Effects of borneol on the pharmacokinetics of geniposide in cortex, hippocampus, hypothalamus and striatum of conscious rat by simultaneous brain microdialysis coupled with UPLC–MS

It has been verified that borneol could promote the accumulation of other drugs in the whole brain. In this study, a microdialysis sampling system coupled with UPLC–MS was developed to evaluate the delivery of geniposide to four brain regions (cortex, hippocampus, hypothalamus and striatum) of conscious rats in the absence/presence of borneol: rats were administrated with geniposide alone (300 mg/kg, iv) or administrated with both geniposide and borneol (0.2 g/kg, ig). The dialysate collected from specific brain area was analyzed by a UPLC–MS system: separated on a BEH C18 column (50 mm × 2.1 mm id, 1.7 μm) within 1.5 min, and detected in positive ion electrospray mode. The calibration curve was in good linearity over the concentration range of 0.009–90 μg/mL. The inter- and intra-day accuracies were within ±10%, and the precisions were within 9.13%. The established method was applied to study the brain pharmacokinetics of geniposide and the results demonstrated that borneol markedly facilitated the delivery of geniposide to hippocampus and hypothalamus, but slightly hampered its delivery in cortex.

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► We monitored the concentration of geniposide from four brain regions of conscious rat.
► A microdialysis combining with an efficient UPLC–MS method was adopted.
► The delivery of geniposide in cortex was more than that in other regions in physiological status.
► Borneol increased the delivery of geniposide in hippocampus and hypothalamus.
► Borneol affect the opening of BBB in a region specific manner.