Mechanism exploration of ancient pharmaceutic processing (Paozhi) improving the gastroprotective efficacy of Aucklandiae Radix

Processing, also called Paozhi in Chinese, is an ancient Chinese pharmaceutic processing technique developed along with the Chinese herbal medicines (CHMs). The understanding of the mechanism of Paozhi has been investigated for several decades. Aucklandiae Radix (CAR) and its roasted processed products are all used in indigestion as a kind of CHMs. Processed Aucklandiae Radix (PAR) had a stronger effect to protect gastric mucosa than CAR, while the main compounds in CAR were reduced sharply after being processed. The underlying mechanism of this phenomenon is still unclear.This study was aimed to evaluate whether PAR have a stronger gastroprotective effect than CAR and the underlying mechanisms of such circumstance.Ultra-fast liquid chromatography coupled with quadrupole time of flight mass spectrometry (UFLC-QTOF-MS/MS) coupled with multivariate statistical analyses was employed to explore chemical compounds which had a relatively stable content in PAR. Based on the compounds selected as the research object, network pharmacology was applied to visualize the relationships between the selected components and the gastroprotective-related targets from disease database, at the same time the possible intervention path of CAR/PAR which might be responsible for the effect of CAR/PAR on gastritis-induced rats was also built. Then, the key proteins were detected by western blotting to verify and compare the pharmacological effects of CAR/PAR.Through UFLC-QTOF-MS/MS and orthogonal partial least squares discriminant analysis (OPLS-DA), sixteen compounds stable in PAR were discovered, of which saussureamine C and saussureamine B were estimated as the core compounds to exert gastroprotective in PAR predicted by network pharmacology analysis. Under the guide of KEGG pathway enrichment analysis, PI3K/AKT, p38 MAPK (Mitogen-activated protein kinase) and nuclear factor-kappa B (NF-κB) signaling pathways were forecasted as the possible healing mechanisms of CAR/PAR, and that result was verified by the experiments in vivo. PAR performed a stronger ability to reduce the level of p38 MAPK and NF-κB p65 than CAR, which may partially explain the different ability of CAR/PAR against gastric mucosa damage.This study clarified that although Paozhi entailed a sharp decrease on the main compounds of CAR, there were some compounds which were not sensitive to high temperature and preserved in PAR and had a relative higher content in PAR than in CAR. PAR has stronger influence on MAPKs/NF-κB signaling pathway than CAR, which may reveal that the stronger gastroprotective effect of PAR perhaps rely on the constitutions with a higher relative abundance after Paozhi. The present research combined UFLC-QTOF-MS/MS and network pharmacology deeply investigated the impact of the roasted processing on the chemical constitutions and gastroprotective effect of CAR and offered reference for the clinical application of CAR/PAR.