Mechanisms of radix rehmanniae praeparata in treating blood deficiency: A study on chemistry, metabolomics, and gut microbiota

To investigate the mechanism of Radix Rehmanniae Praeparata (RRP) in treating blood deficiency syndrome (BDS) by analyzing the changes in chemical components before and after processing, and its effects on metabolomics and gut microbiota in BDS mice. Ultra-high-performance liquid chromatographyquadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was employed to screen differential components before and after the processing of Radix Rehmanniae (RR). Pharmacodynamic studies were conducted to validate the therapeutic effects. Additionally, UPLC-Q-TOF-MS, headspace sampling-gas chromatography-mass spectrometry (HS-GC-MS), and 16sRNA sequencing were used to investigate the regulatory effects of RRP on metabolomics and the gut microbiota in BDS mice. The primary differential components identified were iridoids, phenylethanoid glycosides, sugars, benzaldehydes, and 5-hydroxymethylfurfural and its derivatives. RRP effectively ameliorated blood and energy metabolism in BDS mice. It regulates the biosynthesis pathway of unsaturated fatty acids, increases the abundance of Firmicutes to elevate butyric acid levels, and reduces the abundance of Bacteroidetes to downregulate acetic and propionic acid levels, thereby exerting therapeutic effects on BDS. RRP attenuated the metabolic state of BDS mice by modulating metabolic pathways and gut microbiota balance, providing a scientific basis for its clinical application.