Extensive epidemiological evidence suggests that carotenoids (including vitamin A), ascorbate (vitamin C), tocols (including vitamin E), and glucosinolate breakdown products exert anticarcinogenic effects in a range of human tissues. Consumption of fresh and processed vegetables with enhanced levels of these phytochemicals could reduce human risk of cancer. The vitamins play a major role as antioxidants, offering protection against cancer by preventing or reversing oxidative damage to DNA and other cellular components. Cruciferous vegetables contain glucosinolates (GSs), which, during mastication, are hydrolyzed by the enzyme myrosinase into bioactive breakdown products (BBPs), including sulforaphane. BBPs appear to induce synthesis of drug metabolism enzymes resulting in increased detoxification rates of carcinogens. This paper describes an interdisciplinary investigation designed to develop vegetable cultivars that offer chemoprotection from cancer at doses commensurate with a normal American diet. Initial work has focused on surveying sweet corn and Brassicae oleraceae germplasm for variation in vitamin and glucosinolate content in conjunction with in vitro and in vivo bioassays to determine which compounds and concentrations optimize chemoprotectant activity. Segregating populations from crosses between sweet corn and Brassica lines that vary in vitamin and GS concentrations will be assayed for chemical content and chemoprotectant activity, and genetically characterized using DNA marker technology to identify and map genes controlling these traits. This information will improve selection methodology in a breeding program aimed to develop brassica and sweet corn germplasm with enhanced cancer chemoprevention.
Turnips (Brassica rapa. subsp. rapa L.) produce glucosinolates (GSLs), thioglucosides whose hydrolyzed derivatives have been shown to provide chemopreventive benefits. Two cultivars of turnips [‘Just Right’ (JR) and ‘Scarlet Queen’ (SQ)] were grown under three different temperature regimes to assess the role of temperature on GSL production in roots and shoots. When compared with low-temperature treatments, high-temperature treatments increased total and individual GSLs in a tissue- and genotype-specific manner. When compared with low-temperature treatments, total GSLs were ≈70% and 130% higher in JR shoots and roots, respectively, grown at high-temperature treatments. High temperatures also increased total GSLs in SQ shoots and roots by ≈80% and 85%, respectively, when compared with low temperatures. Gluconasturtiin (GNS, 2-phenylethyl GSL) concentration was inversely correlated with temperature with high-temperature treatments resulting in 20% and 48% less GNS than low-temperature treatments in JR and SQ roots, respectively. The indolic GSL, 1-methoxyglucobrassicin (1MGB; 1-methoxy-3-ylmethyl GSL), was the root GSL most elevated by increased temperature resulting in a 1000% increase on average in both cultivars between the low- and high-temperature treatments. These results show promise for the use of temperature to enhance the health-promoting properties of turnip because 1MGB has potent chemopreventive effects. Gene expression analysis suggests that some BrMYB transcription factor expression levels are associated with temperature-dependent changes in GSL accumulation; however, this association varies between cultivar and tissue type.
Glucosinolates (GSLs) are thioglucosides with important properties for plant defense and human health. The objective of this study was to quantify yield and GSL concentration in turnip (Brassica rapa subsp. rapa) roots and shoots as influenced by colored plastic mulches. Four turnip cultivars (‘Just Right’, ‘Purple Top’, ‘Royal Crown’, and ‘Scarlet Queen’) were grown over five mulch treatments: white, yellow, silver, red, blue, and a bare soil control in both a May and an August planting in 2006 and 2007. Yield varied by variety; however, there was no consistent relationship between mulch treatment and yield. Glucosinolate concentrations and profiles varied with tissue type, genotype, and environmental factors, including temperature and planting date. Mulch-dependent increases in GSL concentrations were not consistent across tissue types, cultivars, planting dates, and years of the study, possibly as a result of differences in climatic factors and mulch-dependent changes in soil temperature between planting dates and years of the study.
.M. Syed, D.N. Mukhtar, H. 2005 Pomegranate fruit juice for chemoprevention and chemotherapy of prostate cancer Proc. Natl. Acad. Sci. USA 102 14813 14818 Royal Horticultural Society 1966 Color chart Royal
. Gupta, A. Blackwood, M. Stoner, G.D. 2001 Chemoprevention of esophageal tumorigenesis by dietary administration of lyophilized black raspberries Cancer Res. 61 6112 6119 Lewers, K.S. Weber, C.A. 2005 The trouble with genetic mapping of raspberry
carcinogenesis, and for identifying the molecular targets for chemoprevention ( Dhar et al., 2002 ). Antioxidants and extracts of apple peel have been shown to inhibit AP-1 activity in JB6 cells ( Ding et al., 2004 ; Dong et al., 1997a , b ). Therefore, some
detoxification enzymes ( Wattenberg, 1990 ). Previous studies have shown that PEITC provides significant chemoprevention, especially against human prostate cancer ( Powolny et al., 2003 ; Wargovich, 2000 ; Xiao et al., 2003 ). Gluconasturtiin is present in
in USDA food composition data for 43 garden crops, 1950 to 1999 J. Amer. Coll. Nutr. 23 669 682 Galati, G. Teng, S. Moridani, M.Y. Chan, T.S. O'Brien, P.J. 2000 Cancer chemoprevention and apoptosis mechanisms induced by dietary polyphenolics Drug
potential for chemoprevention of Alzheimer's disease ( Heo et al., 2004 ). Currently, there are several commercially available pharmaceutical drugs that contain baicalein and baicalin from Baikal skullcap ( Ciesielska et al., 2002 ), along with many herbal
.A. Munoz, A. Kensler, T.W. 2003 Chemoprevention with chlorophyllin in individuals exposed to dietary aflatoxin Mutat. Res. 523 209 216 Emenhiser, C. Sander, L.C. Schwartz, S.J. 1995