Glucosinolate-derived amine formation in Brassica oleracea vegetables

Glucosinolates are precursors of bioactive and health-promoting isothiocyanates (ITCs). Upon enzymatic hy-drolysis, Brassica vegetables, such as cabbage, also often yield nitriles and epithionitriles as main products next to ITCs. Here, we show that amines can be additional main enzymatic hydrolysis products of glucosinolates in Brassica vegetables. We propose that a plant endogenous ITC hydrolase (ITCase) is responsible for the enzymatic -like conversion of ITCs to amines in cabbage samples. This ITCase seems to have high activity towards alkenyl ITCs like allyl ITC and lower activity towards methylthioalkyl ITCs, and not to converting methylsulfinylalkyl ITCs like sulforaphane. In contrast, during heat treatment of homogenized cabbage material, methyl-sulfinylalkylamine levels increased by 400 % after 2 h of heating, which is likely due to thermal decomposition of ITCs, whereas alkenyl amine levels did not change due to heat treatment. The results show that amines from glucosinolates are part of the human diet.

Automated summary

Glucosinolates are precursors of isothiocyanates (ITCs). Amines were found to be enzymatic hydrolysis products of glucosinolates in Brassica vegetables. An endogenous ITC hydrolase (ITCase) in the plants is responsible for the conversion of ITCs to amines. The presence of amines from glucosinolates in the human diet was confirmed.