Antioxidant enzymes activity involvement in luteolin-induced human lung squamous carcinoma CH27 cell apoptosis

Luteolin (3′,4′,5,7-tetrahydroxyflavone) is an active constituent of Lonicera japonica (Caprifoliaceae), and has been reported to produce anti-tumor activities. However, the apoptosis-inducing activity of luteolin still remains unknown. Flavonoids have been found to posses prooxidant and antioxidant action. The biological and pharmacological effect of flavonoid may depend upon its behavior as either an antioxidant or a prooxidant. Our experiments found that luteolin-induced CH27 cell apoptosis was accompanied by activation of antioxidant enzymes, such as superoxide dismutase and catalase, but not through the production of reactive oxygen species and disruption of mitochondrial membrane potential. Therefore, the effects of luteolin on CH27 cell apoptosis were suspected to result from the antioxidant rather than the prooxidant action of luteolin.