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BY 4.0 license Open Access Published by De Gruyter Open Access March 1, 2023

A novel electrochemical micro-titration method for quantitative evaluation of the DPPH free radical scavenging capacity of caffeic acid

  • Xiaofen Li , Zhi Yang , Yuntao Gao EMAIL logo and Huabin Xiong EMAIL logo
From the journal Open Chemistry

Abstract

In this report, the stoichiometric ratio (R) for the interaction of diphenylpicrylhydrazyl (DPPH) radicals with the antioxidant was employed as an evaluation index for the DPPH radical scavenging activity of antioxidants. This evaluation index was related only to the stoichiometric relationship of DPPH radicals with the antioxidant and had no relationship with the initial DPPH amount and the sample volume, which could offer a solution to the problem of poor comparability of EC50 values under different conditions. A novel electrochemical micro-titration method was proposed for the determination of the stoichiometric ratio (R) for the interaction of DPPH radicals with the antioxidant. This electrochemical micro-titration model was verified using caffeic acid as the DPPH radical scavenger, with the stoichiometric ratio (R) of DPPH radicals to caffeic acid determined to be in the range of 2.003–2.046. The calculated EC50 values were 0.513, 1.011, and 1.981 × 10–5 mol/L for 2.10, 4.05, and 8.02 × 10–7 moL of added DPPH radicals, respectively. The proposed method showed no differences from the conventional method, but had better precision and reliability, and used a smaller amount of sample.

1 Introduction

In the last decade, many analytical methods have been developed to determine antioxidant activity in vitro, measure the ability to reduce oxidant species/probes, or scavenge free radicals, such as superoxide anion, hydroxyl, peroxyl, and alkoxyl radicals [1]. One such popular method for in vitro evaluation of antioxidant capacity is based on using stable free radical diphenylpicrylhydrazyl (DPPH) [2,3]. The DPPH method is described as a simple, rapid, accurate, and inexpensive assay that is widely used for the determination of radical scavenging activity [4,5,6,7]. Since the late 1950s, a variety of DPPH-based methods have been introduced for estimating the antioxidant activity of natural compounds or foods, including spectrophotometric [6], chemiluminescence [8], high-performance liquid chromatography with DPPH [911], gas chromatography mass spectrometry [12], fluorescence probe detection [13], and electron paramagnetic resonance methods [14]. Flow injection-based methods for the determination of scavenging capacity against DPPH have also been reported [15,16]. A DPPH-based optical sensor for screening antioxidant activity was introduced by Steinberg and Milardovic [17].

Electrochemical methods provide a rapid, simple, and sensitive alternative for analyzing bioactive compounds and determining antioxidant capacity and have still seen recent developments to determine the antioxidant activity [1820]. The relationship between the electrochemical behavior of compounds with antioxidant activity and their resulting “antioxidant power” (capacity) has attracted great interest due to “low oxidation potential” corresponding with “high antioxidant power” [21]. Cyclic voltammetry (CV) on carbon electrodes seems to be a suitable method for antioxidant capacity determination, especially due to its simplicity, rapidity, and ability to be used directly in biological and crude samples, including red and white wine, tea, coffee, juices, and even blood serum [22]. Differential pulse voltammetry (DPV), as a selective and sensitive technique, has also been explored in the detection of natural polyphenolic antioxidants in both complex and clinical samples [23]. Malagutti et al. used square wave voltammetry with a solid carbon polyurethane electrode (rigid carbon-polyurethane composite electrode) to compare the antioxidant capacity of green tea samples [24].

Electrochemical methods based on the amperometric reduction of DPPH have also been introduced, for example, the evaluation of DPPH free radical scavenging at a glassy carbon electrode or a platinum screen-printed working electrode [25,26]. Amatatongchai et al. [27] developed amperometric detection of the residual concentration of non-reacted DPPH using a carbon nanotube modified-glassy carbon electrode, which had sensitivity more than 25 times greater than that of the bare GC electrode. Milardović et al. used amperometric detection of DPPH free radical scavenging to evaluate the antioxidant activity of some water or ethanol-soluble pure compounds from samples of tea, wine, and some other beverages [28]. As mentioned earlier, electrochemical methods show good prospects in the determination of antioxidant capacity, but, to our knowledge, there have been few reports of voltammetric determination of DPPH scavenging activity. Recently, multi-walled carbon nanotubes (MWNTs) have been widely used in the fabrication of the modified electrode because of their huge specific surface area, strong mechanical performance, stable chemical property, good electrocatalytic effect, and charge transfer ability [2931].

