Influence of temperature and ontogeny on the levels of glucosinolates in broccoli (Brassica oleracea Var. italica) sprouts and their effect on the induction of mammalian phase 2 enzymes.
ABSTRACT Broccoli inflorescences have been recognized as components of healthy diets on the basis of their high content of fiber, vitamin C, carotenoids, and glucosinolates/isothiocyanates. Broccoli sprouts have been recently shown to have high levels of glucoraphanin (4-methylsulfinylbutyl glucosinolate), the precursor of the chemoprotective isothiocyanate, sulforaphane. This study evaluated the effects of temperature and developmental stage on the glucosinolate content of broccoli sprouts. Seedlings cultivated using a 30/15 degrees C (day/night) temperature regime had significantly higher glucosinolate levels (measured at six consecutive days postemergence) than did sprouts cultivated at lower temperatures (22/15 and 18/12 degrees C; p < 0.001). Both higher (33.1 degrees C) and lower (11.3 degrees C) constant temperatures induced higher glucosinolate levels in sprouts grown to a uniform size. Glucosinolate levels were highest in cotyledons and lowest in roots of sprouts dissected both early and late in the 11 day developmental span investigated. Nongerminated seeds have the highest glucosinolate levels and concordantly greater induction of mammalian phase 2 detoxication enzymes. Levels decline as sprouts germinate and develop, with consistently higher glucosinolate content in younger developmental stages, independent of the temperature regime. Temperature stress or its associated developmental anomalies induce higher glucosinolate levels, specific elevations in glucoraphanin content, and parallel induction of phase 2 chemoprotective enzymes.
Article: Ingestion of broccoli sprouts does not improve endothelial function in humans with hypertension.[show abstract] [hide abstract]
ABSTRACT: Ingestion of glucosinolates has previously been reported to improve endothelial function in spontaneously hypertensive rats, possibly because of an increase in NO availability in the endothelium due to an attenuation of oxidative stress; in our study we tried to see if this also would be the case in humans suffering from essential hypertension. 40 hypertensive individuals without diabetes and with normal levels of cholesterol were examined. The participants were randomized either to ingest 10 g dried broccoli sprouts, a natural donor of glucosinolates with high in vitro antioxidative potential, for a 4 week period or to continue their ordinary diet and act as controls. Blood pressure, endothelial function measured by flow mediated dilation (FMD) and blood samples were obtained from the participants every other week and the content of glucosinolates was measured before and after the study. Measurements were blinded to treatment allocation. In the interventional group overall FMD increased from 4% to 5.8% in the interventional group whereas in the control group FMD was stable (4% at baseline and 3.9% at the end of the study). The change in FMD in the interventional group was mainly due to a marked change in FMD in two participants while the other participants did not have marked changes in FMD. The observed differences were not statistically significant. Likewise significant changes in blood pressure or blood samples were not detected between or within groups. Diastolic blood pressure stayed essentially unchanged in both groups, while the systolic blood pressure showed a small non significant decrease (9 mm Hg) in the interventional group from a value of 153 mm Hg at start. Daily ingestion of 10 g dried broccoli sprouts does not improve endothelial function in the presence of hypertension in humans. Clinicaltrials.gov NCT00252018.PLoS ONE 01/2010; 5(8):e12461. · 4.09 Impact Factor
Article: Seasonal effects on bioactive compounds and antioxidant capacity of six economically important brassica vegetables.[show abstract] [hide abstract]
ABSTRACT: Research on natural and bioactive compounds is increasingly focused on their effects on human health, but there are unexpectedly few studies evaluating the relationship between climate and natural antioxidants. The aim of this study was analyze the biological role of six different Brassica vegetables (Brassica oleracea L. and Brassica rapa L.) as a natural source of antioxidant compounds. The antioxidant activity may be assigned to high levels of L-ascorbic acid, total phenolics and total flavonoids of each sample. The climate seasons affected directly the concentration of bioactive components and the antioxidant activity. Broccoli inflorescences and Portuguese kale showed high antioxidant activity in Spring-Summer whilst turnip leaves did so in Summer-Winter. The Brassica vegetables can provide considerable amounts of bioactive compounds and thus may constitute an important natural source of dietary antioxidants.Molecules 01/2011; 16(8):6816-32. · 2.39 Impact Factor