Scutellariae radix and coptidis rhizoma ameliorate glycolipid metabolism of type 2 diabetic rats by modulating gut microbiota and its metabolites

Scutellariae radix (Scutellaria baicalensis Georgi, SR) and coptidis rhizoma (Coptis chinensis Franch, CR) are both widely used traditional Chinese medicines and have been used together to treat T2DM with synergistic effects in the clinical practices for thousands of years, but their combination mechanism is not clear. Accumulating evidences have implicated gut microbiota as important targets for the therapy of T2DM. Thus, this study aimed to unravel the cooperation mechanism of SR and CR on the amelioration of T2DM based on the systematic analysis of metagenome and metabolome of gut microbiota. Bacterial communities were analyzed based on high-throughput 16S rRNA gene sequencing. Furthermore, ultra high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) was used to analyze variations of microbial metabolites in feces and the contents of short chain fatty acids (SCFAs) in the cecum were determined by a gaschromatography-flame ionization detector (GC-FID). 16S rRNA gene sequencing results revealed that T2DM rats treated with SR, CR, and the combination of SR and CR (SC) exhibited changes in the composition of the gut microbiota. The SCFAs-producing bacteria such as Bacteroidales S24-7 group_norank, [Eubacterium] nodatum group, Parasutterella, Prevotellaceae UCG-001, Ruminiclostridium, and Ruminiclostridium 9 in T2DM rats were notably enriched after treatment with SR, CR, and their combination. In contrast, secondary bile acid-producing bacteria such as Escherichia-Shigella strongly decreased in numbers. The perturbance of metabolic profiling in T2DM rats was obviously improved after treatment, exhibiting a lower level of secondary bile acids and a numerical increase of microbially derived SCFAs. Moreover, the correlation analysis illustrated a close relationship among gut microbiota, its metabolites, and T2DM-related indexes. The findings indicated that the crosstalk between microbiota-derived metabolites and the host played an important role in the progress of T2DM and might provide a novel insight regarding gut microbiota and its metabolites as potential new targets of traditional Chinese medicines. Furthermore, this work also suggested that the integration of various omics methods and bioinformatics made a useful template for drug mechanism research.