Oxidative DNA Damage In Lymphocytes Research Articles

Fruit juice consumption modulates antioxidative status, immune status and DNA damage

Polyphenolic compounds exert a variety of physiological effects in vitro including antioxidative, immunomodulatory and antigenotoxic effects. In a randomized crossover study in healthy men on a low-polyphenol diet, we determined the effects of 2 polyphenol-rich juices (330 ml/d) supplemented for 2 weeks on bioavailability of polyphenols, markers of antioxidative and immune status, and reduction of DNA damage. Juices provided 236 mg (A) and 226 mg (B) polyphenols with cyanidin glycosides (A) and epigallocatechin gallate (B) as major polyphenolic ingredients. There was no accumulation of plasma polyphenols after two weeks of juice supplementation. In contrast, plasma malondialdehyde decreased with time during juice interventions. Moreover, juice consumption also increased lymphocyte proliferative responsiveness, with no difference between the two juices. Interleukin-2 secretion by activated lymphocytes and the lytic activity of natural killer cells were significantly increased by both juices. Juice intervention had no effect on single DNA strand breaks, but significantly reduced oxidative DNA damage in lymphocytes. A time-delay was observed between the intake of fruit juice and the reduction of oxidative DNA damage and the increase in interleukin-2 secretion. We conclude that consumption of either juice enhanced antioxidant status, reduced oxidative DNA damage and stimulated immune cell functions. However, fruit juice consumption for 2 weeks did not result in elevated plasma polyphenols in subjects after overnight fasting. Further studies should focus on the time-delay between juice intake and changes in measured physiological functions, as well as on active polyphenolic metabolites mediating the observed effects.

Inhibitory effect of Eucommia ulmoides Oliv. on oxidative DNA damage in lymphocytes induced by H2O2.

This study used the alkaline single cell gel electrophoresis assay (comet assay) to investigate the effect of water extracts of roasted cortex and leaves from Du-zhong on DNA damage in lymphocytes induced by H(2)O(2). The results showed that the DNA damage in human lymphocytes increased with an increase in the concentration of H(2)O(2) (0-200 micro;M), but that the water extracts from Du-zhong (0-2 g l(-1)) only slightly affected DNA damage. The inhibitory effect of leaf extract on DNA damage induced by H(2)O(2) in lymphocytes was more significant (P<0.05) than that of roasted cortex. Leaf extract showed a rather significant inhibitory effect in a concentration-dependent manner. At a concentration of 2 g l(-1), the leaf extract inhibited 37.9% DNA oxidative damage in human lymphocytes. In order to elucidate the mechanism of the leaf extract suppression effect on DNA damage induced by H(2)O(2) in lymphocytes, an experiment was divided with six groups (A-F). Group A was used to evaluate the repair ability of the leaf extract for DNA damage; Group B was employed to determine the scavenging ability on H(2)O(2); and Group C was studied to assess the ability of leaf extract to increase the defense capability. Groups D-F were negative controls and blank. The results showed that group B had the best inhibitory effect. Also, leaf extract had significant ability to scavenge H(2)O(2) in an in vitro HRP-phenol red test. Thus, it appears that H(2)O(2) scavenging potency may be the major mechanism whereby leaf extract inhibits oxidative DNA damage induced by H(2)O(2).

Plasma antioxidants and oxidative DNA damage in lymphocytes from normal aged people and Alzheimer disease patients

Plasma antioxidants and oxidative DNA damage in lymphocytes from normal aged people and Alzheimer disease patients

Effects of a soy milk supplement on plasma cholesterol levels and oxidative DNA damage in men--a pilot study.

Phytoestrogens are a major component of Asian diets and may be protective against certain hormone-dependent cancers (breast and prostate) and coronary heart disease. They may also have antioxidant function in scavenging potentially harmful free radicals and thus decreasing oxidative attack on DNA. A pilot study to determine the effects of a phytoestrogen supplement, in the form of soy milk, on plasma LDL and HDL cholesterol levels and DNA damage in men. Ten healthy men participated in the study and were assigned to one of three groups consuming 1 litre of either soy milk, rice dream (vegetable protein control) or semi-skimmed cow's milk (animal protein control) each day for 4 weeks. The soy supplement caused significant increases in plasma genistein and daidzein concentrations despite considerable inter-individual variation (P < 0.001). Supplementation with soy resulted in a decrease in oxidative damage to DNA bases detected using the comet assay compared with controls (P < 0.05). However, there was no significant effect of the soy supplement on plasma cholesterol or triglyceride levels in comparison with control groups. A 4 week soy milk supplementation in healthy volunteers does not alter serum cholesterol levels but can have a protective effect against oxidative DNA damage in lymphocytes.

