Glucosinolate Accumulation and Hydrolysis in Leafy Brassica Vegetables Are Influenced by Leaf Age

The health-beneficial effects of Brassica vegetablesare mainly attributed to their high contents of glucosinolates andthe products of their hydrolysis, especially isothiocyanates. Distributionof glucosinolates across plant organs can strongly vary. Here, weinvestigated the effect of leaf age on glucosinolate accumulationand hydrolysis in two leafy Brassica vegetables,pak choi and giant red mustard. We also evaluated the activity ofthe hydrolyzing enzyme myrosinase across the leaves. Finally, we assessedwhether glucosinolates are transported from older leaves to youngerleaves. Young leaves of both species contained more than 3-fold moreglucosinolates than older ones. Accordingly, more isothiocyanateswere released in the young leaves. Myrosinases fully hydrolyzed allof the amounts of glucosinolates regardless of the leaf age. Moreover,older leaves were observed to supply younger leaves with glucosinolates.Thus, this study suggests that consumers can improve the nutritionalvalue of food by incorporating young leaves of leafy Brassicas in their diet.

Automated summary

Leaf age significantly affects the accumulation and hydrolysis of glucosinolates and their hydrolysis products in two leafy Brassica vegetables. Young leaves contain more than 3-fold more glucosinolates and release more isothiocyanates compared to older ones. Myrosinases hydrolyze all amounts of glucosinolates regardless of leaf age. Moreover, older leaves supply younger leaves with glucosinolates. Therefore, incorporating young leaves of leafy Brassicas in the diet can enhance the nutritional value of food.