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A Novel Stoichio-Kinetic Model for the DPPH• Assay: The Importance of the Side Reaction and Application to Complex Mixtures. Antioxidants (Basel) 2021; 10:antiox10071019. [PMID: 34202778 PMCID: PMC8300744 DOI: 10.3390/antiox10071019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/15/2021] [Accepted: 06/22/2021] [Indexed: 12/26/2022] Open
Abstract
The 2,2-diphenyl-1-picrylhydrazyl (DPPH•) assay is widely used to determine the antioxidant activity of food products and extracts. However, the common DPPH• protocol uses a two-point measurement and does not give information about the kinetics of the reaction. A novel stoichio-kinetic model applied in this study monitors the consumption of DPPH• by common antioxidants following the second order reaction. The fitting of such decay yields the rate constant k1, which describes the main reaction between antioxidants and DPPH•, and the rate constant k2, which is attributed to a slower side reaction considering the products generated between the transient radicals (AO•) and another molecule of DPPH•. The model was first applied to antioxidant standards. Sinapic acid, Trolox and ascorbic and chlorogenic acids did not show any side reaction. Instead gallic, ferulic and caffeic acids achieved the best fitting with k2. The products of the side reaction for these compounds were confirmed and identified with high-resolution mass spectrometry. Finally, the kinetic model was applied to evaluate the antioxidant activity of eight herbal extracts. This study suggests a new kinetic approach to standardize the common DPPH• assay for the determination of antioxidant activity.
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Yang H, Xue X, Li H, Apandi SN, Tay-Chan SC, Ong SP, Tian EF. The relative antioxidant activity and steric structure of green tea catechins – A kinetic approach. Food Chem 2018; 257:399-405. [DOI: 10.1016/j.foodchem.2018.03.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 02/28/2018] [Accepted: 03/11/2018] [Indexed: 12/19/2022]
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Ye Y, Ji J, Pi F, Yang H, Liu J, Zhang Y, Xia S, Wang J, Xu D, Sun X. A novel electrochemical biosensor for antioxidant evaluation of phloretin based on cell-alginate/ʟ-cysteine/gold nanoparticle-modified glassy carbon electrode. Biosens Bioelectron 2018; 119:119-125. [PMID: 30121423 DOI: 10.1016/j.bios.2018.07.051] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/19/2018] [Accepted: 07/25/2018] [Indexed: 11/28/2022]
Abstract
Antioxidant evaluation of bioactive compounds is limited, since many methods lack a real physiological environment that can be used conveniently and intuitively. In this study, a simple, label-free and effective electrochemical biosensor method has been developed to evaluate the antioxidant effect of phloretin (Ph) by 3D cell modification on a glassy carbon electrode (GCE). In response to this, A549 cells were immobilized onto a self-assembled ʟ-cysteine/gold nanoparticle (AuNPs/ʟ-Cys)-modified GCE surface by a simple drop casting after encapsulated in alginate. The electrochemical impedance spectroscopy (EIS) results showed that the impedance value (Ret) increased with the concentration of H2O2 in the range of 0-60 μmol/L with the correlation of 0.990 which acted as an oxidative stress model inducer. However, the EIS value decreased with the co-incubation of Ph ranging from 10 to 100 μmol/L, showing a dose-dependent manner and time effect, indicating that the variation of Ret was responded to the antioxidant effect. The response impedance of the biosensor is linear to Ph concentrations from 20 μmol/L to 100 μmol/L with the detection limit (LOD) as 1.96 μmol/L. A significant correlation was observed between reactive oxygen species (ROS) values and Ret values following the concentrations of Ph, thus demonstrating the good biological relevance of cell-based electrochemical method. The strategy has been used to evaluate Ph antioxidant capacity in real cells with satisfactory results, indicating the feasibility of biosensor analysis for antioxidant evaluation.
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Affiliation(s)
- Yongli Ye
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Jian Ji
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Fuwei Pi
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Huicheng Yang
- Guangzhou GRE Metrology & Test Co., Ltd, Guangzhou, Guangdong 510000, PR China
| | - Jie Liu
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Yinzhi Zhang
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Shuang Xia
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Jiasheng Wang
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China
| | - Dan Xu
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, PR China
| | - Xiulan Sun
- State Key Laboratory of Food Science and Technology, School of Food Science, National Engineering Research Center for Functional Food, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
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