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Haigh S, Brown ZL, Shivers MA, Sellers HG, West MA, Barman SA, Stepp DW, Csanyi G, Fulton DJR. A Reappraisal of the Utility of L-012 to Measure Superoxide from Biologically Relevant Sources. Antioxidants (Basel) 2023; 12:1689. [PMID: 37759992 PMCID: PMC10525458 DOI: 10.3390/antiox12091689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/29/2023] Open
Abstract
The detection of superoxide anion (O2●-) in biological tissues remains challenging. Barriers to convenient and reproducible measurements include expensive equipment, custom probes, and the need for high sensitivity and specificity. The luminol derivative, L-012, has been used to measure O2●- since 1993 with mixed results and concerns over specificity. The goal of this study was to better define the conditions for use and their specificity. We found that L-012 coupled with depolymerized orthovanadate, a relatively impermeable tyrosine phosphatase inhibitor, yielded a highly sensitive approach to detect extracellular O2●-. In O2●- producing HEK-NOX5 cells, orthovanadate increased L-012 luminescence 100-fold. The combination of L-012 and orthovanadate was highly sensitive, stable, scalable, completely reversed by superoxide dismutase, and selective for O2●- generating NOXes versus NOX4, which produces H2O2. Moreover, there was no signal from cells transfected with NOS3 (NO●) and NOS2(ONOO-). To exclude the effects of altered tyrosine phosphorylation, O2●- was detected using non-enzymatic synthesis with phenazine methosulfate and via novel coupling of L-012 with niobium oxalate, which was less active in inducing tyrosine phosphorylation. Overall, our data shows that L-012 coupled with orthovanadate or other periodic group 5 salts yields a reliable, sensitive, and specific approach to measuring extracellular O2●- in biological systems.
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Affiliation(s)
- Stephen Haigh
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - Zach L. Brown
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - Mitch A. Shivers
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - Hunter G. Sellers
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - Madison A. West
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - Scott A. Barman
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - David W. Stepp
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - Gabor Csanyi
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
| | - David J. R. Fulton
- Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
- David Fulton Vascular Biology Center, Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, CB 3316, Augusta, GA 30909, USA
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