compounds with distinct immunomodulatory and protective properties. The key beneficial biological activity of HS is their antioxidant activity. However, systematic studies of the antioxidant activity of HS against biologically relevant peroxyl radicals are still scarce. The main objective of this work was to estimate the antioxidant capacity (AOC) of a broad set of HS widely differing in structure using an oxygen radical absorption capacity (ORAC) assay. For this purpose, 25 samples of soil, peat, coal, and aquatic HS and humic-like substances were characterized using elemental analysis and quantitative 13C solution-state NMR. The Folin–Ciocalteu method was used to quantify total phenol (TP) content in HS. The determined AOC values varied in the range of 0.31–2.56 μmol Trolox eqv. mg−1, which is close to the values for ascorbic acid and vitamin E. Forward stepwise regression was used to reveal the four main factors contributing to the AOC value of HS: atomic C/N ratio, content of O-substituted methine and methoxyl groups, and TP. The results obtained clearly demonstrate the dependence of the AOC of HS on both phenolic and non-phenolic moieties in their structure, including carbohydrate fragments.

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Analytical Methods Used in Determining Antioxidant Activity: A Review

International Journal of Molecular Sciences ◽

10.3390/ijms22073380 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3380

Author(s):

Irina Georgiana Munteanu ◽

Constantin Apetrei

Keyword(s):

Antioxidant Activity ◽

Hydrogen Atom ◽

Antioxidant Capacity ◽

Absorption Capacity ◽

Detection Mechanism ◽

Antioxidant Power ◽

Complementary Method ◽

Food Engineering ◽

Advantages And Disadvantages ◽

Major Interest

The study of antioxidants and their implications in various fields, from food engineering to medicine and pharmacy, is of major interest to the scientific community. The present paper is a critical presentation of the most important tests used to determine the antioxidant activity, detection mechanism, applicability, advantages and disadvantages of these methods. Out of the tests based on the transfer of a hydrogen atom, the following were presented: the Oxygen Radical Absorption Capacity (ORAC) test, the Hydroxyl Radical Antioxidant Capacity (HORAC) test, the Total Peroxyl Radical Trapping Antioxidant Parameter (TRAP) test, and the Total Oxyradical Scavenging Capacity (TOSC) test. The tests based on the transfer of one electron include the Cupric Reducing Antioxidant Power (CUPRAC) test, the Ferric Reducing Antioxidant Power (FRAP) test, the Folin–Ciocalteu test. Mixed tests, including the transfer of both a hydrogen atom and an electron, include the 2,2′-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) test, and the [2,2-di(4-tert-octylphenyl)-1 -picrylhydrazyl] (DPPH) test. All these assays are based on chemical reactions and assessing the kinetics or reaching the equilibrium state relies on spectrophotometry, presupposing the occurrence of characteristic colours or the discolouration of the solutions to be analysed, which are processes monitored by specific wavelength adsorption. These assays were successfully applied in antioxidant analysis or the determination of the antioxidant capacity of complex samples. As a complementary method in such studies, one may use methods based on electrochemical (bio)sensors, requiring stages of calibration and validation. The use of chemical methods together with electrochemical methods may result in clarification of the operating mechanisms and kinetics of the processes involving several antioxidants.

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Aldose reductase inhibitory activity and antioxidant capacity of pomegranate extracts

Interdisciplinary Toxicology ◽

10.2478/v10102-012-0003-8 ◽

2012 ◽

Vol 5 (1) ◽

pp. 15-20 ◽

Cited By ~ 22

Author(s):

Çimen Karasu ◽

Ahmet Cumaoğlu ◽

Ali Gúrpinar ◽

Murat Kartal ◽

Lucia Kovacikova ◽

...

