Cited by 150Free Radicals and AntioxidantsBioactive Compounds and Antitumor AgentsRedox biology and oxidative stress

Apocynin: Chemical and Biophysical Properties of a NADPH Oxidase Inhibitor

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Petrônio, Maicon, Zeraik, Maria, Fonseca, Luiz, Ximenes, Valdecir·2013·Molecules

Abstract

Apocynin is the most employed inhibitor of NADPH oxidase (NOX), a multienzymatic complex capable of catalyzing the one-electron reduction of molecular oxygen to the superoxide anion. Despite controversies about its selectivity, apocynin has been used as one of the most promising drugs in experimental models of inflammatory and neurodegenerative diseases. Here, we aimed to study the chemical and biophysical properties of apocynin. The oxidation potential was determined by cyclic voltammetry (Epa = 0.76V), the hydrophobicity index was calculated (logP = 0.83) and the molar absorption coefficient was determined (e275nm = 1.1 × 104 M−1 cm−1). Apocynin was a weak free radical scavenger (as measured using the DPPH, peroxyl radical and nitric oxide assays) when compared to protocatechuic acid, used here as a reference antioxidant. On the other hand, apocynin was more effective than protocatechuic acid as scavenger of the non-radical species hypochlorous acid. Apocynin reacted promptly with the non-radical reactive species H2O2 only in the presence of peroxidase. This finding is relevant, since it represents a new pathway for depleting H2O2 in cellular experimental models, besides the direct inhibition of NADPH oxidase. This could be relevant for its application as an inhibitor of NOX4, since this isoform produces H2O2 and not superoxide anion. The binding parameters calculated by fluorescence quenching showed that apocynin binds to human serum albumin (HSA) with a binding affinity of 2.19 × 104 M−1. The association did not alter the secondary and tertiary structure of HSA, as verified by synchronous fluorescence and circular dichroism. The displacement of fluorescent probes suggested that apocynin binds to site I and site II of HSA. Considering the current biomedical applications of this phytochemical, the dissemination of these chemical and biophysical properties can be very helpful for scientists and physicians interested in the use of apocynin.

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Authors
Petrônio, M., Zeraik, M., Fonseca, L., & Ximenes, V.
Affiliations
Universidade Estadual Paulista (Unesp) (BR)
Corresponding author
Ximenes, Valdecir
Venue
Molecules
Publisher
MDPI AG
Published
2013-03-01
Volume
18
Issue
3
Pages
2821-2839
ISSN
1420-3049 (ISSN-L)
OpenAlex
W2036509107
Cited by
149
References
49
Citations by year
2026: 8 · 2025: 12 · 2024: 8 · 2023: 11 · 2022: 14 · 2021: 14 · 2020: 9 · 2019: 12 · 2018: 11 · 2017: 11 · 2016: 6 · 2015: 12 · 2014: 14 · 2013: 7
FWCI
5.91
Type
journal article
Language
en
Open access
Locations
  • Molecules (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Acervo Digital da Universidade Estadual Paulista (Universidade Estadual Paulista) (submittedVersion, other-oa)
  • Americanae (AECID Library) (submittedVersion, other-oa)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion, other-oa)
Funders
  • Fundação de Amparo à Pesquisa do Estado de São Paulo
  • Conselho Nacional de Desenvolvimento Científico e Tecnológico
Topics
  • Physical Sciences › Chemistry › Organic Chemistry › Free Radicals and Antioxidants
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Bioactive Compounds and Antitumor Agents
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
Keywords
apocynin, NADPH oxidase inhibitors, NOX4, superoxide, hydrogen peroxide scavenging, free radical scavenging, hypochlorous acid, protocatechuic acid, human serum albumin binding, fluorescence quenching, antioxidant activity, physicochemical properties
MeSH terms
Acetophenones, Enzyme Inhibitors, Hydrogen Peroxide, Hydrogen-Ion Concentration, Hypochlorous Acid, Kinetics, Oxidation-Reduction, Free Radical Scavengers, NADPH Oxidases, Hydrophobic and Hydrophilic Interactions

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