Myrosinase Compatible Simultaneous Determination of Glucosinolates and Allyl Isothiocyanate by Capillary Electrophoresis Micellar Electrokinetic Chromatography (CE-MEKC).
BACKGROUND
The functional food Cruciferous vegetables contain glucosinolates which are decomposed by the myrosinase enzyme upon tissue damage. The isothiocyanates are the most frequent decomposition products. Because of their various bioactivities, these compounds and the myrosinase is of high interest to many scientific fields.


OBJECTIVE
Development of a capillary electrophoresis method capable of myrosinase-compatible, simultaneous quantification of glucosinolates and isothiocyanates.


METHODS
Capillary electrochromatography parameters were optimised, followed by optimisation of a myrosinase-compatible derivatisation procedure for isothiocyanates. Vegetable extracts (Brussels sprouts, horseradish, radish and watercress) were tested for myrosinase activity, glucosinolate content and isothiocyanate conversion rate. Allyl isothiocyanate was quantified in some food products.


RESULTS
The method allows quantification of sinigrin, gluonasturtiin and allyl isothiocyanate after myrosinase compatible derivatisation in-vial by mercaptoacetic acid. The chromatograhpic separation takes 2.5 min (short-end injection) or 15 min (long-end injection). For the tested vegetables, measured myrosinase activity was between 0.960-27.694 and 0.461-26.322 µmol/min/mg protein, glucosinolate content was between 0-2291.8 and 0-248.5 µg/g fresh weight for sinigrin and gluconastrutiin, respectively. The possible specificity of plants to different glucosinolates was also shown. Allyl isothiocyanate release rate was different in different vegetables (73.13 - 102.13%). The method could also be used for quantification of allyl isothiocyanate from food products.


CONCLUSIONS
The presented capillary electrophoresis method requires a minimal amount of sample and contains only a few sample preparation steps, and can be used in several applications (glucosinolate determination, myrosinase activity measurement, isothiocyanate release estimation). Copyright © 2016 John Wiley & Sons, Ltd.
Department of Botany, Division of Pharmacognosy, University of Debrecen, Egyetem tér 1, H-4010, Debrecen, Hungary.
Sándor
http://orcid.org/0000-0001-9776-0249
S
Gonda
Department of Organic Chemistry, Division of Instrumental Analysis, University of Debrecen, Egyetem tér 1, H-4010, Debrecen, Hungary.
Attila
A
Kiss-Szikszai
Department of Botany, Division of Pharmacognosy, University of Debrecen, Egyetem tér 1, H-4010, Debrecen, Hungary.
Zsolt
Z
Szűcs
Department of Botany, Division of Pharmacognosy, University of Debrecen, Egyetem tér 1, H-4010, Debrecen, Hungary.
Nhat Minh
NM
Nguyen
Department of Botany, Division of Pharmacognosy, University of Debrecen, Egyetem tér 1, H-4010, Debrecen, Hungary.
Gábor
G
Vasas
D031215:Armoracia / Q000737:chemistry / Q000201:enzymology; D001937:Brassica / Q000737:chemistry / Q000201:enzymology; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods*; D005961:Glucosinolates / Q000032:analysis* / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000032:analysis* / Q000378:metabolism; D017879:Isothiocyanates / Q000032:analysis* / Q000378:metabolism; D015394:Molecular Structure; D031223:Nasturtium / Q000737:chemistry / Q000201:enzymology; D010936:Plant Extracts / Q000737:chemistry*; D031224:Raphanus / Q000737:chemistry / Q000201:enzymology; D012680:Sensitivity and Specificity; D013997:Time Factors; D014675:Vegetables / Q000737:chemistry* / Q000201:enzymology
D005961:Glucosinolates; D017879:Isothiocyanates; D010936:Plant Extracts; C010330:sinigrin; C004471:allyl isothiocyanate; D006026:Glycoside Hydrolases; C022739:thioglucosidase
Brassicaceae vegetables; Myrosinase assay; allyl isothiocyanate; in-vial derivatisation; phenethyl isothiocyanate