Chlorophylls are important antioxidants found in foods. We explored the mechanisms through which the a and b forms of chlorophyll and of pheophytin (the Mg-chelated form of chlorophyll) reduce oxidation: we used comet assay to measure prevention of H 2 O 2 DNA damage; we tested for quenching of 1,1-diphenyl-2-picrylhydrazyl (DPPH); we measured the ability to chelate Fe(II); and, we tested their ability to prevent formation of thiobarbituric acid reactive substances (TBARS) during Cu-mediated peroxidation of low density lipoprotein (LDL) in a chemical assay. All chlorophylls and pheophytins showed significant dose-dependent activity in the assays, with the pheophytins being the strongest antioxidants. Thus, these chemicals can prevent oxidative DNA damage and lipid peroxidation both by reducing reactive oxygen species, such as DPPH, and by chelation of metal ions, such as Fe(II), which can form reactive oxygen species.

This nationwide survey of nutrition-related knowledge and practices demonstrates the need for nutrition education for physicians. The questionnaire may be a useful instrument for future educational strategies in Taiwan.

Chlorophylls (Chl's) are the most abundant natural plant pigments. Four chlorophyll-related compounds (CRCs), including chlorophyllide a and b (Chlide a and b) and pheophorbide a and b (Pho a and b), were investigated for their antioxidative capacities to protect human lymphocyte DNA from hydrogen peroxide (H(2)O(2)) induced strand breaks and oxidative damage ex vivo. Lymphocytes exposed to H(2)O(2) at concentrations of 10 and 50 microM revealed an increased frequency of DNA single-strand breaks (ssb's; as measured by the comet assay) and also an increased level of oxidized nucleoside (as measured by 8-hydroxydeoxyguanosine, 8-OHdG). All Chl's reduced the level of DNA ssb's and 8-OHdG within human lymphocytes following exposure to 10 microM H(2)O(2). Only Pho a and b were able to decrease DNA ssb's and 8-OHdG following treatment of lymphocytes with 50 microM H(2)O(2), in a concentration-dependent fashion. It was demonstrated herein that Pho a and b were more antioxidative than others. We applied DPPH free-radical scavenge assays in vitro, and got similar results. Pho a and b had higher ability in scavenging capacities than others. We conclude that water-extract Chl's are able to enhance the ability of human lymphocytes to resist H(2)O(2)-induced oxidative damage, especially for Pho a and b.

The aim of this study was to evaluate the effects of purple sweet potato leaves (PSPL) consumption on oxidative stress markers in a healthy, nontrained, young male population after completing a running exercise protocol. A crossover design was applied, with 15 subjects participating in a two-step dietary intervention period. Each subject was given a high- (PSPL group) or low-polyphenol (control group) diet for 7 days with a 14-day washout period. After each dietary intervention period, all subjects performed 1 h of treadmill running at a speed corresponding to 70% of each subject's individual maximal oxygen uptake (Vo(2max)). Blood samples were taken before exercise and at 0, 1, and 3 h after exercise. Compared with the control group, PSPL consumption significantly increased plasma total polyphenols concentration and total antioxidant power (i.e., the ferric-reducing ability of plasma) in the PSPL group. The markers of oxidative damage, plasma TBARS and protein carbonyl, significantly decreased. Plasma IL-6 concentration also decreased. However, no significant difference was found in HSP72 levels between the two groups. These findings indicate that consuming a high-polyphenol diet for 7 days can modulate antioxidative status and decrease exercise-induced oxidative damage and pro-inflammatory cytokine secretion.

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