Computational Models for the Determination of Antioxidant Capacity and Phenolics in Dietary Supplements Using Real-Time Proton Transfer Kinetics Data

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Sunday O Idowu ◽  
Morenikeji A Adeyemo ◽  
Ademola J Itiola
Keyword(s):  
Free Radical ◽  
Proton Transfer ◽  
Antioxidant Capacity ◽  
Dietary Supplement ◽  
Exponential Decay ◽  
Linear Free Energy Relationship ◽  
Phenol Red ◽  
Kinetic Assay ◽  
Hydroxyl Ion ◽  
Chain Breaking

Hydrogen atom transfer (HAT) underlies free-radical chain-breaking by phenolic compounds. Using linear free energy relationship (LFER) analysis, proton transfer kinetics was hypothesized as a surrogate rate process for HAT. Phenol red is a probe that is easily oxidized to highly absorbing specie by hydroxyl ion. Absorbance decay of oxidized phenol red was induced by incremental proton transfer from a model phenolic (resorcinol). Global best-fit kinetics profile of resorcinol approximates a mono-exponential decay model (R2 = 0.991) as a limiting law. Proton transfer rate constant (Kptt) versus concentration reveal the utility of the slope (?aoc) of the linear plot (r2= 0.990) as a sensitive predictor of phenolic antioxidant capacity. Superior antioxidant capacity profile of a polyphenol-rich dietary supplement: Garcinia kola seed extract, optimally obeyed a mixed linear/mono-exponential decay equation. Model robustness and selectivity for phenolics was achieved by specifying mathematical constraints as acceptance criteria. The method is more biologically relevant for chain-breaking antioxidants than free-radical-based assays because it captures antioxidant structure-function relationships. Further validation studies, using structurally diverse polyphenols, are warranted to ascertain general utility of the kinetic assay for achieving quality by design (QbD) in phenolic dietary supplement products.

Computational Antioxidant Capacity Simulation (CAOCS): A Novel Framework of Antioxidant Capacity Profiling

2014 ◽  
Vol 9 (1) ◽  
pp. 25-43 ◽  
Author(s):  
Sunday O. Idowu
Keyword(s):  
Proton Transfer ◽  
Antioxidant Capacity ◽  
Exponential Decay ◽  
Information Criterion ◽  
Hydrogen Atom Transfer ◽  
Phenol Red ◽  
Linear Free Energy ◽  
Analytical System ◽  
Decay Threshold ◽  
Exponential Decay Equation

Abstract Inconsistent ranking is a well-known drawback of antioxidant capacity (AOC) profiling methodologies that use free-radical species as oxidant. This problem leads to assay results that are not biorelevant. Linear free energy relationships (LFER) theory predicts proton transfer (PT) kinetics as a surrogate for biorelevant hydrogen atom transfer (HAT) kinetics. Computational antioxidant capacity simulation (CAOCS), based on real-time proton transfer kinetics modeling (PTKM) of polyphenols and phenol-like small molecules, inspired a novel AOC profiling methodology. Kinetic data acquired by incremental addition of resorcinol to an oxidized probe (phenol red), was fitted to mono-exponential decay equation (MED). Absorbance decay data from strongly antioxidant phenol-like molecules (e.g. ascorbic acid) and a new chromogenic probe (phenolphthalein) was fitted to MED and bi-exponential decay equation. The preferred model and corresponding best-fit rate constant (Kptt) was identified by comparison of fits, using Akaike’s Information Criterion (AICc). Photometric phenolphthalein assay (PPA)-derived metric was normalized with photometric phenol red assay (PPRA) results by using a function developed from proton concentration differential between phenolphthalein and phenol red, with respect to decay threshold to plateau (assay endpoint) interval. pKa dependence of the CAOCS’ metric is a signature of structure–function relationships, and hence, biorelevance. It is shown, unambiguously, that a combination of two phenolic probe molecules, an analytical system devoid of free radicals, and statistical identification of preferred exponential decay fit to PT kinetics data, constitutes a novel algorithm for AOC profiling of polyphenols and phenol-like molecules. This methodology holds a promise of utility in quality assurance of dietary supplements.

scholarly journals Antioxidant Rich Extracts of Terminalia ferdinandiana Inhibit the Growth of Foodborne Bacteria

