Antioxidant activity of anacardic acids

• Published in: Food chemistry Vol. 99; no. 3; pp. 555 - 562
• Main Authors: Kubo, Isao, Masuoka, Noriyoshi, Ha, Tae Joung, Tsujimoto, Kazuo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2006; Elsevier
• Subjects: anacardic acid; Anacardic acids; Anacardium occidentale; Antioxidant activity; bioactive properties; Biological and medical sciences; cashew fruit; cashew nuts; chelation; food analysis; Food industries; free radicals; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Inhibition kinetics; lipoxygenase; nuts; oxidation; physicochemical properties; reaction inhibition; reaction kinetics; reactive oxygen species; salicylates; salicylic acid; Soybean lipoxygenase-1; Xanthine oxidase; Xanthine oxidase; Anacardic acids; Inhibition kinetics; Antioxidant activity; Soybean lipoxygenase-1; Enzyme; Soybean; Antioxidant; Glycine max; Grain legume; Leguminosae; Dicotyledones; Angiospermae; Spermatophyta; Oxidoreductases; Kinetics; Inhibition; Lipoxygenase
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2005.08.023

Anacardic acids, 6-pentadec(en)ylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae) nut and apple, were found to possess preventive antioxidant activity while salicylic acid did not show this activity. These anacardic acids prevent generation of superoxide radicals by inhibiting xanthine oxidase (EC 1.1.3.22, Grade IV) without radical-scavenging activity. Notably, the inhibition kinetics of anacardic acids do not follow hyperbolic dependence of enzyme inhibition on inhibitor contents (Michaelis–Menten equation) but follow the Hill equation instead. Anacardic acid (C 15:1) inhibited the soybean lipoxygenase-1 (EC 1.13.11.12, Type 1) catalyzed oxidation of linoleic acid with an IC 50 of 6.8 μM. The inhibition is a slow and reversible reaction without residual enzyme activity. The inhibition kinetics indicate that anacardic acid (C 15:1) is a competitive inhibitor and the inhibition constant, K I, was 2.8 μM. Anacardic acids act as antioxidants in a variety ways, including inhibition of various prooxidant enzymes involved in the production of the reactive oxygen species and chelate divalent metal ions such as Fe 2+ or Cu 2+, but do not quench reactive oxygen species. The C 15-alkenyl side chain is largely associated with the activity.