Brazilin exerts protective effects against renal ischemia-reperfusion injury by inhibiting the NF-κB signaling pathway.

Renal ischemia-reperfusion (I/R) injury is associated with high morbidity and mortality as there is currently no available effective therapeutic strategy with which to treat this injury. Thus, the aim of this study was to investigate the potential protective effects of brazilin, a major active component of the Chinese medicine Caesalpinia sappan L., against renal I/R injury in vitro and in vivo. Rats were subjected to removal of the right kidney and I/R injury to the left kidney (ischemia for 45 min followed by reperfusion for 24 h). Treatment with brazilin (30 mg/kg, administered intravenously at 30 min prior to ischemia) led to the reversal of I/R-induced changes in serum creatinine (Scr) and blood urea nitrogen (BUN) levels, and also attenuated the histopathological damage induced by I/R. Furthermore, TUNEL assay revealed that brazilin reduced cell necrosis, and significantly decreased the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1ß in renal tissue. Moreover, HK-2 cells were used in order to elucidate the mechanisms responsible for the protective effects of brazilin. The levels of phosphorylated IκBα and the nuclear translocation of nuclear factor-κB (NF-κB) were all evidently decreased by brazilin. These findings suggested that pre-treatment with brazilin protects against I/R-induced renal damage and suppresses the inflammatory response by inhibiting the activation of the NF-κB signaling pathway.

Application of a liquid chromatography-tandem mass spectrometry method to the pharmacokinetics, tissue distribution and excretion studies of brazilin in rats.

Brazilin is an important constituent of Caesalpinia sappan L., and has several bioactivities. In this study, a rapid and sensitive analytical method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been developed for the determination of brazilin in rat plasma, urine, feces and tissues (brain, heart, liver, lung and kidney and spleen). Biological samples were processed with ethyl acetate containing 5% formic acid extraction, and salicylic acid (SA) was chosen as the internal standard (IS). The separation of brazilin was achieved on an Inspire C18 column (4.6mm×150mm, 5µm) with a mobile phase consisting of methanol/5mM ammonium acetate (80:20, v/v). The MS/MS detection was carried out by monitoring the fragmentation of m/z 285.1→163.0 for brazilin and m/z 137.1→93.1 for SA on a triple quadrupole mass spectrometer. The total run time was only 5.0min. The analyte showed good linearity over a wide concentration range (R(2)>0.995) and its lower limit of quantification was 2ng/mL. The accuracy and precision ranged from 97.1 to 103.3% and 1.7 to 9.1%, respectively. Recoveries (78.9-93.8%) and matrix effects (81.0-97.8%) were satisfactory in all the biological matrices examined. Stability studies (86.4-99.8%) showed that brazilin was stable during the assay procedure and long-term storage. The assay was successfully applied to plasma pharmacokinetics, tissue distribution and excretion study of rats. The pharmacokinetic parameters, such as half-life, mean residence time, maximum concentration were determined. These preclinical data of brazilin would be useful for the clinical reference.