Foods ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 281 ◽  
Author(s):  
Saleha Akter ◽  
Michael E. Netzel ◽  
Ujang Tinggi ◽  
Simone A. Osborne ◽  
Mary T. Fletcher ◽  
...  
Keyword(s):  
Free Radical ◽  
Antioxidant Capacity ◽  
Total Phenolic Content ◽  
Phenolic Content ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Food Preservation ◽  
Total Phenolic ◽  
Foodborne Bacteria ◽  
Terminalia Ferdinandiana

Terminalia ferdinandiana (Kakadu plum) is a native Australian plant containing phytochemicals with antioxidant capacity. In the search for alternatives to synthetic preservatives, antioxidants from plants and herbs are increasingly being investigated for the preservation of food. In this study, extracts were prepared from Terminalia ferdinandiana fruit, leaves, seedcoats, and bark using different solvents. Hydrolysable and condensed tannin contents in the extracts were determined, as well as antioxidant capacity, by measuring the total phenolic content (TPC) and free radical scavenging activity using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. Total phenolic content was higher in the fruits and barks with methanol extracts, containing the highest TPC, hydrolysable tannins, and DPPH-free radical scavenging capacity (12.2 ± 2.8 g/100 g dry weight (DW), 55 ± 2 mg/100 g DW, and 93% respectively). Saponins and condensed tannins were highest in bark extracts (7.0 ± 0.2 and 6.5 ± 0.7 g/100 g DW). The antimicrobial activity of extracts from fruit and leaves showed larger zones of inhibition, compared to seedcoats and barks, against the foodborne bacteria Listeria monocytogenes, Bacillus cereus, Methicillin resistant Staphylococcus aureus, and clinical isolates of Pseudomonas aeruginosa. The minimum inhibitory concentration and minimum bactericidal concentration in response to the different extracts ranged from 1.0 to 3.0 mg/mL. Scanning electron microscopy images of the treated bacteria showed morphological changes, leading to cell death. These results suggest that antioxidant rich extracts of Terminalia ferdinandiana fruits and leaves have potential applications as natural antimicrobials in food preservation.

Antioxidant Capacities of Water-Soluble Substances Extracted from JinHua Ham

2014 ◽  
Vol 675-677 ◽  
pp. 1654-1657
Author(s):  
Xiao Li Zhou ◽  
Xu Chen ◽  
Ting Feng Hao ◽  
Yi Ming Zhou ◽  
Ying Xiao
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Antioxidant Capacity ◽  
Mass Fraction ◽  
Water Soluble ◽  
Oxidation Capacity ◽  
Hydroxyl Free Radical ◽  
Antioxidant Capacities ◽  
Dpph Scavenging ◽  
Jinhua Ham

This study was designed to evaluate the antioxidant activity of samples extracted from Jinhua ham by using such chemical assays as DPPH, scavenging hydroxyl free radical and ABTS. The results demonstrate that antioxidant capacity of the extracted sample is lower than oxidation capacity of Vc. The IC50 spot of samples ranges between 0.6 % and 2.5 % (mass fraction of solute).

scholarly journals Effects of Fruit Maturity on Physicochemical Properties, Sugar Accumulation and Antioxidant Capacity of Wild Harvested Kakadu Plum (Terminalia ferdinandiana)

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 48
Author(s):  
Anh Dao Thi Phan ◽  
Maral Seidi Damyeh ◽  
Saleha Akter ◽  
Mridusmita Chaliha ◽  
Michael E. Netzel ◽  
...  
Keyword(s):  
Free Radical ◽  
Antioxidant Capacity ◽  
Soluble Sugars ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Maturity Stages ◽  
Radical Scavenging Capacity ◽  
Scavenging Capacity ◽  
Kakadu Plum ◽  
Terminalia Ferdinandiana

