Effect of borneol on the distribution of gastrodin to the brain in mice via oral administration

Both borneol and gastrodin are bioactive substances derived from traditional Chinese medicine. In this paper, the effect of borneol on the distribution of gastrodin to the brain in mice via oral administration was investigated. Gastrodin concentrations in plasma and gastrodigenin (active metabolite of gastrodin) concentrations in the brain of mice were determined by reversed-phase high-performance liquid chromatography, after intragastric administration of gastrodin (200 mg kg(-1)) alone or combined with different doses (200, 400 and 600 mg kg(-1)) of borneol simultaneously or the same dose (400 mg kg(-1)) of borneol given 20 and 40 min beforehand, respectively. Compared with the administration of gastrodin alone, gastrodin coadministrated with borneol could have been rapidly absorbed from the gastrointestinal tract; the peak time of gastrodin in the plasma became shorter (5-15 vs. 30 min); the bioavailability of gastrodigenin in the brain was increased by 33.6-108.8%; and obvious brain-targeting effect was observed. The enhancing effect was attenuated when the dose of borneol was too high (600 mg kg(-1)), or the time interval between the administration of borneol and gastrodin was longer than 40 min. The results indicate that borneol can accelerate the absorption of gastrodin in the gastrointestinal tract and promote its distribution to the brain. Therefore, borneol is a promising promoter for oral brain-targeting drug delivery.