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Lipid peroxidation is a part of normal metabolism that may cause biological molecule damage leading to the formation of several specific metabolites that include aldehydes of variable chains, such as malondialdehyde (MDA). These biological effects are controlled in vivo by a wide spectrum of enzymatic and non-enzymatic defense mechanisms among which catalase (CAT) is considered as an important regulator of oxidative stress. The present study aimed to investigate the possible relationship between the temporal patterns of the formation of MDA and the activity of CAT in the erythrocytes of mice. Twenty-four-hour studies were performed on male Swiss albino mice, 12 weeks old, synchronized to a 12:12 light: dark cycle for 3 weeks. Different and comparable groups of animals ( n = 10) were sacrificed at an interval of 4 hours (1, 5, 9, 13, 17, and 21 hours after light onset (HALO)). The levels of erythrocyte MDA concentration and CAT activity both significantly (analysis of variance: F = 6.4, P < 0.002) varied according to the time of sampling under non-stressed conditions. The characteristics of the waveform describing the temporal patterns differed between the two studied variables, e.g. MDA content showing one peak (≅21 HALO) and CAT activity showing three peaks (≅9, 17, and 21 HALO). Cosinor analysis revealed a significant (adjusted Cosinor: P ≤ 0.018) circadian (τ ≅ 24 hours) rhythm in MDA level and no statistically significant rhythmicity in CAT activity. The differences and the absence of correlation between the curve patterns of erythrocyte MDA content and CAT activity under physiological conditions are hypothesized to explain that variation in lipid peroxidation may depend on several factors. Moreover, the identification of peak/trough levels of MDA accumulation in erythrocytes may reflect the degree of oxidative stress in these blood cells. In addition, the observed significant time-of-day effect suggests that, in both clinical and scientific settings, appropriate comparison of MDA production and CAT activity levels can only be achieved on data obtained at the same time of day. [ABSTRACT FROM AUTHOR]

We investigated the dosing-time dependency of acute resveratrol administration on lipoperoxidation level found in the heart, liver and kidney of male rats synchronized with a 12-h dark-light cycle. Resveratrol was administered by the i.p. route at the middle of the dark (6 h after dark onset, HADO) or light span (18 HADO) and thiobarbituric acid reactive species (TBARS) measured 4 h later at 10 and 22 HADO, respectively. Basal TBARS levels in the three organs were higher during the night span when compared to day span. Resveratrol effect on tissues TBARS was also dosing-time dependent. When administered during the dark phase, resveratrol decreased TBARS levels whereas at the light span, the polyphenol increased TBARS in the three organs. Resveratrol behaved as an antioxidant during the dark span and as a pro-oxidant during the light span. These data suggested a day/night rhythm in basal lipoperoxidation and in resveratrol antioxidant effect. [ABSTRACT FROM AUTHOR]