Terminalia ferdinandiana (Kakadu plum), belonging to the family Combretaceae, is endemic to Australia and has a long history of traditional medicinal applications and food cuisine by the Australian Indigenous people. This study investigated the effects of maturity stages on the morphology, physicochemical parameters (total soluble solids (TSS), total acid content (TAC), and pH), soluble sugar profile and antioxidant capacity of Kakadu plum (KP) fruits that were wild harvested from different trees and classified into four different maturity stages (immature to mature). TSS and TAC were determined by standard assays/procedures, main sugars by UHPLC–MS/MS and antioxidant capacity (total phenolic content (TPC) and DPPH free radical scavenging capacity) by spectrophotometry. The results showed that soluble sugars (glucose, sucrose and fructose) ranging from 1.3 to 17.7% dry weight (DW), TSS (17.0–52.7% DW) and TAC (1.3–6.7% DW) increased with maturity. However, antioxidant capacity (TPC in the range of 7.4–21.9% DW and DPPH free radical scavenging capacity from 22 to 76% inhibition at the extract concentration of 20 g·L−1) did not follow the same trend as the one observed for soluble sugars, TSS and TAC. These differences were associated with the tree-to-tree variability as a consequence of the wild harvest condition. This study provides important information to both the KP industry and Indigenous enterprises regarding the selection of the appropriate maturity stage to harvest KP fruit to target for different markets (e.g., low-sugar vs. high-sugar fruit).

scholarly journals Influence of phenolic acid content on the antioxidant capacity of hemicellulose from sorghum plant fractions

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 7933-7953
Author(s):  
Ryan J. Stoklosa ◽  
Renee J. Latona ◽  
Michael J. Powell ◽  
Madhav P. Yadav
Keyword(s):  
Free Radical ◽  
Antioxidant Capacity ◽  
Radical Scavenging ◽  
Free Radical Scavengers ◽  
Process Economics ◽  
Scavenging Effect ◽  
Sorghum Bran ◽  
Sorghum Bagasse ◽  
Sorghum Plant ◽  
Methoxy Content

Recovered hemicellulose fractions from biorefineries have the potential to improve overall process economics during the production of biofuels or other high value chemicals. A common hemicellulose found in many agricultural feedstocks is arabinoxylan (AX). This work investigated the influence of ferulic and p-coumaric acids on the antioxidant capability of AX hemicellulose recovered from sorghum bran, biomass, and bagasse. Sorghum bagasse and sorghum biomass AX contained the largest quantities of bound ferulic and p-coumaric acids at 13.1 mg/100 g and 6.3 mg/100 g, respectively. Antioxidant performance showed that sorghum bagasse AX hemicellulose produced the best reducing capability, while sorghum biomass and sorghum bran AX hemicellulose performed better as free radical scavengers. A reduction in free radical scavenging, as determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, occurred for sorghum bagasse and sorghum biomass AX hemicellulose at higher polysaccharide concentrations, which was either caused by the solution properties of the AX hemicelluloses or DPPH reaction reversibility in the presence of phenolic compounds with methoxy content. Alternatively, H2O2 scavenging by the AX hemicellulose revealed a dose-dependent response. Although scavenging effect was reduced at higher concentrations, sorghum bagasse AX hemicellulose functioned as having the best antioxidant capacity with respect to total reducing capability.

scholarly journals PHYTOCHEMICAL CHARACTERIZATION AND ANTIOXIDANT ACTIVITY OF THE NORTHERN MOROCCAN SPECIES: WITHANIA FRUTESCENS L.

2019 ◽  
pp. 276-279 ◽  
Author(s):  
ABDELFATTAH EL MOUSSAOUI ◽  
FATIMA ZAHRA JAWHARI ◽  
DALILA BOUSTA ◽  
AMINA BARI
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Antioxidant Capacity ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Mineral Elements ◽  
Free Radical Scavenging ◽  
Butylated Hydroxytoluene ◽  
Phytochemical Analysis ◽  
Total Polyphenols

