Article

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.

Department of Plant Science and Agricultural Engineering, Universidade de Trás-os-Montes e Alto Douro, Apartado 1013, 5001-911 Vila Real, Portugal.
Journal of Agricultural and Food Chemistry (impact factor: 2.82). 10/2002; 50(21):6239-44. pp.6239-44
Source: PubMed

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.

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Keywords

4-methylsulfinylbutyl glucosinolate
 
Broccoli inflorescences
 
chemoprotective isothiocyanate
 
concordantly greater induction
 
consecutive days postemergence
 
developmental stage
 
glucosinolate content
 
Glucosinolate levels
 
healthy diets
 
higher glucosinolate content
 
highest glucosinolate levels
 
lower temperatures
 
mammalian phase 2 detoxication enzymes
 
Nongerminated seeds
 
parallel induction
 
phase 2 chemoprotective enzymes
 
specific elevations
 
temperature regime
 
vitamin C
 
younger developmental stages