Determination of Cobalt(II)-Hydrogen Peroxide-Induced DNA Oxidative Damage and Preventive Antioxidant Activity by CUPRAC Colorimetry

Studies have demonstrated that the induction of oxidative stress may be involved in oxidative DNA damage. The present study examined and assessed the hydrogen peroxide (H2O2)-mediated DNA damage in human tumor KB cells and also assessed the ability of Moringa oleifera leaf extracts to inhibit the oxidative damage. H2O2 imposed a stress on the membrane lipids which was quantified by the extent of thiobarbituric acid reactive substances (TBARS) formed. The leaf extracts caused a very significant inhibition of the extent of LPO formation and enhanced the activity of antioxidative enzymes such as superoxide dismutase (SOD) and catalase (CAT) in KB cells. The comet assay was employed to study the DNA damage and its inhibition by the leaf extracts. H2O2 caused a significant increase in the number of cells bearing comets, resulting in significant DNA damage. The leaf extracts significantly reduced the incidence of comets in the oxidant stressed cells. The extent of cytotoxicity of H2O2 in the presence and the absence of leaf extracts studied in KB tumor cells by the MTT assay showed that H2O2 caused a marked decrease in the viability of KB cells where as the leaf extracts effectively increased the viability of assaulted KB cells. The observed cytoprotective activity is probably due to the antioxidant properties of its constituents, mainly phenolics. Total phenolics showed higher correlation with antioxidant activity. The leaf extracts showed higher antioxidant activity than the reference compound. These results suggest that the inhibition by the leaf extracts on oxidative DNA damage could be attributed to their free radical scavenging activities and the effect evidenced in KB cells can be in part correlated to a modulation of redox-sensitive mechanisms.

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Relevance of apple consumption for protection against oxidative damage induced by hydrogen peroxide in human lymphocytes

British Journal Of Nutrition ◽

10.1017/s0007114507665192 ◽

2007 ◽

Vol 97 (5) ◽

pp. 921-927 ◽

Cited By ~ 23

Author(s):

Francesca Maffei ◽

Andrea Tarozzi ◽

Fabio Carbone ◽

Alessandra Marchesi ◽

Silvana Hrelia ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Antioxidant Activity ◽

Oxidative Damage ◽

Human Lymphocytes ◽

Apple Fruit ◽

Significant Inhibition ◽

Total Antioxidant Activity ◽

Plasma Samples ◽

Total Antioxidant ◽

Ros Formation

In a single-dosing crossover study, we investigated the ability of apple fruit consumption to protect human lymphocytes against peroxide-induced damage to DNA. Six healthy, non-smoking male volunteers were placed for 2 d on an antioxidant-poor (AP) diet. After 48 h of AP diet, the volunteers were required to consume a homogenate obtained from 600 g of red delicious unpeeled apples or water (500 ml); blood samples were collected 0, 3, 6 and 24 h post-consumption. To evaluate whether the apple intake was sufficient to restore resistance of DNA to oxidative damage, for each subject at any time point the plasma total antioxidant activity, reactive oxygen species (ROS) formation and induction of micronuclei (MN) in isolated lymphocytes following hydrogen peroxide (H2O2) treatment were measured. Results indicated a significant inhibition (58 %, P < 0·05) of H2O2-induced MN frequency in the plasma samples collected at 3 h after apple consumption, as compared with plasma samples collected at 0 h (4·17 (sd 1·83) v. 9·85 (sd 1·87) MN/1000 binucleated (BN) cells, respectively). A gradual return towards the value observed at 0 h was recorded starting from 6 to 24 h. MN frequency induced by H2O2 was significantly influenced by plasma total antioxidant activity (r = –0·95, P < 0·05) and by the increase of intracellular ROS formation (r = 0·88, P < 0·05). These findings suggest that the consumption of whole apple provides a useful dietary source of active scavengers to protect cells and tissue from oxidative stress and related DNA injury.

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