DPPH and oxygen free radicals as pro-oxidant of biomolecules

• Published in: Toxicology in vitro 2008-03, Vol.22 (2), p.279-286
• Main Authors: Letelier, María Eugenia, Molina-Berríos, Alfredo, Cortés-Troncoso, Juan, Jara-Sandoval, José, Holst, Marianne, Palma, Karina, Montoya, Margarita, Miranda, Dante, González-Lira, Víctor
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants - pharmacology; Ascorbic Acid - pharmacology; Biomolecules herbal-protection; Biphenyl Compounds; Buddleja - chemistry; Buddleja globosa; Buddleja globosa-antioxidant properties; Copper - pharmacology; DPPH and oxygen free radicals; DPPH bleaching activity; Flavonoids - analysis; Flavonoids - pharmacology; In Vitro Techniques; Indicators and Reagents; Lipid Peroxidation - drug effects; Male; Microsomes, Liver - drug effects; Microsomes, Liver - metabolism; Oxidants - pharmacology; Oxidation-Reduction; Oxygen Consumption - drug effects; Phenols - analysis; Phenols - pharmacology; Phosphatidylcholines - pharmacology; Picrates - pharmacology; Plant Extracts - chemistry; Plant Extracts - pharmacology; Polyphenols; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species - pharmacology; Sulfhydryl Compounds - metabolism
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/j.tiv.2007.08.002

Numerous investigations exist about the alterations that oxygen free radicals can provoke on biomolecules; these modifications can be prevented and/or reversed by different antioxidants agents. On the other hand, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), a stable nitrogen synthetic radical, is used to evaluate the antioxidant capacity of medicinal herbal products; however, the structural changes that this radical provoke on the herbal active principles are not clear yet. In this work, we compared the redox reactivity of oxygen free radicals and DPPH radical on phospholipids and protein thiol groups present in rat liver microsomes. Cu 2+/ascorbate was used as generator system of oxygen free radical and as antioxidant, an extract of Buddleja globosa’s leaves. Cu 2+/ascorbate provoked microsomal lipid peroxidation, microsomal thiols oxidation and oxygen consumption; all of these phenomena were inhibited by B. globosa extract. On the other hand, DPPH was bleached in different extension by the herbal extract and phosphatidyl choline; beside, DPPH decreased microsomal thiols content, but this phenomenon were not prevented by the herbal extract. Furthermore, DPPH did not induce oxygen consumption and neither modified the oxygen consumption induced by Cu 2+/ascorbate. Distinct redox mechanisms may explain the differences between the reactivity of DPPH and oxygen free radicals on biomolecules, which is discussed.