Analysis of Kinetics of Dihydroethidium Fluorescence with Superoxide Using Xanthine Oxidase and Hypoxanthine Assay
Overview
Authors
Affiliations
Superoxide (O(2) (-)) is an important reactive oxygen species (ROS), and has an essential role in physiology and pathophysiology. An accurate detection of O(2) (-) is needed to better understand numerous vascular pathologies. In this study, we performed a mechanistic study by using the xanthine oxidase (XOD)/hypoxanthine (HX) assay for O(2) (-) generation and a O(2) (-) sensitive fluorescent dye dihydroethidium (DHE) for O(2) (-) measurement. To quantify O(2) (-) and DHE interactions, we measured fluorescence using a microplate reader. We conducted a detailed reaction kinetic analysis for DHE-O(2) (-) interaction to understand the effect of O(2) (-) self-dismutation and to quantify DHE-O(2) (-) reaction rate. Fluorescence of DHE and 2-hydroethidium (EOH), a product of DHE and O(2) (-) interaction, were dependent on reaction conditions. Kinetic analysis resulted in a reaction rate constant of 2.169 ± 0.059 × 10(3) M(-1) s(-1) for DHE-O(2) (-) reaction that is ~100× slower than the reported value of 2.6 ± 0.6 × 10(5) M(-1) s(-1). In addition, the O(2) (-) self-dismutation has significant effect on DHE-O(2) (-) interaction. A slower reaction rate of DHE with O(2) (-) is more reasonable for O(2) (-) measurements. In this manner, the DHE is not competing with superoxide dismutase and NO for O(2) (-). Results suggest that an accurate measurement of O(2) (-) production rate may be difficult due to competitive interference for many factors; however O(2) (-) concentration may be quantified.
Deena K, Maadurshni G, Manivannan J, Sivasamy R Mol Biol Rep. 2025; 52(1):144.
PMID: 39836269 DOI: 10.1007/s11033-025-10217-8.
A Co-Doping Materials Design Strategy for Selective Ozone Electrocatalysts.
Alaufey R, Keith J, Tang M J Phys Chem Lett. 2024; 15(28):7351-7356.
PMID: 38990156 PMC: 11261613. DOI: 10.1021/acs.jpclett.4c01150.
Alaufey R, Zhao L, Lindsay A, Siboonruang T, Wu Q, Keith J ACS Catal. 2024; 14(9):6868-6880.
PMID: 38933735 PMC: 11197020. DOI: 10.1021/acscatal.4c01317.
Kampaengsri S, Muangsopa P, Pangjantuk A, Chansaenpak K, Lai R, Noisa P ACS Appl Bio Mater. 2024; 7(6):3890-3899.
PMID: 38776245 PMC: 11190977. DOI: 10.1021/acsabm.4c00239.
Sytha S, Bray J, Heaps C Microvasc Res. 2023; 150:104590.
PMID: 37481160 PMC: 10538397. DOI: 10.1016/j.mvr.2023.104590.