Objective: In this study, we were interested in qualitative, quantitative phytochemical characterization and evaluation of the antioxidant capacity of the total extracts of a plant from northern Morocco, the species selected for this study is Withania frutescens. Materials and Methods: Analysis of mineral elements by inductive coupling plasma-atomic absorption spectroscopy (ICP-AES), phytochemical screening, polyphenol and tannin assays, evaluation of antioxidant activity by the 1,2-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method and reducing power. Results: The plant contains alkaloids, saponins, tannins, mucilages, and coumarins. It has a relatively high content of total polyphenols and tannins of 19.53±0.018 μg genetic generalized epilepsy/mg MS and 6.258±0.062 μg Eqcat/mg MS, respectively. The analysis of mineral elements by ICP-AES shows that our species is rich in mineral elements which are calcium, magnesium, and sodium, and it is devoid of metallic elements such as nickel, lead, cadmium, and cobalt. The evaluation of antioxidant activity by the DPPH free radical scavenging method shows that the half maximal inhibitory concentration of the tested extracts has an antiradical activity of about 0.056±0.008 μg/ml for the ethanol extract and 0.213±0.004 μg/ml for the methanol extract compared to the butylated hydroxytoluene value of 0.009±0.0004 μg/ml which was used as a reference. The reducing capacity test shows that methanolic extract has a high antioxidant capacity (0.213±0.006) compared to ethanolic extract (0.043±0.004) but remains low compared to ascorbic acid (0.003±0.0004) which was used as reference. Conclusion: Phytochemical analysis of W. frutescens shows that this plant is rich in high quantities of alkaloids, saponins, mucilage, tannins, and coumarins. It contains an average amount of total polyphenols and tannins that confer significant antioxidant activity to the plant studied.

Contribution of anthocyanins to the antioxidant capacity of juvenile and senescing sugar maple (Acer saccharum) leaves

2007 ◽  
Vol 34 (8) ◽  
pp. 714 ◽  
Author(s):  
Abby K. van den Berg ◽  
Timothy D. Perkins
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Antioxidant Capacity ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Radical Scavenging ◽  
Anthocyanin Content ◽  
Additional Source ◽  
Stable Free Radical ◽  
Maple Leaves

Foliar anthocyanins are hypothesised to provide an additional source of photoprotection from photooxidative stress to the leaves in which they occur through their ability to scavenge excess free radical species. Although demonstrated to significantly enhance the antioxidant status of red morphs of fully expanded leaves of some species, the contribution of anthocyanins to the antioxidant capacity of the juvenile and senescing leaves in which they frequently occur has not been examined. Antioxidant activity of extracts from anthocyanic and non-anthocyanic juvenile and senescing sugar maple (Acer saccharum Marsh.) leaves from similar light environments was assessed using the stable free radical 1,1-diphenyl-2-picryl hydrazyl (DPPH). Anthocyanin content was significantly correlated with antioxidant activity in extracts of anthocyanic juvenile leaves but only weakly correlated in extracts of anthocyanic senescing leaves. In addition, the antioxidant activity of anthocyanic and non-anthocyanic leaves was equal in both juvenile and senescing leaves. Thus, although anthocyanins may contribute to the antioxidant capacity of anthocyanic juvenile and senescing sugar maple leaves, these results are not consistent with the hypothesis that anthocyanins provide an enhancement to the photoprotection available in either leaf type through free radical scavenging. The results suggest anthocyanins may be part of alternative strategies employed by anthocyanic juvenile and senescing maple leaves to achieve similar levels of antioxidant capacity as their non-anthocyanic counterparts to cope with the same set of environmental challenges.

scholarly journals SALT ERROR OF INDICATORS DUE TO STANDARD ALKALINE BUFFERS THEMSELVES. II

1929 ◽  
Vol 12 (5) ◽  
pp. 695-710 ◽  
Author(s):  
J. W. McBain ◽  
M. E. Laing ◽  
O. E. Clark
Keyword(s):  
Sodium Hydroxide ◽  
Aqueous Sodium Hydroxide ◽  
Thymol Blue ◽  
Phenol Red ◽  
Dilute Solutions ◽  
Aqueous Sodium ◽  
Previous Communication ◽  
Alizarin Yellow ◽  
Hydroxyl Ion

Previous results of the comparison of colors given by indicators in alkaline buffers and pure aqueous sodium hydroxide have been repeated and confirmed. The electrometric determinations show that the sodium hydroxide was pure and gave theoretical values for the concentration of hydroxyl ion. The slight but distinct neutralising effect of dilute solutions of alkali has been measured electrometrically and the allowances to be made are recorded graphically. It is found that whereas alizarin yellow G, tropæolin O and thymol violet may be used without appreciable error (in accordance with our previous communication) the grave discrepancies remain for phenolphthalein, o-cresol phthalein and thymol blue and phenol red which must be ascribed to salt error in the alkaline buffer itself.

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