Glucosinolate hydrolysis products from various plant sources: pH effects, isolation, and purification

Glucosinolates are a class of organic anions that can be hydrolyzed either enzymatically with myrosinase or non-enzymatically to form primarily isothiocyanates and/or nitriles. The isolation and purification of these hydrolysis products are of particular interest both for their potential use in organic synthesis and for their biological activities. Methods were developed for the isolation and purification of gram-scale quantities of several ω-(methylthio)alkyl-, ω-(methylsulfinyl)alkyl-, ω-(methylsulfonyl)alkyl-, and substituted benzyl glucosinolate hydrolysis products; the isothiocyanates erucin [1-isothiocyanato-4-(methylthio)butane], iberin [1-isothiocyanato-3-(methylsulfinyl)propane], cheirolin [1-isothiocyanato-3-(methylsulfonyl)propane], lesquerellin [1-isothiocyanato-6-(methylthio)hexane], hesperin [1-isothiocyanato-6-(methylsulfinyl)hexane], sulforaphene [1-isothiocyanato-4-(methylsulfinyl)but-3-ene], 3-methoxybenzyl isothiocyanate, and 4-hydroxybenzyl isothiocyanate; and the nitriles iberverin nitrile [1-cyano-3-(methylthio)propane], erucin nitrile [1-cyano-4-(methylthio)butane], and 3-methoxybenzyl nitrile using defatted seedmeal from several different genera within the crucifer family (Brassicaceae) and meadowfoam family (Limnanthaceae) as the source of parent glucosinolates. The procedures use solvent extraction of autolyzed defatted seedmeals from various plant sources together with variable reaction pHs and solvent partitioning to obtain relatively pure (generally >97%) compounds without the need for chromatographic separation.