The effects of cranberry juice consumption on antioxidant status and biomarkers relating to heart disease and cancer in healthy human volunteers.

BACKGROUND: Consumption of fruit and vegetables is associated with a decreased risk of heart disease and cancer. This has been ascribed in part to antioxidants in these foods inactivating reactive oxygen species involved in initiation or progression of these diseases. Non-nutritive anthocyanins are present in significant amounts in the human diet. However, it is unclear whether they have health benefits in humans. AIM: To determine whether daily consumption of anthocyanin-rich cranberry juice could alter plasma antioxidant activity and biomarkers of oxidative stress. METHODS: 20 healthy female volunteers aged 18-40 y were recruited. Subjects consumed 750 ml/day of either cranberry juice or a placebo drink for 2 weeks. Fasted blood and urine samples were obtained over 4 weeks. The total phenol, anthocyanin and catechin content of the supplements and plasma were measured. Anthocyanin glycosides were identified by tandem mass spectrometry (MS-MS). Vitamin C, homocysteine (tHcy) and reduced glutathione (GSH) were measured by HPLC. Total antioxidant ability was determined using electron spin resonance (ESR) spectrometry and by the FRAP assay. Plasma total cholesterol, high density lipoprotein (HDL), and low density lipoprotein (LDL) cholesterol and triglycerides (TG) were measured. Glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) activities were measured in erythrocytes. Urine was collected for analysis of malondialdehyde (MDA) by HPLC and 8-oxo-deoxyguanosine (8-oxo-dG) by ELISA. Endogenous and induced DNA damage were measured by single cell gel electrophoresis (SCGE) in lymphocytes. RESULTS: Vitamin C, total phenol, anthocyanin and catechin concentrations and FRAP and ESR values were significantly higher in the cranberry juice compared with the placebo. Cyanidin and peonidin glycosides comprised the major anthocyanin metabolites [peonidin galactoside (29.2%) > cyanidin arabinoside (26.1%) > cyanidin galactoside (21.7%) > peonidin arabinoside (17.5%) > peonidin glucoside (4.1%) > cyanidin glucoside (1.4 %)]. Plasma vitamin C increased significantly (P<0.01) in volunteers consuming cranberry juice. No anthocyanins (plasma) or catechins (plasma or urine) were detectable and plasma total phenols, tHcy,TC,TG,HDL and LDL were unchanged. The antioxidant potential of the plasma, GSH-Px, CAT and SOD activities, and MDA were similar for both groups. Supplementation with cranberry juice did not affect 8-oxo-deoxyguanosine in urine or endogenous or H(2)O(2)-induced DNA damage in lymphocytes. CONCLUSIONS: Cranberry juice consumption did not alter blood or cellular antioxidant status or several biomarkers of lipid status pertinent to heart disease. Similarly, cranberry juice had no effect on basal or induced oxidative DNA damage. These results show the importance of distinguishing between the in vitro and in vivo antioxidant activities of dietary anthocyanins in relation to human health.

Long-term homocysteine exposure induces alterations in spatial learning, hippocampal signalling and synaptic plasticity.

Abnormally high levels of homocysteine (HCY) have been linked to neurodegenerative diseases, but it remains unclear whether this is the cause or effect of degenerative processes. Here, we investigated the effects of prolonged HCY exposure on cognitive abilities and physiological parameters by injecting rats daily with either 20 or 200 mg/kg HCY over a period of up to 14 weeks. Notwithstanding a significant weight reduction in the 200 mg HCY group, HCY-exposed animals did not show a behavioural deficit when tested repeatedly (in weeks 1, 3, 5, 7 and 13) in a reference memory version of the water maze. Unexpectedly, some improvement in repeated reversal learning was observed in HCY exposed animals compared to controls. Pre-treatment with HCY for 3 weeks before water maze training did not uncover any cognitive alterations. Increased plasma concentrations of HCY were revealed only for the 200 mg HCY group after 14 weeks of injections, but no evidence for DNA damage was obtained. Immunocytochemically, HCY was detected in the brain after 14 weeks of treatment (both 20 and 200 mg/kg), but not after 5 weeks. Bidirectional changes in basic synaptic transmission and long-term potentiation of hippocampal CA1 pyramidal cells were observed at 5, 7 and 14 weeks in both HCY groups, indicative of complex, multifactorial time- and concentration-dependent changes. Overall, it is concluded that healthy adult rats are able to cope with continuous exposure to HCY. While HCY affects growth and neuronal excitability, this does not precipitate into an immediate impairment of cognitive function.

Cryopreserved versus freshly isolated lymphocytes in human biomonitoring: endogenous and induced DNA damage, antioxidant status and repair capability.

Lymphocytes are routinely used in human biomonitoring to assess the potential toxic and cytoprotective effects of diet on both DNA damage and repair and, by implication, health. Logistically, samples may require to be cryopreserved and stored. How this affects cells used in human biomonitoring is often not considered. In this study we have evaluated the influence of cryopreservation on endogenous and induced DNA strand breakage, altered bases (oxidized purines, oxidized pyrimidines and misincorporated uracil), antioxidant capacity and DNA repair capability in human peripheral blood lymphocytes. Neither isolation nor freezing increased DNA strand breakage above endogenous levels found in freshly isolated human lymphocytes. Oxidized bases (both pyrimidines and purines) and misincorporated uracil, were similar for fresh and frozen lymphocytes. Fresh and frozen lymphocytes responded almost identically to hydrogen peroxide. Quercetin-mediated cytoprotection against hydrogen peroxide-induced strand breakage was maintained in cryopreserved lymphocytes after short-term (24 h) and longer term (2 months) storage compared with freshly isolated and treated cells. Hydrogen peroxide-induced DNA strand breakage was repaired in fresh lymphocytes. Cryopreserved lymphocytes were unable to repair oxidant-induced DNA strand breaks. Frozen human lymphocytes can therefore be successfully used for most aspects of DNA damage biomonitoring, but not for repair.