A comparative metabolomics study on dried and processed Rehmannia Radix

The efficacy of Rehmannia Radix changes after processing. However, the precise effect of processing on the property of Rehmannia Radix is an intricate topic, as this effect cannot be explained by traditional methods. The purpose of this study was to investigate how processing methods influence the property of Rehmannia Radix, as well as the changes in body function after administering dried Rehmannia Radix (RR) and processed Rehmannia Radix (PR) using a metabolomics approach. In addition, principal component analysis and orthogonal partial least squares discriminant analysis models were generated using SIMCA-P 14.0, to evaluate the property of RR and PR. Potential biomarkers were identified, and associated metabolic networks were established to clarify differences in the property and efficacies of RR and PR. The results showed that RR and PR have cold and hot property, respectively. RR can exert a hypolipidaemic effect by regulating nicotinate and nicotinamide metabolism. PR exerts a tonic effect and regulates the body’s reproductive function through the regulation of alanine, aspartate, and glutamate metabolism, arachidonic acid, pentose, and glucuronate metabolism, respectively. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based metabolomics is a promising approach to determine the cold/hot property of traditional Chinese medicine formulations.