Liquid chromatographic method with amperometric detection to determine acteoside in rat blood and brain microdialysates and its application to pharmacokinetic study.

A simple and sensitive liquid chromatography with amperometric detection was developed for the first time to monitor the protein-unbound acteoside in the rat blood and brain microdialysate by microdialysis technique. Microdialysis samples without further cleanup procedures were directly injected into the HPLC and separated using a reversed-phase C18 column (150 mmx2 mm, i.d. 5 microm) maintained at ambient temperature and a mobile phase comprised of acetonitrile-50 mM monosodium phosphate (pH 2.8) (17:83, v/v) with a flow rate of 0.2 mL/min. Based on the experimental voltamogram, the applied potential was set at +0.9 V oxidative mode. The concentration-response relationship was linear (r2>0.99) over a concentration range of 5-500 ng/mL; method precision and accuracy fell within predefined limits (less than 20%). The developed method was applied to assess the pharmacokinetics of acteoside, and the results suggested that acteoside was fitted better by the two-compartmental model following a single intravenous injection of acteoside. Acteoside was unable to be detected in the brain dialysate. The distribution and elimination half-lives of unbound acteoside in the blood were 5 and 28 min, respectively, which suggested the rapid distribution of acteoside.