Caffeic acid, known as 3,4-dihydroxycinnamic acid, is a typical phenolic acid compound found in plants. It is the main active ingredient in many traditional herbs, such as Terminalia and Penthorum chinense Pursh [32]. Pharmacological studies have proven that caffeic acid scavenges and inhibits free radical, antibiotic, antivirus, antitumor, decreasing blood lipid, hypoglycemic, and anti-aging activities, which has been widely applied in the medical industry [33].

A novel voltammetry-based electrochemical micro-titration method for the quantitative assessment of the DPPH free radical scavenging capacity of caffeic acid is described herein. This method is based on the stoichiometric relationship of the interaction between caffeic acid and DPPH free radicals, and a micro-titration method was proposed to determine this stoichiometric relationship. The stoichiometric ratio (R) of the stoichiometric relationship was employed as an evaluation index for DPPH radical scavenging activity. This method offers a rapid and inexpensive solution for the evaluation of DPPH radical scavenging activity in antioxidants.

2 Experimental

2.1 Reagents and chemicals

DPPH (1,1-diphenyl-2-picrylhydrazyl, purity > 99.0%) was obtained from Sigma-Aldrich (St. Louis, MO). Caffeic acid (trans-caffeic, purity > 99.0%) was purchased from the National Institute of China for the Control of Pharmaceutical and Biological Products (NICPBP, Beijing, China). All other reagents used were analytical-reagent grade. Twice-distilled water was used throughout all experiments.

The DPPH and caffeic acid were soluble in methanol. Fresh DPPH stock solution (10 mL) at a concentration of 0.1 mg/mL was prepared on each day of analysis. The stock solutions of caffeic acid were prepared in methanol at a concentration of 1.0 mg/mL. All stock solutions were stored at 4°C.

2.2 Apparatus

ZAHNER Zennium IM6 Electrochemical Workstation was the apparatus used (ZAHNER-elektrik GmbH & Co. KG, Kronach, Germany). A three-electrode system was established, using a GR-MWNTs/GCE working electrode, a platinum wire counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. Ultraviolet-visible (UV-Vis) spectrometry was recorded on an 8453 UV-Vis spectrophotometer (Agilent Technologies, USA).

The TNMH3 carboxyl functionalized multi-walled carbon nanotubes (MWNTs, purity > 95%), purchased from Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences; spectrum pure graphite rod (purchased from Qingdao tengrui carbon co., LTD, diameter: 0.6 cm).

2.3 Experimental methods

2.3.1 Preparation for the modified electrode

First, 6 cm graphite rod was taken and sealed in the polyethylene pipe using an epoxy resin binder. One of the ends was used as an electrode connection, and the other end was polished to a mirror-like surface with the different sizes of the metallographic sandpaper. Then, the mirror side was carefully polished for about 15 min using functionalized MWNTs on parchment paper, in order to embed MWNTs uniformly on the surface of the electrode and got the inlaid MWNTs/GE. Finally, the prepared electrode was electrochemically cleaned in a based solution by cycling potentials between −0.4 and +2.0 V at 0.1 V/s until a steady cyclic voltammogram was obtained.

2.3.2 Electrochemical behavior of the interaction of CA and DPPH free radicals

A certain amount of 1 mg/mL CA solution was taken into a 10 mL colorimetric tube, which was diluted to a fixed volume with a concentration of 0.1 mg/mL HAc-NaAc buffer solution. CA solution was transferred to an electrolytic tank and connected to the three-electrode cell in pH 4.0 HAc-NaAc buffer solution between the potential range of 0.1 and 0.8 V at a scan rate of 50 mV/s. Recorded the CV curve of CA. At the same time, DPV curves of CA were measured under the conditions: pulse width 200 ms, pulse amplitude 20 mV, and pulse interval 250 ms.

