Glucosinolates are anionic, hydrophilic plant secondary metabolites that are difficult to separate and purify because of the high polarity and instability of beta-thioglucoside hydroximinosulfates. In the present study, we developed an efficient method for separation and purification of glucosinolates, especially the stereoisomers epiprogoitrin and progoitrin, from Radix isatidis. The method involved the following simple steps: the plant material was first extracted with 70% ethanol; then the extract was purified with acidic alumina to obtain the total glucosinolates; and, finally, the total glucosinolates were separated by reversed phase ODS-BP liquid chromatography to obtain individual glucosinolates. Using this method, 1.04 g progoitrin (1), 3.55 g epiprogoitrin (2), and 1.42 g gluconapin (3), with purity over 98%, were obtained from 3 kg R. isatidis. The result showed that the method was simple and efficient and would serve as a useful reference for the separation of glucosinolates in other plants.
[1]Shanghai Univ Tradit Chinese Med, Sch Pharm, Shanghai 201203, Peoples R China.
[2]Shanghai Univ Tradit Chinese Med, Inst Chinese Mat Med, Shanghai 201203, Peoples R China.
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