Development of a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for simultaneous determination of epigallocatechin-3-gallate, silibinin, and curcumin in plasma and different tissues after oral dosing of Protandim in rats and its application in pharmacokinetic and tissue distribution studies.

Protandim is an over-the-counter herbal dietary supplement. The key components of Protandim, i.e., epigallocatechin-3-gallate (EGCG), silibinin (SIL), and curcumin (CUR) were simultaneously analyzed through a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method in plasma and different tissues after administration of Protandim in rats. The developed and validated method was employed to assess the pharmacokinetic profiles and the accumulation of EGCG, SIL, CUR in rat plasma and tissue homogenates. The plasma and tissue homogenates were subjected to liquid-liquid extraction and separated on a Hypurity C18 column (50 × 4.6 mm) with a gradient elution of water and acetonitrile. Mass spectrometric detection was performed in the multiple reaction monitoring mode (MRM) following the transitions: m/z 457.3/169.3, m/z 481.3/125.0, m/z 367.3/149.3 and m/z 609.4 /300.2 for EGCG, SIL, CUR, and RU (rutin), respectively. The concentrations of all the analytes in the range from 2 to 1000 ng/mL showed linear relationships with respective peak areas in different matrices. For all matrices, the values of inter-day and intra-day precisions and accuracies were less than 10.3% of the nominal concentration. The matrix effect, extraction recovery, dilution integrity, and stability values were all within acceptable levels. This method was successfully applied for determining the pharmacokinetics and tissue distribution of the components in rats after the intragastrical administration of a single-dose (364.5 mg/kg) or multiple-doses (1458 mg/kg) of Protandim. The data showed that EGCG, SIL, and CUR did not accumulate in rats after multiple doses of Protandim, and the three main components were distributed mainly in the small intestine.