Simultaneous determination of catechin, epicatechin and epicatechin gallate in rat plasma by LC–ESI-MS/MS for pharmacokinetic studies after oral administration of Cynomorium songaricum extract

A rapid and valid method was developed for simultaneous determination catechin, epicatechin and epicatechin gallate in rat plasmas using scopoletin (103 ng mL−1) as an internal standard (IS). The separation was performed on Eclipse plus C18 column (100 mm × 4.6 mm, 1.8 μm) at a flow rate of 0.3 mL min−1, and acetonitrile–0.1% formic acid was used as mobile phase. The recoveries of three analytes and IS were more than 78.9%. The lower limits of quantitation (LLOQ) in rat plasma were 2.14, 2.38 and 2.08 ng mL−1 respectively for catechin, epicatechin and epicatechin gallate. Intra-day and inter-day precisions were within 12%. The accuracies were more than 85%. After single oral administration of 15.25 g kg−1 Cynomorium songaricum extract, Cmax of catechin, epicatechin and epicatechin gallate in rat plasma were respectively 86.69 ± 38.65, 32.57 ± 15.00 and 36.93 ± 12.62 ng mL−1 while Tmax values were respectively 0.15 ± 0.09, 0.20 ± 0.10 and 0.20 ± 0.13 h. The results demonstrated that the present LC–MS/MS method was sensitive enough for pharmacokinetic study of catichins following oral administration of C. songaricum extract.