Keyword(s):

Antioxidant Activity ◽

Antioxidant Capacity ◽

Aldose Reductase ◽

Diabetic Complications ◽

Inhibitory Activity ◽

Seed Extract ◽

Peroxyl Radicals ◽

Protective Effects ◽

Commercial Sample ◽

Hull Extract

Aldose reductase inhibitory activity and antioxidant capacity of pomegranate extractsThe pomegranate,Punica granatumL., has been the subject of current interest as a medicinal agent with wide-ranging therapeutic indications. In the present study, pomegranate ethanolic seed and hull extracts were tested, in comparison with a commercial sample, for the inhibition of aldose reductase, an enzyme involved in the etiology of diabetic complications. In vitro inhibition of rat lens aldose reductase was determined by a conventional method. Pomegranate ethanolic hull extract and commercial pomegranate hull extract exhibited similar aldose reductase inhibitory activity characterized by IC50values ranging from 3 to 33.3 μg/ml. They were more effective than pomegranate ethanolic seed extract with IC50ranging from 33.3 to 333 μg/ml. Antioxidant action of the novel compounds was documented in a DPPH test and in a liposomal membrane model, oxidatively stressed by peroxyl radicals. All the plant extracts showed considerable antioxidant potential in the DPPH assay. Pomegranate ethanolic hull extract and commercial pomegranate hull extract executed similar protective effects on peroxidatively damaged liposomal membranes characterized by 10 < IC50< 100 μg/ml. Pomegranate ethanolic seed extract showed significantly lower antioxidant activity compared to both hull extracts studied. Pomegranate extracts are thus presented as bifunctional agents combining aldose reductase inhibitory action with antioxidant activity and with potential therapeutic use in prevention of diabetic complications.

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Enhanced Antioxidant Activity of Phycocyanin Oligopeptides

Current Developments in Nutrition ◽

10.1093/cdn/nzab037_046 ◽

2021 ◽

Vol 5 (Supplement_2) ◽

pp. 336-336

Author(s):

James Komorowski ◽

Devon Bernsley ◽

Sarah Sylla ◽

Sara Perez Ojalvo

Keyword(s):

Antioxidant Activity ◽

Singlet Oxygen ◽

Antioxidant Capacity ◽

Peroxyl Radicals ◽

Reference Standard ◽

Blue Green Algae ◽

Optical Absorbance ◽

Funding Sources ◽

Antioxidant Potency ◽

O 24

Abstract Objectives Phycocyanin, a phytonutrient found in blue-green algae, has various beneficial properties, including potent antioxidant effects. The goal of this study was to investigate the antioxidant potency of a novel phycocyanin oligopeptide (PC-O) compared to phycocyanin (PC). Methods Antioxidant potency of PC-O and PC was measured using two different methods: 1) the Folin-Ciocalteu reaction assay, and 2) the Oxygen Radical Absorbance Capacity (ORAC) 6.0 assay. The Folin-Ciocalteu reaction assay (or total phenolics assay) was run using Folin-Ciocalteu's phenol reagent and sodium carbonate. Optical absorbance was measured at 765nm in a colorimetric plate reader with gallic acid as a reference standard. The ORAC 6.0 assay was run to evaluate the antioxidant capacity of a material against six primary reactive oxygen species: peroxyl radical, hydroxyl radical, superoxide anion, singlet oxygen, peroxynitrite, and hypochlorite. Trolox was used as the reference standard, and the results were expressed as μmole Trolox equivalency per gram of a tested material. Results In both assays, PC-O had higher antioxidant potency than PC. In the Folin-Ciocalteu reaction assay, the cellular antioxidant capacity of PC-O (24 mg/L) was greater than PC (16 mg/L). PC-O also demonstrated consistently higher antioxidant activity in the ORAC 6.0 assay, as follows: peroxyl radicals, PC-O (477 μmole TE/gram) vs. PC (26 μmole TE/gram); hydroxyl radicals, PC-O (734 μmole TE/gram) vs. PC (62 μmole TE/gram); peroxynitrite, PC-O (40 μmole TE/gram) vs. PC (7 μmole TE/gram); super oxide anion, PC-O (172 μmole TE/gram) vs. PC (53 μmole TE/gram); singlet oxygen, PC-O (92 μmole TE/gram) vs. PC (70 μmole TE/gram); and hypochlorite, PC-O (2,805 μmole TE/gram) vs. PC (312 μmole TE/gram). Conclusions These results demonstrate that phycocyanin oligopeptide (PC-O) is a superior antioxidant compared to phycocyanin (PC) as shown by its higher cellular antioxidant capacity in the Folin-Ciocalteu reaction assay and significantly higher ORAC 6.0 scores. Funding Sources This work was supported by Nutrition 21, LLC.

