The current understanding of the complex role of ROS in the organism and pathological sequelae of oxidative stress points to the necessity of comprehensive studies of antioxidant reactivities and interactions with cellular constituents. Studies of antioxidants performed within the COST B-35 action has concerned the search for new natural antioxidants, synthesis of new antioxidant compounds and evaluation and elucidation of mechanisms of action of both natural and synthetic antioxidants. Representative studies presented in the review concern antioxidant properties of various kinds of tea, the search for new antioxidants of herbal origin, modification of tocopherols and their use in combination with selenium and properties of two promising groups of synthetic antioxidants: derivatives of stobadine and derivatives of 1,4-dihydropyridine.

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The brain is exceptionally susceptible to oxidative stress that may be caused by xenobiotics such as ethanol. Alcohol metabolism is accompanied by enhanced free radical formation and a decrease in antioxidant abilities. However, L-carnitine appears to have antioxidant properties and the ability to regulate ethanol metabolism. The present study was designed to estimate the effect of L-carnitine on the antioxidant capacity of the rat brain and blood serum. For 5 weeks during the study, L-carnitine was given to rats in the amount of 1.5 g/1 l of drinking water, and from the second week the rats were intragastrically treated with ethanol. A significant decrease in the activity of antioxidant enzymes (Cu,Zn-SOD, GSH-Px, GSSG-R and CAT) and in the level of non-enzymatic antioxidants (vitamin C, E, A, GSH and GSH-t) as well as a significant increase in the level of GSSG in the brain and blood serum of ethanol intoxicated rats have been demonstrated. It has also been shown that alcohol caused a significant increase in the level of lipid peroxidation products-lipid hydroperoxides, malondialdehyde and 4-hydroxynonenal-and an increase in dityrosine, as well as a decrease in tryptophan-markers of protein oxidative modifications. The administration of L-carnitine to ethanol intoxicated rats partially normalized the activity of the examined enzymes and the level of the above non-enzymatic antioxidants. Moreover, L-carnitine significantly protects lipids and proteins against oxidative modifications. In conclusion, it has been proved that L-carnitine protects rat brain and blood serum against oxidative stress formation and it is possible that this small molecular amine has a similar beneficial effect on the human CNS.

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