Effects of consumption of Brussels sprouts on intestinal and lymphocytic glutathione S-transferases in humans

Abstract

A high intake of glucosinolate-containing cruciferous vege tables, such as Brussels sprouts (Brassica oleraceae), has been linked to a decreased cancer risk, but the underlying mechanism is still unclear. The aim of this study was to reveal possible modulating effects of consumption of Brussels sprouts on duodenal, rectal and lymphocytic (i) glutathione S-transferase (GST) enzyme activity, (ii) GST isozyme levels and (iii) glutathione (GSH) content. Ten healthy non-smoking volunteers were randomly assigned to two groups in a cross-over design. Five persons started on a glucosinolate-free diet (control period), while the other five consumed 300 g/day cooked Brussels sprouts, at the expense of 300 g glucosinolate-free vegetables (sprouts period). After 7 days the regimen was changed for a further week. At the end of both periods blood samples and duodenal and rectal biopsies were taken. Mean GST activity showed marked differences between duodenal, rectal and lymphocytic cytosols (737 ± 54, 321 ± 29 and 154 ± 14 nmol/min/mg protein respectively), but was uninfluenced by the dietary regimen. Isozyme distribution varied greatly between the tissues. In duodenum GST-a, -7C and -[i iso zymes were expressed in considerable amounts (8441 ± 1365,3002 ± 223 and 536 ± 248 ng/mg protein respectively). Rectal biopsies also contained above three GST classes, but here GST-n was the most pronounced expressed isozyme (2849 ± 246) followed by GST-|n (495 ± 242), while GSTa was only present in minor quantities (149 ± 31). In lymphocytes only GST-71; (755 ± 96) and GST-p, (83 ± 54) could be detected. As a result of the dietary regimen rectal GST-a and -71 levels were slightly increased at the end of the sprouts period, by 30 and 15% respectively. GSH contents were uninfluenced by the dietary regimen. In conclusion, consumption of glucosinolate-containing Brussels sprouts for 1 week results in increased rectal GST-a and -tc isozyme levels. We hypothesize that these enhanced detoxification enzyme levels may partly explain the epidemiological association between a high intake of glucosinolates (cruciferous vegetables) and a decreased risk of colorectal cancer.

Watercress supplementation in diet reduces lymphocyte DNA damage and alters blood antioxidant status in healthy adults

“…This observation further supports previous observations from our laboratory (15) that CVs do not exert their protective activity via modulation of SOD or GPX enzyme activity, although Dragsted et al (38) reported that a fruit and vegetable diet (a component of which was CV) did significantly increase GPX activity. Another potential mechanism of the antigenotoxicity observed as a result of watercress supplementation is a change in GST activity, as has been previously observed with brassica vegetables (12,22). However, the effects of watercress on GST activity in the present study and the correlations with GST single nucleotide polymorphisms will be dealt with in a separate article.…”

“…Some of these mechanisms include alterations in the activities of metabolic enzymes (12), resulting in reduced carcinogenicity of dietary or environmental carcinogens in vivo (13), reduction of oxidative DNA damage levels in humans after supplementation with Brussels sprouts (14), and reduced DNA damage in human lymphocytes ex vivo in conditions of increased oxidative stress after supplementation with cruciferous and leguminous sprouts (15). Moreover, in in vitro studies, extracts of Brussels sprouts have been shown to reduce the genotoxic effects of hydrogen peroxide in human lymphocytes (16), and those of cruciferous and leguminous sprouts reduced genotoxic effects of hydrogen peroxide in human colon cancer (HT-29) cell lines (15).…”

Polycyclic aromatic hydrocarbon‐DNA adducts in liver tissues of hepatocellular carcinoma patients and controls

“…Third, in addition to metabolic enzymes, nutritional status might modulate DNA damage 31 and GST levels. 38 A prior report showed that association between smoking-adjusted plasma ␤-carotene levels and PAH-DNA adducts was significant only in those subjects lacking GSTM1. 31 Fourth, the small number of non-HCC controls in our study limited our ability to investigate the impact of genotype, to look at the genotype-adduct association among smokers and the combinatory effect of the 2 polymorphisms on adduct formation.…”

Modulation of Human Glutathione S-Transferases by Polyphenon E Intervention

“…Further studies are needed to determine the human tissue GST-k expression after green tea catechin intervention. Expression of GST-A is also evident in human blood lymphocytes (25). We have measured GST-A levels in lymphocyte lysates semiquantitatively.…”