2.3.3 Electrochemical micro-titration of CA scavenging DPPH radical

About 1.0 mL of CA solution at a certain concentration was added to 9.0 mL of 0.1 mg/mL HAc-NaAc buffer solution (pH 4.0). CV and DPV analysis of the mixed solutions was performed using the three-electrode system in the potential range 0.1–0.8 V (vs SCE). Then, a certain volume of 1.0 × 10–3 moL/L DPPH solution was added into the mixed solution successively using a 10.0-μL microsyringe with stirring until the value of the DPV oxidation peak was almost unchanged. The changes in oxidation peak in CV and DPV during this process were measured.

3 Results and discussion

3.1 Electrochemical behavior of the interaction of caffeic acid with DPPH

Figure 1 shows the cyclic voltammograms (CV) of the interaction of caffeic acid with DPPH free radicals in HAc-NaAc buffer solution (pH = 4.0) at the graphite electrode. A pair of quasi-reversible redox peaks with peak potentials of E pa = 0.42 V (vs SCE) and E pc = 0.27 V can be observed, while the redox peaks of DPPH were not observed under the same conditions. This result suggested that the caffeic acid electrochemical reaction displayed a typical quasi-reversible process. There was a good linear relationship between oxidation or reduction peak current and scan rate (v), with a linear regression equation of i pa (μA) = 255.7ν + 27.49 (r = 0.9979) or i pa (μA) = 246.3ν + 27.04 (r = 0.9980), respectively, which showed that the reaction process was mainly controlled by adsorption. Figure 1c–d shows that both the oxidation peak and reduction peak of caffeic acid significantly decreased with the addition of DPPH, from 2.0 × 10–5 to 4.0 × 10–5 mol/L, while their peak potential remained almost unchanged, indicating that caffeic acid was consumed and reduced according to a dose–effect relationship when DPPH was added.

Figure 1 
                  The cyclic voltammograms of the interaction of caffeic acid with DPPH: (a) graphite electrode; (b) 5.0 × 10−5 moL/L caffeic acid; (c) b + 2.0 × 10−5 moL/L DPPH; (d) b + 4.0 × 10−5 moL/L DPPH.
Figure 1

The cyclic voltammograms of the interaction of caffeic acid with DPPH: (a) graphite electrode; (b) 5.0 × 10−5 moL/L caffeic acid; (c) b + 2.0 × 10−5 moL/L DPPH; (d) b + 4.0 × 10−5 moL/L DPPH.

The DPV curves of the interaction of caffeic acid with DPPH are shown in Figure 2. A sensitive DPV oxidation peak was observed for caffeic acid at 0.35 V (vs SCE). The oxidation peak current of caffeic acid decreased remarkably with the addition of DPPH, as depicted by curves b–e in Figure 2. A good linear relationship was observed between the oxidation peak current (i pa) and the caffeic acid concentration (c), with a linear regression equation of i pa (mA) = 53.444c (μmol/L) + 2.7513 (r = 0.9991), meaning that the interaction of caffeic acid with DPPH could be more clearly evaluated via DPV by adding DPPH gradually into caffeic acid solution. Furthermore, a good linear relationship between the oxidation peak current of caffeic acid decreasing (Δi pa) and the cumulative amount of added DPPH (n DPPH) was obtained when varying its concentration from 1.0 × 10–5 to 6.0 × 10–5 moL/L, and the linear regression equation could be described as follows: Δi pa (μA) = 10.708n DPPH – 0.242 (r = 0.9980). These results suggested that caffeic acid and DPPH interacted according to a certain stoichiometric relationship.

Figure 2 
                  The differential pulse voltammeter curves of the interaction of caffeic acid with DPPH: (a) 5.0 × 10−5 moL/L caffeic acid; (b) a + 1.0 × 10−5 moL/L DPPH; (c) a + 2.0 × 10−5 moL/L DPPH; (d) a + 4.0 × 10−5 mol/L DPPH; (e) a + 6.0 × 10−5 moL/LDPPH.
Figure 2

The differential pulse voltammeter curves of the interaction of caffeic acid with DPPH: (a) 5.0 × 10−5 moL/L caffeic acid; (b) a + 1.0 × 10−5 moL/L DPPH; (c) a + 2.0 × 10−5 moL/L DPPH; (d) a + 4.0 × 10−5 mol/L DPPH; (e) a + 6.0 × 10−5 moL/LDPPH.

