Catalase is more sensible to the inhibitory effect of soluble component of tobacco smoke than Glutathione Peroxidase and Superoxide Dismutase

espanolEl humo de tabaco causa dano oxidativo directamente por efecto de sus oxidantes o indirectamente por la induccion de la produccion de oxidantes endogenos y/o inactivacion de antioxidantes. El efecto oxidativo del humo de tabaco depende de varias variables: dosis, tiempo de exposicion, tejido o tipo cleular y estado antioxidante. En un intento de simplificar este complejo escenario, examinamos el efecto de un extracto soluble de humo de tabaco en la actividad de tres enzimas antioxidantes en estado purificado y en plasma humano (catalasa, glutation peroxidasa and superoxido dismutasa). Nuestro resultados revelan que catalasa y glutation peroxidasa fueron inhibidas con un IC50 de 18 y 80 equivalentes de fumador (unidades arbirtarias), respectivamente; mientras que superoxido dismutasa no fue afectada. Encontramos un efecto similar del extracto soluble de humo de tabaco en las enzimas antioxidantes plasmaticas, donde catalasa fue mas inhibida que superoxido dismutasa y glutation peroxidasa aumento 20% su actividad. Benzo[a]pireno, un conocido componente del humo de tabaco, fue parcialmente responsable del la inhibicicon de catalasa. Aunque el extracto soluble del humo de tabaco y el benzo[a]pireno indujeron carbonilacion de las proteinas plasmaticas, descartamos que esta modificacion sera responsable de la inhibicion de catalasa, porque la dialisis revertio su efecto. Considerando la alta sensibilidad de catalasa a la inhibicion por extracto de humo de tabaco y benzo[a]pireno en particular, concluimos que el extracto de humo de tabaco promueve una acumulacion transiente de peroxidos que podria ser uno de los factores responsables del dano oxidativo observado en el tracto respiratorio y en otros tejidos de sujetos fumadores. EnglishTobacco smoke causes oxidative damage directly by the effect of their oxidants or indirectly through the induction of endogenously produced oxidants and/or inactivation of antioxidants. The oxidative effect of tobacco smoke depends on many variables: dose, time of exposure, tissue or cell type and endogenous antioxidant status. In an attempt to simplify this complex scenario, we examined the effect of a soluble extract of tobacco smoke on the activity of purified antioxidant enzymes (catalase, glutathione peroxidase and superoxide dismutase) and in human plasma. Our results revealed that catalase and glutathione peroxidase were inhibited with an IC50 of 18 and 80 smoker equivalents (arbitrary units), respectively; meanwhile superoxide dismutase was not affected. A similar effect of soluble extract of tobacco smoke was obtained for antioxidant enzymes in human plasma, where catalase was inhibited, while superoxide dismutase was little affected, and glutathione peroxidase increased 20% its activity. Benzo[a]pyrene, a well-known component of tobacco smoke, was partly responsible for catalase inactivation. Although soluble extract of tobacco smoke and benzo[a]pyrene both induced carbonylation of plasma proteins, we ruled out that catalase inhibition would be caused by carbonylation, since the inhibition was reversed by dialysis. Considering the higher sensitivity of catalase to inhibition induced by soluble extract of tobacco smoke and its important role in peroxide elimination, we conceived that benzo[a]pyrene and other compounds of tobacco smoke extract promote a transient peroxide accumulation which could be one of the factors responsible for the oxidative damage in respiratory tract and other tissues in smokers.