Kinetics of Brassicaceae glucosinolates sinigrin, sinalbin, and glucolimnanthin hydrolysis by myrosinase isoenzymes for biopesticide development

Abstract

Biopesticides from Brassicaceae plants can reduce the impact of synthetic pesticides by providing an environmentally sustainable yet economically sound pest control option. Meals of Brassicaceae oilseed crops are by-products of oil extraction, that are both affordable and easily accessible. Pesticidal activity of Brassicaceae oilseed meals is attributed to glucosinolates that upon hydrolysis by myrosinase produce pesticidal isothiocyanates. Here we present kinetics analysis of extracts from Sinapis alba and Brassica juncea containing active myrosinase isoenzymes toward the endogenous and exogenous glucosinolates with the goal of improving the biopesticide formulation. Based on Michaelis–Menten kinetics, S. alba myrosinase had 10–20 times higher activity toward endogenous sinalbin and exogeneous sinigrin and glucolimnanthin glucosinolates. B. juncea myrosinase exhibited Michaelis–Menten kinetics with endogenous sinigrin and exogeneous glucolimnanthin but not with exogeneous sinalbin. These findings indicate the preferential activity of isoenzymes toward glucosinolates and possibility of using an exogenous myrosinase for improving the release rate of pesticidal isothiocyanates in Brassicaceae biopesticides.