Glutathione and ascorbate are negatively correlated with oxidative DNA damage in human lymphocytes.

Intracellular antioxidants, glutathione and ascorbate, and two molecular markers of oxidative DNA damage, 5-hydroxy-2'-deoxycytidine (5-OH-dCyd) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo), were measured in lymphocytes from 105 healthy volunteers. The analysis of 5-OH-dCyd and 8-oxo-dGuo was carried out by HPLC with electrochemical detection such that both compounds were detected on the same chromatography run. There was no significant difference in oxidative DNA damage when the extraction of DNA from cells using phenol was carried out under anaerobic conditions or in the presence of metal ion chelators. This indicates that auto-oxidation of DNA during sample preparation was minimal. Using the above methods, the average level of oxidative DNA damage in lymphocytes was 2.9 +/- 1.4 for 5-OH-dCyd and 4.5 +/- 1.8 for 8-oxo-dGuo lesions per 10(6) dGuo (n = 105). It is unlikely that artifactual oxidation contributed to the observed damage because the level of 5-OH-dCyd was comparable with that of 8-oxo-dGuo in lymphocyte DNA, whereas 8-oxo-dGuo outnumbers 5-OH-dCyd by a ratio of >5:1 when DNA is exposed to various oxidants, including ionizing radiation or Fenton reagents. Rather, the nearly equal levels of 5-OH-dCyd and 8-oxo-dGuo in cellular DNA implies that 8-oxo-dGuo may be more efficiently removed by DNA repair. Finally, and most importantly, the correlation of our endpoints revealed that the naturally occurring level of intracellular antioxidants was negatively correlated to the level of oxidative DNA damage with the strongest correlation observed for glutathione and 8-oxo-dGuo (r = -0.36; P < 0.001). These results strongly suggest that intracellular glutathione and ascorbate protect human lymphocytes against oxidative DNA damage.

Induction of oxidative DNA damages and enhancement of cell proliferation in human lymphocytes in vitro by butylated hydroxyanisole.

The food additive butylated hydroxyanisole (BHA) has been shown to induce gastrointestinal hyperplasia in rodents by an unknown mechanism. The relevance of this observation for human risk assessment is not clear. We therefore analysed the effect of BHA and its primary metabolites tert-butylhydroquinone (TBHQ) and tert-butylquinone (TBQ) on 8-oxo-deoxyguanosine formation and labelling induces in human lymphocytes in vitro. Analysis of culture medium and cell lysate fractions after administration of BHA or metabolites of BHA revealed that BHA and TBHQ undergo biotransformation in whole blood cultures. Moreover, TBQ can be reduced to TBHQ. While in cultures treated with BHA 50-60% of the dose administered was recovered, a much lower dose recovery was found in cultures treated with either TBHQ or TBQ. This indicates a considerable binding of these compounds to macromolecules. BHA and TBHQ, as well as TBQ, induced a dose-dependent increase in cell proliferation of phytohaemagglutinin-stimulated lymphocytes, 50 microM being the optimal dose. Since BHA is metabolized to TBHQ, it is not clear which compound is responsible for the proliferation enhancing effects observed in culture. Inhibition of IBHQ metabolism to its semiquinone radical by acetylsalicylic acid (ASA) reduced the increase in labelling indices induced by TBHQ. This indicates that this metabolic pathway is involved in the enhancement of cell proliferation induced by the hydroquinone. HPLC-ECD analysis of oxidative DNA damage in lymphocytes exposed to 10, 50 and 100 microM BHA, TBHQ or TBQ respectively showed that BHA was not capable of inducing oxidative DNA damage to a significant degree. TBQ and, in particular, TBHQ at a dose of 50 microM (the optimal dose for induction of cell proliferation), however, increased lymphocyte 7-hydroxy-8-oxo-2'-deoxyguanosine formation by 320 and 680% respectively. Inhibition of prostaglandin H synthase by ASA in cultures treated with TBHQ decreased the oxidation ratio significantly, confirming the significance of this enzyme system in the mechanism of toxicity of BHA.