Determination of the esculetin contents of medicinal plants by liquid chromatography-tandem mass spectrometry

We developed a LC-MS/MS method for the determination of esculetin contents in medicinal plants. The analysis was performed using multiple reaction monitoring in negative mode, and an XBridge (TM) C18 column (2.1?x?100?mm, 3.5?mu m) was used. Methanol and 0.1% formic acid were used for gradient analysis. The calibration curve showed good linearity (r2?>?0.9993). The limits of detection and quantitation were 0.02 and 0.07?ng/mL, respectively. The intra-day and inter-day precisions were 1.56.8 and 2.05.3%, respectively, and the accuracy was 102.0110.2%. The contents of esculetin in 35 different plants were determined, and Fraxini Cortex showed the highest content of esculetin (7615475?mg/kg). In Mori Folium and Artemisiae Capillaris Herba, 5.221.5 and 7.017.6?mg/kg of esculetin were found, respectively. In other medicinal plants, no esculetin was detected, or it was present at a concentration less than 10?mg/kg. The analysis method appears to be simple, sensitive and reproducible. Contrary to expectations based on traditional medical knowledge, although Artemisiae Capillaris Herba contains a large amount of esculetin, it appears from this study that Fraxini Cortex contains a greater amount. The pharmacological effects of esculetin isolated from medicinal plants should be investigated as part of new medicines development. Copyright (c) 2012 John Wiley & Sons, Ltd.