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PAOT-Liquid® Technology: An Easy Electrochemical Method for Evaluating Antioxidant Capacity of Wines

Diseases ◽

10.3390/diseases7010010 ◽

2019 ◽

Vol 7 (1) ◽

pp. 10 ◽

Cited By ~ 2

Author(s):

Joël Pincemail ◽

Mouna-Messaouda Kaci ◽

Claire Kevers ◽

Jessica Tabart ◽

Raymond Ebabe Elle ◽

...

Keyword(s):

Antioxidant Activity ◽

Antioxidant Capacity ◽

Total Polyphenols ◽

Polyphenol Compounds ◽

Protective Properties ◽

Commercial Market ◽

Total Antioxidant ◽

Wine Polyphenols ◽

Food Matrices ◽

Highly Correlated

Polyphenol compounds present in high quantity in wines are well-known to have potent cardio-protective properties through several biological mechanisms including antioxidant activity [1]. A large number of methods have been developed for evaluating the antioxidant capacity of food matrices. Most of them have, however, the disadvantage of being time consuming and require specific analytical protocols and devices. In the present study, we present the electrochemical PAOT (Pouvoir Antioxydant Total)-Liquid® Technology which can be easily used by winemakers for evaluating antioxidant activity of wine during all steps of making process. The methodology is based on the measurement of electric potential variation resulting from chemical reactions between wine polyphenols and a free radical mediator M• as source of oxidants. Total antioxidant activity as estimated by the PAOT-Liquid® activity was 6.8 fold higher in red wines (n = 14) when compared to rosé (n = 3) and white (n = 3) wines bought in a commercial market. Moreover, PAOT-Liquid® activity was highly correlated with total polyphenols content (TPC) of all wines (r = 0.9540, p < 0.0001) and the classical DPPH (2,2-diphenyl-1-picryhydrazyl) assay which is often used for evaluating antioxidant capacity of food matrices (r = 0.9102, p < 0.0001).

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EXTRACTION OPTIMIZATION AND ANTIOXIDANT ACTIVITY OF PHENOLIC COMPOUNDS FROM AVOCADO PEEL

Journal of Medicine and Pharmacy ◽

10.34071/mp.2019.3.7 ◽

2019 ◽

pp. 49-59

Author(s):

Nu Linh Giang Ton ◽

Thi Hoai Nguyen ◽

Quoc Hung Vo

Keyword(s):

Antioxidant Activity ◽

Response Surface Methodology ◽

Antioxidant Capacity ◽

Response Surface ◽

Total Antioxidant Capacity ◽

Total Phenolic Content ◽

Phenolic Content ◽

Quadratic Model ◽

Total Phenolic ◽

Total Antioxidant

Avocado peel has been considered as a potential source of natural antioxidants in which phenolics are among the most important compounds. Therefore, this study aims to optimize the extraction process of phenolics using response surface methodology and evaluate the corresponding antioxidant activity. From the quadratic model, the optimal condition was determined including the ethanol concentration 54.55% (v/v), the solvent/solute ratio 71.82/1 (mL/g), temperature 53.03 oC and extraction time 99.09 min. The total phenolic content and the total antioxidant capacity at this condition with minor modifications were 26,74 ± 0,04 (mg GAE/g DW) and 188.06 ± 1.41 (mg AAE/g DW), respectively. The significant correlation between total phenolic content and total antioxidant capacity was also confirmed. Key words: response surface methodology, central composite rotatable design, total phenolic content, total antioxidant capacity, avocado peel

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Synthesis, Cytotoxicity and Antioxidant Activity of New Analogs of RC-121 Synthetic Derivatives of Somatostatin

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520618666180417164344 ◽

2019 ◽

Vol 18 (10) ◽

pp. 1417-1424 ◽

Cited By ~ 2

Author(s):

