Identification and quantification of antitumor thioproline and methylthioproline in Korean traditional foods by a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry

A liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometric method (LC-APCI-MS/MS) has been developed for the sensitive determination of antitumor thioproline and methylthioproline from fermented foods. Thioproline and methylthioproline were derivatized in one step with ethyl chloroformate at room temperature. These compounds were identified and quantified in various traditional Korean fermented foods by LC-APCI-MS/MS. The concentration range of thioproline of each food was found for doenjang (0.011-0.032 mg/kg), gochujang (0.010-0.038 mg/kg), and ganjang (0.010-0.038 mg/kg). Those of methylthioproline of each food was found for doenjang (0.098-0.632 mg/kg), gochujang (0.015-0.112 mg/kg), and ganjang (0.023-1.468 mg/kg). A prolonged aging time leads to an increase in both the thioproline and methylthioproline contents, suggesting that the storage time plays a key role in the formation of thioproline and methylthioproline in Korean traditional foods. The results here suggest that thioproline and methylthioproline are related to the biological activities of traditional Korean fermented foods. (C) 2014 Elsevier B.V. All rights reserved.