3.2 Mathematical model of electrochemical micro-titration

The concentration of caffeic acid showed a good linear relationship with the oxidation peak current (i pa), as mentioned earlier, which can be depicted as follows:

(1) i pa = K c CA + b ,

where c CA and i pa represent the concentration and oxidation peak current of caffeic acid, respectively. c CA decreases with the addition of DPPH, resulting in a decrease in i pa, as described by equation (2):

(2) Δ i pa = i pa 0 i pa = K ( c CA 0 c CA ) = K n CA 0 V 0 n CA V 0 + i = 1 N V i ,

where i pa 0 , c CA 0 , and n CA 0 represent the initial oxidation peak current, concentration, and amount of caffeic acid, respectively; V 0 is the initial volume of the solution mixture for analysis; n CA is the amount of caffeic acid; V i is the volume for a single addition of DPPH; and i = 1 N V i is the volume change during the titration process. In our experiment, V 0 and V i were 10.0 mL and 10.0 μL, respectively, and the number of additions was about 10; thus, the volume change in the titration process was less than 1.0%. equation (2) can be reformulated as follows:

(3) Δ i pa = K V 0 ( n CA 0 n CA ) = K V 0 Δ n CA ,

where Δn CA is the amount of caffeic acid consumed by DPPH in the titration process. According to the aforementioned experimental result, the interaction between caffeic acid and DPPH was based on a certain stoichiometric relationship, meaning that DPPH might react with caffeic acid according to a stoichiometric ratio of R, R = 1.983, Δn CA = Rn DPPH. Therefore, equation (3) can be further rewritten as:

(4) Δ i pa = K V 0 Δ n CA = K R V 0 n DPPH ,

where R is the stoichiometric ratio, nDPPH is the amount of DPPH consumed in the titration process, K is the slope of the linear regression equation (equation (2)) for the oxidation peak current (i pa), and the caffeic acid concentration (c) can be calculated using equation (1). As shown in equation (2), Δn CA (in equation (2)) could be transformed when nDPPH was added, which meant that the stoichiometric ratio (R) for DPPH and caffeic acid could be easily obtained using the proposed electrochemical micro-titration method. The evaluation of DPPH radical scavenging activity of antioxidants is normally based on the median elimination concentration (EC50), as defined in equation (5):

(5) EC 50 ( mol / L ) = c A50 = n A50 V 0 ,

where c A50 and n A50 are the median elimination concentration and amount of antioxidants that cause the initial DPPH concentration to decrease by 50%, respectively. Substituting the stoichiometric ratio of R = n DPPHn CA into equation (5) gives the following equation:

(6) EC 50 ( mol / L ) = n A50 V 0 = n DPPH 0 2 R V 0 ,

where n DPPH 0 is the initial amount of DPPH. equation (6) shows an alternative way to calculate EC50 using the stoichiometric ratio of DPPH and antioxidant. Moreover, the stoichiometric ratio (R) could also be used as a key parameter to characterize the antioxidant capacity of antioxidant compounds. For a certain antioxidant compound, a higher R value denotes the ability to scavenge more DPPH radicals and possession of a higher antioxidant capacity.

3.3 Electrochemical micro-titration of caffeic acid scavenging DPPH radicals

Electrochemical micro-titration was performed according to the method in Section 2. Figure 3 shows the titration curve, which depicts the cumulative added amounts of DPPH (n DPPH) and the change in oxidation peak current value of caffeic acid (Δi pa), calculated using equation (2). Δi pa increased rapidly with the addition of DPPH and remained almost unchanged after DPPH addition reached a certain amount, indicating that caffeic acid was consumed almost completely. The inflexion in the titration curve can be characterized as the endpoint.

Figure 3 
                  The titration curve of the cumulative addition amounts of DPPH and the value of oxidation peak current change of caffeic acid (Δi
                     pa). n
                     DPPH = 2.10 × 10−7 moL, n
                     CA = 1.00 × 10−7 moL (curve 1); n
                     DPPH = 4.05 × 10−7 moL, n
                     CA = 2.00 × 10−7 moL (curve 2); n
                     DPPH = 8.02 × 10−7 moL, n
                     CA = 4.00 × 10−7 moL (curve 3); V
                     0 = 10.0 mL, 10.0 μL of 1.0 × 10−4 mol/L DPPH for each addition.
Figure 3

The titration curve of the cumulative addition amounts of DPPH and the value of oxidation peak current change of caffeic acid (Δi pa). n DPPH = 2.10 × 10−7 moL, n CA = 1.00 × 10−7 moL (curve 1); n DPPH = 4.05 × 10−7 moL, n CA = 2.00 × 10−7 moL (curve 2); n DPPH = 8.02 × 10−7 moL, n CA = 4.00 × 10−7 moL (curve 3); V 0 = 10.0 mL, 10.0 μL of 1.0 × 10−4 mol/L DPPH for each addition.

