Biotransformation of Glucosinolates Epiprogoitrin and Progoitrin to (R)- and (S)-Goitrin in Radix isatidis

Radix isatidis is an important traditional Chinese medicine with antiviral efficacy. (R)- and (S)-Goitrin are its main bioactive constituents in the 2010 edition of the Chinese Pharmacopoeia. (R)- and (S)-Goitrin are the breakdown products of epiprogoitrin and progoitrin from R. isatidis. The biotransformation of glucosinolates epiprogoitrin and progoitrin to (R)- and (S)-goitrin, however, is still unclear. In the current paper, the biotransformation of glucosinolates was studied. First, the high-performance liquid chromatography methods to analyze glucosinolates and their breakdown products were developed. Then, the biotransformation of individual glucosinolates such as epiprogoitrin and progoitrin was investigated under different pH conditions. Lastly, their biotransformation under five extraction environments was studied. The results showed that (R)- and (S)-goitrin were the most noteworthy breakdown products. Their relative transformation rates were about 70–80%, and the influence of different extraction environments on the transformation rate was not significant. These results would serve as a theoretical basis for industrial production and quality control and would be helpful for further studies on the biotransformation of glucosinolates.