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The calcium channel modulator 2-APB hydrolyzes in physiological buffers and acts as an effective radical scavenger and inhibitor of the NADPH oxidase 2
2-aminoethoxydiphenyl borate (2-APB) is commonly used as a tool to modulate calcium signaling in physiological studies. 2-APB has a complex pharmacology and acts as activator or inhibitor of a variety of Ca(2+) channels and transporters. While unspecific, 2-APB is one of the most-used agents to modu...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Elsevier
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10009725/ https://www.ncbi.nlm.nih.gov/pubmed/36889081 http://dx.doi.org/10.1016/j.redox.2023.102654 |
Sumario: | 2-aminoethoxydiphenyl borate (2-APB) is commonly used as a tool to modulate calcium signaling in physiological studies. 2-APB has a complex pharmacology and acts as activator or inhibitor of a variety of Ca(2+) channels and transporters. While unspecific, 2-APB is one of the most-used agents to modulate store-operated calcium entry (SOCE) mediated by the STIM-gated Orai channels. Due to its boron core structure, 2-APB tends to readily hydrolyze in aqueous environment, a property that results in a complex physicochemical behavior. Here, we quantified the degree of hydrolysis in physiological conditions and identified the hydrolysis products diphenylborinic acid and 2-aminoethanol by NMR. Notably, we detected a high sensitivity of 2-APB/diphenylborinic acid towards decomposition by hydrogen peroxide to compounds such as phenylboronic acid, phenol, and boric acid, which were, in contrast to 2-APB itself and diphenylborinic acid, insufficient to affect SOCE in physiological experiments. Consequently, the efficacy of 2-APB as a Ca(2+) signal modulator strongly depends on the reactive oxygen species (ROS) production within the experimental system. The antioxidant behavior of 2-APB towards ROS and its resulting decomposition are inversely correlated to its potency to modulate Ca(2+) signaling as shown by electron spin resonance spectroscopy (ESR) and Ca(2+) imaging. Finally, we observed a strong inhibitory effect of 2-APB, i.e., its hydrolysis product diphenylborinic acid, on NADPH oxidase (NOX2) activity in human monocytes. These new 2-APB properties are highly relevant for Ca(2+) and redox signaling studies and for pharmacological application of 2-APB and related boron compounds. |
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