The stoichiometric ratio (R) of the reaction of caffeic acid with DPPH radicals was calculated using equation (4) based on the titration curve in Figure 3. And the result of stoichiometric ratio (R) is shown in Table 1. Moreover, the EC50 of CA was calculated using the stoichiometric ratio (R) according to equation (6). The EC50 result was compared with conventional photometric analysis, as shown in Table 2. The R value was consistent for different n DPPH values, and the EC50 increased with the increase in n DPPH. The EC50 resulting from this method was in agreement with that of the conventional method, and had a lower RSD, indicating that this method was reliable.

Table 1

Results of stoichiometric ratio (R) (n = 6)

Initial caffeic acid amount/(n 0 × 10−7 moL) DPPH added for consumed almost completely/(n 0 × 10−7 moL) Stoichiometric ratio/( R ¯ ± RSD/%) Δi pa (μA) = Kn DPPH + b V 0/mL
1.00 2.10 2.046 ± 3.14 Δi pa (μA) = 10.935n DPPH − 0.060 (r = 0.998) 10
2.00 4.05 2.003 ± 2.07 Δi pa (μA) = 10.708n DPPH − 0.242 (r = 0.998) 10
4.00 8.02 2.024 ± 2.69 Δi pa (μA) = 10.818n DPPH − 0.461 (r = 0.998) 10
Table 2

Results of half of the scavenging rate (EC50) (n = 6)

DPPH amount/(n 0 × 10−7 moL) Stoichiometric ratio/( R ¯ ± RSD/%) EC ¯ 50% × 10−5mol/L ± RSD/%
2.10 1.956 ± 2.12 0.518 + 3.82
4.05 2.015 ± 2.85 1.015 + 3.62
8.02 1.945 ± 2.75 1.989 + 2.82

3.4 The spectroscopy study of CA scavenging DPPH radical

The DPPH radical scavenging activity of CA was also determined by conventional photometric analysis [34], the result is shown in Figure 4, a good linear relationship between CA concentration and scavenging rate was obtained, with a linear regression equation of E (%) = 14,518c + 0.1980 (r = 0.9910) before reaching the maximum, which ensure experimental results possesses better accuracy. The EC50 was calculated based on the linear regression equation, as shown in Table 2.

Figure 4 
                  DPPH radical scavenging activity of CA.
Figure 4

DPPH radical scavenging activity of CA.

Traditional evaluation methods for estimating the DPPH radical scavenging activity of antioxidants are mainly based on the median elimination concentration (EC50). However, the inadequacies of this method are that EC50 values for the same antioxidants under different conditions are quite different due to clear changes in EC50 with changing initial DPPH amounts and sample volumes used for determination. Therefore, an electrochemical micro-titration method was used to obtain the stoichiometric ratio (R) of CA for DPPH radical scavenging. And the stoichiometric ratio (R) for the interaction of DPPH radicals with the antioxidant was employed as an evaluation index for the DPPH radical scavenging activity of antioxidants. And the result indicated that this evaluation index was related only to the stoichiometric relationship of DPPH radicals with the antioxidant and had no relationship with the initial DPPH amount and the sample volume, which could overcome the problem of poor comparability of EC50 values under different conditions. Furthermore, the EC50% values corresponding to different initial DPPH can be accurately deduced according to the R value, and the results are consistent with the conventional method. Therefore, the stoichiometric ratio (R) is superior to the conventional methods in terms of comparability, applicability, and reliability in evaluating antioxidant activity, and the amount of reagent is significantly reduced, which reduces the analysis cost and it has a good application prospect.

