Pharmacokinetic Profiling and Tissue Distribution of Seven Key Saponins in Rats Following Oral Administration of Panacis Japonici Rhizoma Extracts

The pharmacokinetics and distribution of natural compounds in living organisms are crucial to understanding their therapeutic potential and safety. In the study, ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS) was employed to develop a method for the separation and analysis of seven saponins, namely, G-Rg₁, G-Re, G-Rb₁, G-Ro, PG-RT₁, CS-IV, and CS-IVa, in plasma and tissue samples derived from Panacis Japonici Rhizoma (PJR). Additionally, the pharmacokinetic profiles and tissue distribution characteristics of these saponins in rats were systematically investigated. Following the oral administration of 2 g/kg of PJR extracts, UPLC-MS/MS was utilized to analyze the compounds' presence in plasma and various tissues. Key findings indicate that G-Rb₁ exhibited the highest <i>T</i> _max, <i>T</i> _1/2, <i>C</i> _max, and AUC_0-<i>t</i> values, reflecting its slow and extended presence in the bloodstream. Dual and triple peak phenomena were observed in the plasma concentration-time curves for certain saponins, suggesting complex absorption dynamics. All seven saponins were detected across multiple tissues within 1 h postadministration and remained detectable for up to 10 h, with the lung and brain showing the highest and lowest concentrations, respectively. These results highlight the compounds' broad distribution and prolonged elimination, providing a foundational understanding that is beneficial for future clinical applications of PJR.