Level of glucosinolates in Brassicaceae vegetables harvested during autumn and winter in Japan

Abstract

Brassicaceae vegetables contain glucosinolates, and have been known to contribute to the promotion of health in human beings. The objective of this study was to identify the composition and content of glucosinolates, and to identify the distribution of ω-methylsulfinyl, phenetyl, and indolyl-3-methyl glucosinolates, which are the precursors of isothiocyanates which induce phase Ⅱ enzymes and/or inhibit phase Ⅰ enzymes, in the 15 species of Brassicaceae vegetables which were har vested during autumn and winter in Japan.Glucosinolate profiles were investigated by LC-MS.Twenty-five species of glucosinolates were identified (aliphatic 18, aromatic 3, indole 4). 4-methylsulfinylbutyl glucosinolate was included in broccoli sprouts ( 111.15±15.46μmol・gDW^-1 ), broccoli ( 10.45±5.05 ), cabbage ( 5.05±5.82 ), and rocket salad ( 4.15±1.83 ). 5-methylsulfinylpentyl glucosinolate was included in tur nip leaves ( 2.96±1.39 ) and field mustard ( nabana ) ( 2.10±1.73 ). In watercress, 6-methylsulfinylhexyl ( 2.96±0.98 ), 7-methylsulfinylheptyl ( 25.08±5.20 ), and 8-methylsulfinyloctyl glucosinolate ( 4.24±3.07 ) were included at a higher content than in any other vegetables. Phenethyl glucosinolate was included in many kinds of Blassica vegetables. These were watercress ( 30.03±8.88 ), tur nip rapa ( 5.64±1.86 ) and leaves ( 2.42±0.17 ), field mustard ( 1.73±0.51 ), broccoli sprouts ( 1.47±0.05 ), and komatsuna ( 1.30±1.12 ). Indolyl-3-methyl glucosinolate was included in many vegetables excluding Japanese radish and rocket salad.