GLUCOSINOLATE PROFILES IN THE SEED, ROOT AND LEAF TISSUE OF CABBAGE, MUSTARD, RAPESEED, RADISH AND SWEDE

Abstract

Due to the limitations of previous methods for glucosinolate analysis, only fragmentary information has been available on glucosinolate profiles in plant tissues. Using a newly developed high performance liquid chromatography (HPLC) procedure for the separation of desulphoglucosinolates formed by enzymic desulphation of endogenous glucosinolates, the glucosinolate contents in the seed, root and leaf of five cruciferous plants (cabbage, mustard, radish, rapeseed and swede) have been investigated. Identities of peaks in the HPLC chromatograms were confirmed by gas chromatography/mass spectrometry. Major differences between the seed, leaf and root profiles in the same plant were obtained for all five species investigated. Particular attention was directed to the indole glucosinolates, including the recently discovered compounds, 4-hydroxy-3-indolylmethyl glucosinolate and 4-methoxy-3-indolymethyl glucosinolate, for which analytical methods have been previously lacking. These indole glucosinolates were found to have defined distribution patterns: 4-methoxyl-3-indolymethyl glucosinolate and 1-methoxy-3-indolylmethyl glucosinolate were absent in seed material whereas 4-hydroxy-3-indolylmethyl glucosinolate was found in highest concentrations in this tissue. 3-Indolylmethyl glucosinolate was found in low levels in seed but was the dominant indole glucosinolate in the leaf. The possible implications of these findings are discussed. Keywords: Indole glucosinolates, Brassica napus, B. juncea, B. oleracea, B. napobrassica, Raphanus sativus, Cruciferae