Emilia Naydenova ◽

Diana Wesselinova ◽

Svetlana Staykova ◽

Ivan Goshev ◽

Ljubomir Vezenkov

Keyword(s):

Antioxidant Activity ◽

Antioxidant Capacity ◽

Cell Line ◽

Cancer Cell ◽

Cancer Cell Line ◽

Colorectal Cancer Cell Line ◽

Cervical Cancer Cell Line ◽

Synthetic Derivatives ◽

Derivatives Of

Background: Based on the structure of RC-121 (D-Phe-c (Cys-Tyr-D-Trp-Lys-Val-Cys)-Thr-NH2, - synthetic derivatives of somatostatin), some analogs were synthesized and tested for in vitro cytotoxic and antioxidant activity. Objectives: The new analogs were modifyed at position 5 with Dap (diaminopropanoic acid), Dab (diaminobutanoic acid) and Orn and at position 6 with the unnatural amino acids Tle (t-leucine). Methods: The in vitro cytotoxic effects of the substances were investigated against a panel of human tumor cell lines HT-29 (Human Colorectal Cancer Cell Line), MDA-MB-23 (Human Breast Cancer Cell Line), Hep G-2 (Human Hepatocellular Carcinoma Cell Line) and HeLa (cervical cancer cell line). The antioxidant capacities were tested by ORAC (Oxygen Radical Antioxidant Capacity) and HORAC (Hydroxyl Radical Averting Capacity) methods. Results: All substances expressed significantly higher antioxidant capacity by comparison with galic acid and Trolox. All substances showed considerable antioxidant capacity as well. Compound 2T (D-Phe-c(Cys-Tyr-DTrp- Dap-Tle-Cys)-Thr-NH2)had the highest antioxidant effect. The compound 4T (D-Phe-c(Cys-Tyr-D-Trp- Orn-Tle-Cys)-Thr-NH2) displayed antiproliferative effect on HeLa cells with IC50 30 µM. The peptide analog 3T (D-Phe-c(Cys-Tyr-D-Trp-Lys-Tle-Cys)-Thr-NH2) exerted the most pronounced inhibition on the cell vitality up to 53%, 56% and 65% resp. against MDA-MB-23, Hep G-2, HeLa in the higher tested concentration. Conclusion: The somatostatin analogs showed moderate influence on the vitality of different tumor cells and could be used in changing their pathology.

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Optimization of Natural Antioxidants Extraction from Pineapple Peel and Their Stabilization by Spray Drying

Foods ◽

10.3390/foods10061255 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1255

Author(s):

Sofia C. Lourenço ◽

Débora A. Campos ◽

Ricardo Gómez-García ◽

Manuela Pintado ◽

M. Conceição Oliveira ◽

...

Keyword(s):

Antioxidant Activity ◽

Antioxidant Capacity ◽

Spray Drying ◽

Total Phenolic Content ◽

Phenolic Content ◽

Food Products ◽

Total Phenolic ◽

Dry Extract ◽

Pineapple Peel ◽

Dpph Method

Pineapple peel still contains an important amount of phenolic compounds and vitamins with valuable antioxidant activity. In this way, the aim of this study was the recovery of the bioactive compounds from pineapple peel using environmentally friendly and low-cost techniques, envisaging their application in food products. From the solid-liquid extraction conditions tested, the one delivering an extract with higher total phenolic content and antioxidant capacity was a single extraction step with a solvent-pineapple peel ratio of 1:1 (w/w) for 25 min at ambient temperature, using ethanol-water (80–20%) as a solvent. The resulting extract revealed a total phenolic content value of 11.10 ± 0.01 mg gallic acid equivalent (GAE)/g dry extract, antioxidant activity of 91.79 ± 1.98 µmol Trolox/g dry extract by the DPPH method, and 174.50 ± 9.98 µmol Trolox/g dry extract by the FRAP method. The antioxidant rich extract was subjected to stabilization by the spray drying process at 150 °C of inlet air temperature using maltodextrin (5% w/w) as an encapsulating agent. The results showed that the antioxidant capacity of the encapsulated compounds was maintained after encapsulation. The loaded microparticles obtained, which consist of a bioactive powder, present a great potential to be incorporated in food products or to produce bioactive packaging systems.