4 Conclusion

In this report, a novel sensitive electrochemical micro-titration method for determination and estimation of the DPPH free radical scavenging activity of active materials was proposed based on the interaction between caffeic acid and DPPH. An electrochemical micro-titration model was established based on titration curves between oxidation peak current change of the antioxidant (Δi pa) and the added amount of DPPH radicals in the titration process. The stoichiometric ratio (R) for the reaction of antioxidant with the amount of DPPH radicals added was determined using the obtained titration equation, while the DPPH median elimination concentration (EC50) of antioxidants was calculated from the stoichiometric ratio (R). The above-mentioned electrochemical micro-titration model, verified using caffeic acid, indicated that the proposed method was simple, quick, sensitive, and low cost, providing a novel approach to the evaluation of antioxidant properties.

  1. Funding information: This work was supported by the National Natural Science Fundation of China (No. 201367025), and program for the National Natural Science Fundation of China (No. 21665027), and program for the Applied Basic Research Project of Yunnan Province Youth Program (No. 2017FD118), and Scientific research fund project of Yunnan Education Department (No. 2022J0443).

  2. Author contributions: Investigation: X.L., X.H.; resources: Y.G., X.H.; funding acquisition: Y.G., X.H.; methodology: Z.Y.; data curation: X.L.

  3. Conflict of interest: We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, and there is no professional or other personal interest of any nature or kind in any product, service, and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “A Novel Electrochemical Micro-Titration Method for Quantitative Evaluation of the DPPH Free Radical Scavenging Capacity of Caffeic Acid.”

  4. Ethical approval: The conducted research is not related to either human or animal use.

  5. Data availability statement: Raw data were generated at facility name: ZAHNER Zennium IM6 Electrochemical Workstation, UV–Vis spectrophotometer, etc. Derived data supporting the findings of this study are available from the corresponding author on request. The data sets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

References

[1] Apak R, Gorinstein S, Böhm V, Schaich KM, Özyürek M, Güçlü K. Methods of measurement and evaluation of natural antioxidant capacity/activity (IUPAC Technical Report). Pure Appl Chem. 2013;85:957–98.10.1351/PAC-REP-12-07-15Search in Google Scholar

[2] Oliveira G, Tormin TF, Sousa R, Oliveira AD, Morais SD, Richter EM, et al. Batch-injection nalysis with amperometric detection of the DPPH radical for evaluation of antioxidant capacity. Food Chem. 2016;192:691–7.10.1016/j.foodchem.2015.07.064Search in Google Scholar PubMed

[3] Zhang Y, Shen Y, Zhu Y. Assessment of the correlations between reducing power, scavenging DPPH activity and anti-lipid-oxidation capability of phenolic antioxidants. LWT. 2015;63:569–74.10.1016/j.lwt.2015.03.047Search in Google Scholar

[4] Pedan V, Fischer N, Rohn S. An online NP-HPLC-DPPH method for the determination of the antioxidant activity of condensed polyphenols in cocoa. Food Res Int. 2016;89:890–900.10.1016/j.foodres.2015.10.030Search in Google Scholar

[5] Vít Mareek Mikyka A, Hampel D, Ejka P, Cerkal R. ABTS and DPPH methods as a tool for studying antioxidant capacity of spring barley and malt. J Cereal Sci. 2017;73:40–5.10.1016/j.jcs.2016.11.004Search in Google Scholar

[6] Ricci A, Parpinello GP, Tesli N, Kilmartin PA, Versari A,. Suitability of the cyclic voltammetry measurements and DPPH spectrophotometric assay to determine the antioxidant capacity of food-grade oenological tannins. Molecules. 2019;24:2925–30.10.3390/molecules24162925Search in Google Scholar PubMed PubMed Central

[7] Sridhar K, Charles AL. In vitro antioxidant activity of Kyoho grape extracts in DPPH and ABTS assays: Estimation methods for EC50 using advanced statistical programs. Food Chem. 2019;275:41–9.10.1016/j.foodchem.2018.09.040Search in Google Scholar PubMed

[8] Benchennouf A, Grigorakis S, Loupassaki S, Kokkalou E. Phytochemical analysis and antioxidant activity of Lycium barbarum (Goji) cultivated in Greece. Pharm Biol. 2017;55:596–602.10.1080/13880209.2016.1265987Search in Google Scholar PubMed PubMed Central

[9] Geng DD, Chi XF, Dong Q. Antioxidants screening in Limonium aureum by optimized on-line HPLC-DPPH assay. Ind Crop Prod. 2015;67:492–7.10.1016/j.indcrop.2015.01.063Search in Google Scholar

