Core constituents and pharmacodynamically equivalent ratios of Polygonum capitatum against urinary tract infection: involvement of Nrf2/HO-1 and NF-κB pathways

This study established HPLC fingerprints of PCAE 70% and RLQ, supported by the 2020 edition of the Chinese Pharmacopeia and relevant literature, and performed network pharmacology prediction for the common constituents. • Multi-index regression analysis of uniform design data was conducted by partial least squares, by which seven active components were optimized and determined as six important active components, and their rationality was experimentally validated. • The entropy weight method was employed to unify heterogeneous data from in vitro and in vivo experiments, and the integrated important active component combination was subjected to in vivo activity validation through a mouse urinary tract infection model. • This study suggests that the active components centered on gallic acid, myricitrin, and quercitrin may constitute the major pharmacodynamic material basis of Polygonum capitatum against UTI, and preliminarily explored the underlying mechanism. Ethnopharmacological relevance As a cornerstone herb in the traditional medicine of the Miao ethnic group in Guizhou Province, Polygonum capitatum has long been used to treat diseases of the urinary system. Documented in Miao medical theory as cold in nature and bitter-pungent in taste, and as acting on the kidney and bladder meridians, it is traditionally used to clear heat, promote diuresis, relieve stranguria, and detoxify, thereby relieving pain. The aqueous extract of this herb is the sole component of Relinqing Granules (RLQ), a clinically widespread formulation. Despite its broad clinical application, the underlying material basis of its pharmacological activity remains to be fully elucidated. Materials and methods The target compounds were identified through literature investigation, and their presence in both the Polygonum capitatum 70% aqueous ethanol extract (PCAE 70%) and RLQ was subsequently verified. The common constituents shared by the two were identified by comparing the fingerprint chromatograms with reference standards, and network pharmacology was employed to predict the potential targets of these components. The constituents were then combined through uniform design to evaluate their antibacterial, anti-inflammatory, and antioxidant activities, optimized via partial least squares regression and the entropy weight method, and ultimately validated in a mouse model of UTI. Results A total of seven common constituents were identified: gallic acid, protocatechuic acid, catechin, myricitrin, quercitrin, quercetin, and kaempferol. Network pharmacology predicted that these constituents might exert anti-UTI effects through modulation of the PI3K-Akt signaling pathway. The optimal ratio combination demonstrated significant antibacterial activity against Escherichia coli and Staphylococcus aureus , while another optimal ratio enhanced catalase activity and modulated the expression of AKT-1/Nrf 2 / HO-1/NF-κB 3 in zebrafish. Following data integration using the entropy weight method, mouse validation results revealed decreased TNF-α/IL-1β levels and increased IL-10 levels, with superior efficacy compared to PCAE 70% and RLQ, without dose-dependent differences. The results implied that gallic acid, myricitrin, and quercitrin represent the potential principal active components of P. capitatum. Conclusion The optimized combination dominated by gallic acid, myricitrin, and quercitrin, identified from P. capitatum , exhibited antibacterial, anti-inflammatory, and antioxidant performance superior or equivalent to existing preparations, holding significant theoretical and practical value. Download: Download high-res image (228KB) Download: Download full-size image Graph A illustrates the experimental procedure for determining the in vitro antibacterial activity of target drugs by the MTT method; Graph B illustrates the experimental procedure for the acute toxicity assay in zebrafish; Graph C illustrates the mechanism diagram of drug administration in the zebrafish oxidative stress model; Graph D illustrates the simplified experimental procedure and mechanism diagram before drug administration in the mouse UTI model.