Comparative pharmacology of chemically distinct NADPH oxidase inhibitors

Area of Science:

• Biochemistry
• Pharmacology
• Cardiovascular Research

Background:

• Oxidative stress, driven by reactive oxygen species (ROS), is implicated in various diseases.
• NADPH oxidases are potential sources of disease-relevant ROS.
• Concerns exist regarding the specificity of common NADPH oxidase inhibitors, necessitating re-evaluation of existing data.

Purpose of the Study:

• To compare the pharmacological profiles of established NADPH oxidase inhibitors (DPI, apocynin, AEBSF) with a novel inhibitor, VAS3947.
• To assess the specificity and efficacy of these inhibitors in various ROS detection assays.
• To identify reliable inhibitors for studying NADPH oxidase-derived ROS in disease models.

Main Methods:

• Pharmacological profiling of diphenylene iodonium (DPI), apocynin, 4-(2-amino-ethyl)-benzolsulphonyl-fluoride (AEBSF), and VAS3947.
• Utilized multiple assays for detecting cellular and tissue ROS, acknowledging limitations in specificity and artifact potential.
• Evaluated inhibitor effects on NADPH oxidase, nitric oxide synthase (NOS), xanthine oxidase (XOD), and endothelial NOS (eNOS) activities.

Main Results:

• DPI inhibited NADPH oxidase but also other flavo-enzymes (NOS, XOD).
• Apocynin and AEBSF showed variable efficacy and interfered with ROS detection.
• VAS3947 specifically inhibited NADPH oxidase in low micromolar concentrations without affecting ROS detection or other enzymes.
• VAS3947 reduced ROS formation in spontaneously hypertensive rat aortas where other inhibitors were ineffective.

Conclusions:

• Triazolo pyrimidines like VAS3947 are specific NADPH oxidase inhibitors.
• DPI and apocynin are not recommended due to lack of specificity.
• NADPH oxidases are identified as a major ROS source in the aortas of spontaneously hypertensive rats, based on VAS3947 effects.