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Micellar electrokinetic capillary chromatography—Synchronous monitoring of substrate and products in the myrosinase catalysed hydrolysis of glucosinolates

Bellostas, Natalia; Sorensen, Jens Christian and Sorensen, Hilmer (2006) Micellar electrokinetic capillary chromatography—Synchronous monitoring of substrate and products in the myrosinase catalysed hydrolysis of glucosinolates. Journal of Chromatography A. [In Press]

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Summary

A micellar electrokinetic capillary chromatography (MECC) method has been developed for monitoring the myrosinase catalysed hydrolysis of 2-hydroxy substituted glucosinolates and the simultaneous formation of the corresponding degradation products (oxazolidine-2-thiones (OZTs) and nitriles). Glucosibarin ((2R)-2-hydroxy-2-phenylethylglucosinolate) was chosen as the model glucosinolate owing to the difficulties in determining hydrolysis rates of this type of substrates in traditional UV-assays. The method was afterwards validated with glucobarbarin ((2S)-2-hydroxy-2-phenylethylglucosinolate) and progoitrin ((2R)-2-hydroxybut-3-enylglucosinolate). Aromatic glucosinolates without a 2-hydroxy group in their side chains, such as glucotropaeolin (benzylglucosinolate) and gluconasturtiin (phenethylglucosinolate) were also tested. Formation of the glucosinolate
hydrolysis products was monitored simultaneously at 206 nm and 230 nm. This allowed estimation of the extinction coefficient of the OZT derived from glucosibarin, which was found to be 18,000M−1 cm−1 and 12,000M−1 cm−1 at 206 nm and 230 nm, respectively. The developed method has limit of detection of 0.04mM and 0.06mM and limit of quantification of 0.2mM and 0.3mM for the glucosibarin derived OZT and nitrile, respectively. Linearity of the glucosinolate concentration was examined at six concentration levels from 2.5mMto 100mMand at 206 nm a straight line (R2 = 0.9996) was obtained. The number of theoretical plates (N) at the optimal system conditions was 245,000 for the intact glucosibarin,
264,000 for the OZT and 252,000 for the nitrile.


EPrint Type:Journal paper
Keywords:Glucosinolates; Myrosinase; Nitriles; OZTs; MECC; Synchronous method
Subjects: Crop husbandry > Crop health, quality, protection
Food systems > Food security, food quality and human health
Research affiliation: Denmark > SOAR - Research School for Organic Agriculture and Food Systems
Related Links:http://www.kursus.kvl.dk/soar/
Deposited By: Bellostas Muguerza, Natalia
ID Code:9260
Deposited On:18 Sep 2006
Last Modified:12 Apr 2010 07:34
Document Language:English
Status:In Press
Refereed:Peer-reviewed and accepted

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