[10] Lei F, Hua Z, Jie Z, Geng Y, Wang X. Rapid screening and preparative isolation of antioxidants from Alpinia officinarum hance using HSCCC coupled with DPPH-HPLC assay and evaluation of their antioxidant activities. J Anal Methods Chem. 2018;31:293–9.Search in Google Scholar

[11] Im DY, Pyo BS, Kim SM, Lee KI. Measurement of the Anti-oxidative properties of extract from medicinal plants using an on-line HPLC-DPPH assay. J Life Sci. 2017;27:44–9.10.5352/JLS.2017.27.1.44Search in Google Scholar

[12] Carrasco A, Ortiz-Ruiz V, Martinez-Gutierrez R, Tomas V, Tudela J. Lavandula stoechas essential oil from Spain: Aromatic profile determined by gas chromatography-mass spectrometry, antioxidant and lipoxygenase inhibitory bioactivities. Ind Crop Prod. 2015;73:16–27.10.1016/j.indcrop.2015.03.088Search in Google Scholar

[13] Becerra-Herrera M, Beltrán R. Exploring antioxidant reactivity and molecular structure of phenols by means of two coupled assays using fluorescence probe (2,3-diazabicyclo[2.2.2]oct-2-ene, DBO) and free radical (2, 2-diphenyl-1-picrylhydrazyl, DPPH). J Chem Sci. 2017;129:1381–90.10.1007/s12039-017-1331-1Search in Google Scholar

[14] Chaudhuri U, Mahendiran R. Magnetoimpedance based detection of L-band electron paramagnetic resonance in 2,2-diphenyl-1-picrylhydrazyl (DPPH) molecule. arXiv Prepr arXiv. 2020;8:1–16.Search in Google Scholar

[15] Ricci A, Teslic N, Petropolus VI, Parpinello GP, Versari A. Fast analysis of total polyphenol content and antioxidant activity in wines and oenological tannins using a flow injection system with tandem diode array and electrochemical detections. Food Anal Methods. 2019;12:347–54.10.1007/s12161-018-1366-zSearch in Google Scholar

[16] Nalewajko-Sieliwoniuk E, Malejko J, Pawlukiewicz A, Kojo A. A Novel Multicommuted flow method with nanocolloidal manganese (IV)-based chemiluminescence detection for the determination of the total polyphenol index. Food Anal Methods. 2016;9:991–1001.10.1007/s12161-015-0274-8Search in Google Scholar

[17] Ivana MS, Stjepan M. Chromogenic radical based optical sensor membrane for screening of antioxidant activity. Talanta. 2007;71:1782–7.10.1016/j.talanta.2006.08.015Search in Google Scholar PubMed

[18] Chochevska M, Seniceva EJ, Velikovska SK, Naumova-Leia G, Esatbeyoglu T. Electrochemical determination of antioxidant capacity of traditional homemade fruit vinegars produced with double spontaneousfermentation. Microorganisms. 2021;9:1946–56.10.3390/microorganisms9091946Search in Google Scholar PubMed PubMed Central

[19] Karimi-Maleh H, Orooji Y, Karimi F, Alizadeh M, Baghayeri M, Rouhi J, et al. A critical review on the use of potentiometricbased biosensors for biomarkers detection. Biosens Bioelectron. 2021;184:113252.10.1016/j.bios.2021.113252Search in Google Scholar PubMed

[20] Karaman C, Karaman O, Atar N, Yola ML,. Sustainable electrode material for high-energy supercapacitor: biomass-derived graphene-like porous carbon with three dimensional hierarchically ordered ion highways. Phys Chem Chem Phys. 2021;23:12807–21.10.1039/D1CP01726HSearch in Google Scholar PubMed

[21] Firuzi O, Lacanna A, Petrucci R, Marrosu G, Saso L. Evaluation of the antioxidant activity of flavonoids by “ferric reducing antioxidant power” assay and cyclic voltammetry. Biochimica et Biophysica Acta (Biochim Biophys Acta), BBA-GEN SUBJECTS. 2005;1721:174–84.10.1016/j.bbagen.2004.11.001Search in Google Scholar PubMed

