Exploring the nephrotoxicity of sulfur-containing derivatives in sulfur-fumigated Panacis Quinquefolii Radix based on chemical profiling and untargeted metabolomics

Panacis Quinquefolii Radix (PQR) is often illegally sulfur fumigated to extend shelf life and improve appearance, but existing regulations of detecting SO2 residues do not accurately identify desulfurized sulfur-fumigated PQR (SF-PQR). Although sulfur-containing derivatives (SCDs) have been reported in some sulfur-fumigated herbs, there is a lack of research on the generation mechanisms and toxicity of SCDs. Our previous study reported the nephrotoxicity of SF-PQR, and there is an urgent necessity to illuminate the mechanism of toxicity as well as its association with SCDs.To investigate the transformation pattern of chemical components and SCDs in SF-PQR, and to disclose the linkage between SCDs and SF-PQR nephrotoxicity.The extracts of PQR (before and after SF) were detected by the UPLC-LTQ-Orbitrap-MS method, and SCDs were screened as quality markers (Q-markers). The composition of sulfur combustion products was examined by ion chromatography to exploit the conversion mechanism of SCDs. After administration of PQR extracts to mice for two weeks, serum was collected for GC-MS-based untargeted metabolomics study to mine for differential metabolites. The upstream genes were traced by network analysis to probe toxicity targets. Molecular docking was used to uncover the interactions between SCDs and the targets.Thirty-three compounds were identified and 11 SCDs of saponins were screened, including four SO3 sulfonation products and five H2SO3 sulfonation products. Metabolomics study showed significant alterations in serum biochemistry of SF-PQR group, with substantial increases in fumarate and 2-heptanone content, and induced disturbances in glycerolipid metabolism and phenylalanine, tyrosine, and tryptophan biosynthesis in mice. Network analysis revealed that the key toxicity targets were DECR1, PLA2G1B, and CAT. Molecular docking indicated that SCDs had stable interaction forces with the above three toxicity targets.SF-PQR caused kidney damage by affecting glycerolipid metabolism and phenylalanine, tyrosine, and tryptophan biosynthesis. Eleven SCDs were potential nephrotoxic substances and Q-markers for identifying SF-PQR. This study is the first to systematically elucidate the mechanism of SF-PQR-related nephrotoxicity, providing a robust basis for the construction of new quality control standards and a global prohibition of sulfur fumigation.