Proceedings of the 8th Brazilian Congress of Biotechnology

ELECTROCHEMICAL ASSESSMENT OF THIOL ANTIOXIDANT CAPACITY USING ABTS AS A REDOX MEDIATOR

Published in 21/11/2025 - ISBN: 978-65-272-1865-4

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Paper Title
ELECTROCHEMICAL ASSESSMENT OF THIOL ANTIOXIDANT CAPACITY USING ABTS AS A REDOX MEDIATOR
Authors
  • André Felippe de Almeida Xavier
  • Raul dos Santos Pereira
  • Leonardo Vieira da Silva
  • Marília Goulart
Modality
Abstract
Subject area
Technological Innovation;
Publishing Date
21/11/2025
Country of Publishing
Brazil | Brasil
Language of Publishing
en-US
Paper Page
https://www.even3.com.br/anais/biotecnologia2025/1257533-electrochemical-assessment-of-thiol-antioxidant-capacity-using-abts-as-a-redox-mediator
ISBN
978-65-272-1865-4
Keywords
ABTS, cyclic voltammetry, thiols, antioxidant capacity, electrochemical catalysis.
Summary
Background. ABTS•+ is widely used in spectrophotometric assays of antioxidant capacity. Here we explore a rapid electrochemical alternative to quantify the reactivity of biologically relevant thiols toward ABTS at neutral pH. Methods. Cyclic voltammetry (phosphate buffer, pH 7.0) was performed with ABTS fixed at 0.20 mM and each thiol—N-acetylcysteine (NAC), cysteine, homocysteine, and glutathione (GSH)—varied from 0.05 to 0.20 mM. Scan rates were 10–100 mV s⁻¹. From the voltammograms we obtained: (i) the cathodic peak current (I_pc1) versus √v, and (ii) the ratio I_pa/v versus v. Results. In the presence of all thiols, I_pc1 increased linearly with √v, indicating diffusion-controlled catalysis. The linear fits (I_pc1 vs √v) showed strong correlation for NAC (R² = 0.990), cysteine (R² = 0.998), and GSH (R² = 0.998); homocysteine also followed the trend with a single deviating point (R² = 0.847). Sensitivities (slopes of I_pc1 vs √v, in µA·V⁻¹ᐟ²·s¹ᐟ²) ranked GSH (18.3) > homocysteine (16.7) > cysteine (14.6) ≈ NAC (14.1), suggesting higher catalytic efficiency for GSH and homocysteine under our conditions. Complementarily, I_pa/v decreased consistently as v increased from 0.01 to 0.10 V s⁻¹—by ~78% (NAC), 70% (GSH), 67% (homocysteine), and 64% (cysteine)—a behavior characteristic of EC′-type mediation where chemical regeneration of the mediator limits current at lower scan rates. Together, these two diagnostics (I_pc1 ∝ √v and declining I_pa/v with v) support an ABTS-mediated catalytic mechanism for all tested thiols at pH 7.0. Conclusions. The data demonstrate the feasibility of a simple ABTS-mediated voltammetric protocol to rank thiol antioxidants and lay the groundwork for an electrochemical antioxidant capacity metric based on the slope of I_pc1 vs √v and/or catalytic current gains. Ongoing work extends the approach to phenolic antioxidants.
Title of the Event
8th Brazilian Biotechnology Congress.
City of the Event
Natal
Title of the Proceedings of the event
Proceedings of the 8th Brazilian Congress of Biotechnology
Name of the Publisher
Even3
Means of Dissemination
Meio Digital

How to cite

XAVIER, André Felippe de Almeida et al.. ELECTROCHEMICAL ASSESSMENT OF THIOL ANTIOXIDANT CAPACITY USING ABTS AS A REDOX MEDIATOR.. In: Proceedings of the 8th Brazilian Congress of Biotechnology. Anais...Natal(RN) Hotel Praia Mar, 2025. Available in: https//www.even3.com.br/anais/biotecnologia2025/1257533-ELECTROCHEMICAL-ASSESSMENT-OF-THIOL-ANTIOXIDANT-CAPACITY-USING-ABTS-AS-A-REDOX-MEDIATOR. Access in: 11/09/2026

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