[22] Castro S, Silva CV, Stefano JS, Richter EM, Munoz R. Voltammetric determination of traces of 4-chloroaniline in antiseptic samples on a cathodically-treated boron-doped diamond electrode. J Electroanal Chem. 2020;877:114500.10.1016/j.jelechem.2020.114500Search in Google Scholar

[23] Šeruga M, Novak I, Jakobek L. Determination of polyphenols content and antioxidant activity of some red wines by differential pulse voltammetry, HPLC and spectrophotometric methods. Food Chem. 2011;124:1208–16.10.1016/j.foodchem.2010.07.047Search in Google Scholar

[24] Malagutti AR, Zuin VG, Cavalheiro ÉT, Mazo LH. Determination of rutin in green tea infusions using square-wave voltammetry with a rigid carbon-polyurethane composite electrode. Electroanalysis. 2006;18:1028–34.10.1002/elan.200603496Search in Google Scholar

[25] Luna PJJ, Mendoza S, Cardenas AI. Comparison of electrochemical methods using CUPRAC, DPPH and carbon paste electrodes for the quantification of antioxidants in food oils. Anal Methods. 2019;11:1–7.Search in Google Scholar

[26] Romero MR, Estévez R, Rodríguez Mellado JM, González-Rodríguez J, Montoya MR, Rodríguez-Amaro R. Exploring the relation between composition of extracts of healthy foods and their antioxidant capacities determined by electrochemical and spectrophotometrical methods. LWT. 2018;95:157–66.10.1016/j.lwt.2018.04.079Search in Google Scholar

[27] Amatatongchai M, Laosing S, Chailapakul O, Nacapricha D. Simple flow injection for screening of total antioxidant capacity by amperometric detection of DPPH radical on carbon nanotube modified-glassy carbon electrode. Talanta. 2012;97:267–72.10.1016/j.talanta.2012.04.029Search in Google Scholar PubMed

[28] Milardović S, Iveković D, Božidar S. A novel amperometric method for antioxidant activity determination using DPPH free radical. Bioelectrochemistry. 2006;68:175–80.10.1016/j.bioelechem.2005.06.005Search in Google Scholar PubMed

[29] Zhao Y, Yuan YC, Bai XL, Liu YM, Wu GF, Yang FS. Multi-mycotoxins analysis in liquid milk by uhplc-q-exactive hrms after magnetic solid-phase extraction based on pegylated multi-walled carbon nanotubes. Food Chem. 2020;305:1–8.10.1016/j.foodchem.2019.125429Search in Google Scholar PubMed

[30] Zou J, Yuan MM, Huang ZN, Chen XQ, Jiang XY, Jiao FP. Highly-sensitive and selective determination of bisphenol in milk samples based on self-assembled graphene nanoplatelets-multiwalled carbon nanotube-chitosan nanostructure. Mat Sci Eng. 2019;103:1–11.10.1016/j.msec.2019.109848Search in Google Scholar PubMed

[31] Kong D, Jiang L, Liu Y, Wang Z, Han L, Lv R. Electrochemical investigation and determination of procaterol hydrochloride on poly (glutamic acid)/carboxyl functionalized multiwalled carbon nanotubes/polyvinyl alcohol modified glassy carbon electrode. Talanta. 2017;174:436–43.10.1016/j.talanta.2017.06.047Search in Google Scholar PubMed

[32] Shiozawa R, Inoue Y, Murata I, Kanamoto I. Effect of antioxidant activity of caffeic acid with cyclodextrins using ground mixture method. Asian J Pharm. 2018;13:26–35.10.1016/j.ajps.2017.08.006Search in Google Scholar PubMed PubMed Central

[33] Symes A, Shavandi A, Zhang H, Mohamed Ahmed IA, Al-Juhaimi FY, Bekhit AE. Antioxidant activities and Caffeic acid content in New Zealand Asparagus (Asparagus officinalis) roots extracts. Antioxidants. 2018;7:52–60.10.3390/antiox7040052Search in Google Scholar PubMed PubMed Central

[34] Lu YW, Li XF, Gao YT. UV-Vis absorption spectrometric investigation of the gallic acid against DPPH free radicals. Sci Tech Food Chem. 2014;2:124–30.Search in Google Scholar

Received: 2022-06-30
Revised: 2022-10-03
Accepted: 2022-10-15
Published Online: 2023-03-01

© 2023 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

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