Antioxidant action of a lipophilic nitroxyl radical, cyclohexane‐1‐spiro‐2′‐(4′‐oxyimidazolidine‐1′‐oxyl)‐5′‐spiro‐1″‐cyclohexane, against lipid peroxidation under hypoxic conditions

Abstract

Nitroxyl radicals are known to act as radical scavenging antioxidants. In the present study, a lipophilic nitroxyl radical, cyclohexane-1-spiro-2'-(4'-oxyimidazolidine-1'-oxyl)-5'-spiro-1"-cyclohexane (nitroxyl radical I) was synthesized and its antioxidant capacity was assessed in comparison with a hydrophilic nitroxyl radical, 4-hydroxy-2,2,6,6-tetra-methylpiperidine-N-oxyl (Tempol). Both nitroxyl radical I and Tempol inhibited methyl linoleate oxidation induced by free radicals, and the efficacy increased with decreasing partial pressure of oxygen, the effect being more pronounced for nitroxyl radical I than Tempol. Their hydroxylamines inhibited lipid peroxidation more effectively than their corresponding parent nitroxyl radicals. In liposomal membranes, a synergistic effect was observed in the combination of nitroxyl radical I with ascorbic acid, whereas only an additive effect was observed between Tempol and ascorbic acid. The present study suggests that nitroxyl radical I and its hydroxylamine may act as potent antioxidants, especially in combination with ascorbic acid under hypoxic conditions.

4-Phenyl-1,2,4-triazaspiro[4.5]dec-1-ene-3-thione

“…For wide-spectrum medicinal applications of spiro compounds incorporating heterocyclic substructures, see: Patil et al (2010); Pawar et al (2009); Thadhaney et al (2010); Chin et al (2008); Wang et al (2007); Chande et al (2005); Obniska et al (2006); Kamiń ski et al (2008); Sarma et al (2010); Shimakawa et al (2003). For ring-puckering parameters, see: Cremer & Pople (1975).…”

Effects of Different Phases of Cigarette Smoke on Lipid Peroxidation and Membrane Structure in Liposomes

“…Examples par excellence are furnished by the smoke-borne NO and nitroxyl radicals. [16,30] Indeed, it is well known that both nitric oxide [31,32] and nitroxyl free radicals [33,34] are able to inhibit oxidation processes including lipid peroxidation. Clearly, this adds mechanistic intricacy to the development of the smoking-associated oxidative stress.…”

Synthesis and characterization of acetic acid functionalized poly (4-vinylpyridinium) salt as new catalyst for the synthesis of spiropyran derivatives and their biological activity

“…Many studies focus on new antioxidant agents without harmful side effects. Among new compounds, spiro compounds have also been recently used as antioxidants [65][66][67]. In the presented research, DPPH free radical scavenging activity of the new spiro-pyran derivatives was determined ( Table 5, 2 and Fig 9).…”

“…Studies focuses on antioxidant agents that can protect cell components from oxidative damage without harmful side effects [9]. Spiro compounds have also been recently used as antioxidants [10,11]. Today most of the microbes showed resistance to classical antibiotics [12,13] and the discovery of new compounds with novel mechanisms is a matter of urgency [14,15].…”