Effects of caffeine on oxidant-antioxidant mechanisms in the rat liver

Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid which exists in a variety of foods and drinks. Today caffeine is an everyday regularly consumed substance, coffee, tea, chocolate, coke and some soft drinks contain caffeine. The main aim of our study was to compare potential antioxidant effects in rat liver at 2 different doses of short time period oral caffeine intake. We measured MDA levels, which is a product of lipid peroxidation, in rats? livers that caffeine is given. In addition, to evaluate antioxidant properties of caffeine we investigated enzymatic and non-enzymatic antioxidant systems. We measured SOD, catalase, GPx and GST activities and GSH levels in liver. In our study we used 30 female Wister rats with a mean weight of 250 grams. Rats are equally divided into 3 groups. Group 1 was control. Group 2 received 30mg/kg of caffeine and group 3 received 100mg/kg caffeine (non-toxic high dose) for 14 days (short time period) orally. Our results show that 14-day low dose (30mg/kg) and non-toxic dose (100mg/kg) caffeine usage decreased lipid peroxidation in liver. Antioxidant enzyme activities in rat liver like SOD, catalase, GPx and GST showed statistically significant increase with caffeine intake. Liver glutathione level comparison to control group showed a slight increase but this was not statistically significant. Results from the Spearman analysis showed a strong negative correlation and while tissue MDA levels decreased; GPx, GST and SOD activities increased. Tissue GST activity and tissue catalase activity showed a strong positive correlation. Decreased lipid peroxidation and increased antioxidant enzyme activities which improve oxidative stress show that these doses of caffeine may be an antioxidant under the influence of these studies. In our opinion, determining mechanism and antioxidant effect of caffeine at suitable dose requires advanced animal and human studies.