Determination of protopine in rat brain after oral administration of the extract of Corydalis decumbentis

A simple and sensitive high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed to determine protopine in rat brain samples after oral administration of the extract of Corydalis decumbentis. The extract of C. decumbentis was administered at a dose of 6.88 g/kg (equivalent to 159.62 mg/kg of protopine). The lower limit of quantification was 18.9 μg/ml for protopine. The calibration curve was linear over a concentration range of 21.6 to 324 μg/ml. Brain tissues samples were obtained at regular time intervals after oral administration of C. decumbentis extract. Protopine could be detected rapidly in rat brain after 30 min of oral administration and reach maximum concentration at about 10 h in male rat and 6 h in female rat. Furthermore, there was a great difference between male and female rats. In female rats, the maximum concentration was about twice that of male rats. This results obtained illustrate the pharmacokinetic behavior of protopine in brain tissue, and maybe helpful to explain the C. decumbentis bioactivity in cerebrovascular disease.