Brain Distribution Study of Imperatorin in Rats after Oral Administration Assessed by HPLC

Imperatorin (IMP) is a biologically active ingredient isolated from a traditional Chinese medicine (TCM), Angelica dahurica. To obtain the brain distribution data of IMP in rats, the concentrations of IMP in cortex, cerebellum, diencephalon, brain stem, striatum and hippocampus were measured by a simple and sensitive HPLC-UV method. The analytes were prepared by a liquid-liquid extraction method and the separation of IMP was performed on a Hypersil BDS C 18 column (250 mm x 4.6 mm i.d., 5 μm) using acetonitrile-water (60:40, v/v) as mobile phase which was delivered at 1.0 mL min-1. Ultraviolet detection was performed at 300 nm. Using a weighted (1/c2) least square method, linear calibration curves for the six regions were obtained (r ≥ 0.9990) with a lower limit of quantification (LLOQ) of 0.075 μg g-1 for cortex, cerebellum, diencephalon and brain stem or 0.15 μg g-1 for striatum and hippocampus, and the recovery was greater than 90% for each tissue sample. The within- and between-day precisions (expressed as the relative standard deviation, RSD) were less than 10%. The validated method has been successfully applied to the brain distribution study in rats. The results showed that IMP could pass through the blood-brain barrier easily. And the higher concentration in striatum and hippocampus compared with the others might indicate that they were the target regions of IMP in rat brain.