title: DPPH and oxygen free radicals as pro-oxidant of biomolecules.
abstract: 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. Cu2+/ascorbate was used as generator system of oxygen free radical and as antioxidant, an extract of Buddleja globosa's leaves. Cu2+/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 Cu2+/ascorbate. Distinct redox mechanisms may explain the differences between the reactivity of DPPH and oxygen free radicals on biomolecules, which is discussed.
authors: Laboratory of Pharmacology, Department of Pharmacological and Toxicological Chemistry, Chemical and Pharmaceutical Sciences School, University of Chile, Olivos 1007, Independencia, Santiago, Chile. mel@ciq.uchile.cl
authors: María Eugenia
authors: ME
authors: Letelier
authors: Alfredo
authors: A
authors: Molina-Berríos
authors: Juan
authors: J
authors: Cortés-Troncoso
authors: José
authors: J
authors: Jara-Sandoval
authors: Marianne
authors: M
authors: Holst
authors: Karina
authors: K
authors: Palma
authors: Margarita
authors: M
authors: Montoya
authors: Dante
authors: D
authors: Miranda
authors: Víctor
authors: V
authors: González-Lira
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D001713:Biphenyl Compounds; D032861:Buddleja / Q000737:chemistry; D003300:Copper / Q000494:pharmacology; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D010636:Phenols / Q000032:analysis / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000494:pharmacology; D010851:Picrates / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D059808:Polyphenols; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D005419:Flavonoids; D007202:Indicators and Reagents; D016877:Oxidants; D010636:Phenols; D010713:Phosphatidylcholines; D010851:Picrates; D010936:Plant Extracts; D059808:Polyphenols; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D003300:Copper; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid