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Updated: Apr 24, 2026

Analytical Techniques for Assaying Nitric Oxide Bioactivity
Published on: June 18, 2012
Nitric oxide (NO) scavenging capacity of natural antioxidants
Yoshimi Sueishi1, Masashi Hori1, Masakazu Kita2
1Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
Abstract:
Nitric oxide (NO)-scavenging capacities of several hydrophilic antioxidants were determined by using the PTIO method, a competitive NO-scavenging method with 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). Relative NO-scavenging rates of antioxidants were measured with respect to PTIO and the scavenging rate constants were calculated based on PTIO's rate constant. Results indicated that NO-scavenging rate constants of the antioxidants were: uric acid (2.5)>caffeic acid (1.2)>trolox (1.0)>genistein (0.19)>glutathione (0) ≈N-acetylcysteine (0), where the numbers are expressed in trolox equivalent unit. The oxidation potentials of these antioxidants were measured and the order in the magnitude of oxidation potential was in good accordance with NO-scavenging capacity. Based on the results, we have suggested that the primary chemical process of the antioxidant reaction with NO can be characterised with the electron transfer from NO to the antioxidant.
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