Objective To explore the differences in the in vivo drug metabolism of raw and processed Dahuang (Rhei Radix et Rhizoma) in a rat model of middle cerebral artery occlusion and reperfusion (MCAO/R). Methods The MCAO/R rat model was established by the suture method. The successfully modeled rats were randomly divided into model group, raw Rhei Radix et Rhizoma (2.50 g/kg) group and processed Rhei Radix et Rhizoma group, with six rats in each group. Rats were administered continuously for 7 d. 12 h before the last administration, the rats were fasted, and 1 h after administration, blood and brain tissues were collected. Ultra-high performance liquid chromatography-quadrupole electrostatic field orbitrap linear ion trap mass spectrometry (UPLC-Orbitrap Fusion Lumos Tribrid-MS) was used to characterize the prototypes and metabolites of raw and processed Rhei Radix et Rhizoma in plasma and brain tissues of MCAO/R rats. Multivariate statistical analysis was used to screen the differential components, and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) technique was combined to visualize the in situ spatial distribution of the differential components of raw and processed Rhei Radix et Rhizoma in brain tissue. Results A total of 109 prototype components and metabolites were identified in MCAO/R rats. According to variable important in projection (VIP) > 1 and P < 0.05, 23 and eight differential components of raw and processed Rhei Radix et Rhizoma were screened from the plasma and brain tissues, respectively. In the plasma of processed Rhei Radix et Rhizoma group, anthraquinone glycosides were decreased, while in the brain tissue, aglycones and metabolites (such as gallic acid, M31) were increased, and were mainly distributed in hippocampus, midbrain and cortex of brain tissue. The common differential components gallic acid and metabolite M31 were significantly increased in the processed Rhei Radix et Rhizoma group and were specifically enriched in the striatum. Conclusion This study characterized and spatially located the differential components of raw and processed Rhei Radix et Rhizoma in MCAO/R rats and found that processed Rhei Radix et Rhizoma increased the exposure levels of active aglycones and metabolites in the brain, enhancing its protective effect on brain tissue, providing a scientific basis for the “different treatment for raw and processed” processing theory.

UPLC-MS/MS  /  desorption electrospray ionization mass spectrometry imaging  /  raw and processed Rhei Radix et Rhizoma  /  rats with middle cerebral artery occlusion and reperfusion  /  multivariate statistical analysis  /  anthraquinone components  /  chrysophanic acid  /  physcion  /  rhein  /  gallic acid