Development of an efficient glucosinolate extraction method.
BACKGROUND
Glucosinolates, anionic sulfur rich secondary metabolites, have been extensively studied because of their occurrence in the agriculturally important brassicaceae and their impact on human and animal health. There is also increasing interest in the biofumigant properties of toxic glucosinolate hydrolysis products as a method to control agricultural pests. Evaluating biofumigation potential requires rapid and accurate quantification of glucosinolates, but current commonly used methods of extraction prior to analysis involve a number of time consuming and hazardous steps; this study aimed to develop an improved method for glucosinolate extraction.


RESULTS
Three methods previously used to extract glucosinolates from brassicaceae tissues, namely extraction in cold methanol, extraction in boiling methanol, and extraction in boiling water were compared across tissue type (root, stem leaf) and four brassicaceae species (B. juncea,S. alba,R. sativus, andE. sativa). Cold methanol extraction was shown to perform as well or better than all other tested methods for extraction of glucosinolates with the exception of glucoraphasatin inR. sativusshoots. It was also demonstrated that lyophilisation methods, routinely used during extraction to allow tissue disruption, can reduce final glucosinolate concentrations and that extracting from frozen wet tissue samples in cold 80% methanol is more effective.


CONCLUSIONS
We present a simplified method for extracting glucosinolates from plant tissues which does not require the use of a freeze drier or boiling methanol, and is therefore less hazardous, and more time and cost effective. The presented method has been shown to have comparable or improved glucosinolate extraction efficiency relative to the commonly used ISO method for major glucosinolates in the Brassicaceae species studied: sinigrin and gluconasturtiin inB. juncea; sinalbin, glucotropaeolin, and gluconasturtiin inS. alba; glucoraphenin and glucoraphasatin inR. sativus; and glucosatavin, glucoerucin and glucoraphanin inE. sativa.
Department of Biology, University of York, Wentworth Way, York, YO10 5DD UK.
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Doheny-Adams
Department of Biology, University of York, Wentworth Way, York, YO10 5DD UK.
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Redeker
Department of Biology, University of York, Wentworth Way, York, YO10 5DD UK.
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Kittipol
Department of Biology, University of York, Wentworth Way, York, YO10 5DD UK.
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Bancroft
Department of Biology, University of York, Wentworth Way, York, YO10 5DD UK.
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Hartley