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The Effects of Bioactive Compounds from Blueberry and Blackcurrant Powder on Oat Bran Pastes: Enhancing In Vitro Antioxidant Activity and Reducing Reactive Oxygen Species in Lipopolysaccharide-Stimulated Raw264.7 Macrophages

Antioxidants ◽

10.3390/antiox10030388 ◽

2021 ◽

Vol 10 (3) ◽

pp. 388

Author(s):

Xiao Dan Hui ◽

Gang Wu ◽

Duo Han ◽

Xi Gong ◽

Xi Yang Wu ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Antioxidant Activity ◽

Phenolic Compounds ◽

Antioxidant Capacity ◽

Bioactive Compounds ◽

Reactive Oxygen ◽

Oxygen Species ◽

Raw264.7 Macrophages ◽

Oat Bran

In this study, blueberry and blackcurrant powder were chosen as the phenolic-rich enrichments for oat bran. A Rapid Visco Analyser was used to form blueberry and blackcurrant enriched oat pastes. An in vitro digestion process evaluated the changes of phenolic compounds and the in vitro antioxidant potential of extracts of pastes. The anthocyanidin profiles in the extracts were characterised by the pH differential method. The results showed that blueberry and blackcurrant powder significantly increased the content of phenolic compounds and the in vitro antioxidant capacity of pastes, while the total flavonoid content decreased after digestion compared to the undigested samples. Strong correlations between these bioactive compounds and antioxidant values were observed. Lipopolysaccharide-stimulated RAW264.7 macrophages were used to investigate the intracellular antioxidant activity of the extracts from the digested oat bran paste with 25% enrichment of blueberry or blackcurrant powder. The results indicated that the extracts of digested pastes prevented the macrophages from experiencing lipopolysaccharide (LPS)-stimulated intracellular reactive oxygen species accumulation, mainly by the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signalling pathway. These findings suggest that the bioactive ingredients from blueberry and blackcurrant powder enhanced the in vitro and intracellular antioxidant capacity of oat bran pastes, and these enriched pastes have the potential to be utilised in the development of the functional foods.

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Increase in the antioxidant content in biscuits by infusions or Prosopis chilensis pod flour

Open Agriculture ◽

10.1515/opag-2021-0016 ◽

2021 ◽

Vol 6 (1) ◽

pp. 243-253

Author(s):

Paula Andrea Conforti ◽

Mariela Patrignani

Keyword(s):

Antioxidant Activity ◽

Antioxidant Capacity ◽

Fracture Stress ◽

Fracture Strain ◽

Gluten Free ◽

Maize Starch ◽

Prosopis Chilensis ◽

Antioxidant Content ◽

Fat Level ◽

Increasing Demand

Abstract Nowadays there is an increasing demand for healthy biscuits. The reduction in sugar and fat level, as well as the addition of bioactive compounds, is positively associated with a healthy diet. In the present work, low-fat and low-sugar biscuits were prepared with infusions (mate, coffee, and tea) or with Prosopis chilensis pod flour (PPF). Biscuits were made with maize starch and wheat flour (gluten formulations) or with gluten-free ingredients (gluten-free). The colour, texture, and the antioxidant capacity were evaluated in dough and biscuits. Among the formulations prepared with infusions, the mate dough showed the lowest firmness (1.1 N (gluten)-24.3 N (gluten-free)). However, no significant differences were found in the fracture stress of the final products (P > 0.05). Mate gluten biscuits and PPF gluten-free biscuits showed the highest fracture strain (16.2 and 9.4%, respectively) and the lowest Young’s modulus (7.3 and 13.3 MPa, respectively) in their groups. The highest antioxidant activity was found in biscuits with mate (8.7 µmol FeSO4/g (gluten)-4.3 µmol FeSO4/g (gluten-free)). These values were three times higher than the ones found in the control biscuits (2.9 µmol FeSO4/g (gluten)-3.9 µmol FeSO4/g (gluten-free)). The present results showed that the antioxidant content in biscuits could be successfully increased with infusion addition.

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