['Bacterial lipopolysaccharide (LPS) causes lipid peroxidation (LPO). We have found that LPS induces LPO in vitro, in tissue homogenates in a concentration-dependent manner, the concentration of 400\u2009µg/ml demonstrating the most efficient lipid damaging effect . Both melatonin and its precursor, N-acetylserotonin, must possess antioxidant activities, both in vivo or in vitro, however, following some claims, N-acetylserotonin is a more effective extra- and intracellular antioxidant than melatonin. The aim of our study was to compare the effects of melatonin and N-acetylserotonin on the LPS-induced LPO in vitro.', 'Malondialdehyde (MDA) plus 4-hydroxyalkenal (4-HDA) concentrations were measured as the indices of induced membrane peroxidative damage in brain, liver and kidney homogenates. Both melatonin and N-acetylserotonin were used at increasing concentrations, starting from 0.01-5 mM, together with LPS at one concentration level of 400\u2009µg/ml.', 'In all the examined tissues, LPS stimulated LPO, while both melatonin and N-acetylserotonin decreased LPS-stimulated LPO. Furthermore, the capacity of N-acetylserotonin reducing LPO was higher than that of melatonin.'] Does n-acetylserotonin reduce lipopolysaccharide-induced lipid peroxidation in vitro more effectively than melatonin?