Chemical characterization and pharmacological mechanisms of Qizhi Yishen Capsule in early diabetic kidney disease.

OBJECTIVE: This research explored the bioactive components and therapeutic mechanisms of Qizhi Yishen Capsule (QZC) in managing early-stage diabetic kidney disease (DKD) by integrating network pharmacology with experimental evidence, aiming to support its clinical utility with scientific validation. METHODS: Network pharmacology and molecular docking were utilized to identify QZC's potential targets in DKD treatment. The therapeutic impact of QZC on renal damage in DKD rats was assessed through in vivo tests, including serum biochemistry, histological staining, and transmission electron microscopy analysis.Potential mechanisms were further explored through metabolomics, in vitro experiments, qRT-PCR, and Western blot analysis. RESULTS: The renal protective effects of QZC in DKD were predicted to be mediated via signaling pathways such as PI3K-Akt, AMPK, and MAPK, based on network pharmacology analysis. In vivo studies confirmed that QZC (509 mg·kg-1), in combination with metformin hydrochloride tablets (MET, 104 mg kg-1), significantly alleviated pathological renal injury and improved podocyte ultrastructure in DKD rats. Metabolomics analysis identified 420 candidate biomarkers, of which 157 were upregulated in the DKD model group and downregulated after QZC treatment, and 263 showed the opposite trend. These metabolites were mainly involved in starch and sucrose metabolism, tyrosine metabolism, phenylalanine metabolism, cysteine and methionine metabolism, and the biosynthesis of phenylalanine, tyrosine, and tryptophan. In vitro assays demonstrated that QZC (300 μg ml-1), gamma-linolenic acid (GLA, 12 μmol L-1), and methyl caffeate (MC, 12 μmol L-1)-two active constituents of QZC-significantly inhibited apoptosis in HK-2 cells, regulated the cell cycle, and reduced reactive oxygen species (ROS) levels. qRT-PCR and Western blot analyses indicated that QZC activated AMPK, SIRT1, and PGC-1α expression at the mRNA and protein levels. CONCLUSION: QZC improves hyperglycemia-induced tubular injury and metabolic disorders in DKD rats by suppressing oxidative stress and apoptosis through multi-component and multi-target regulation of the AMPK/SIRT1/PGC-1α signaling pathway. This study integrates network pharmacology, metabolomics, and experimental validation to systematically elucidate, for the first time, the multi-component basis and the AMPK/SIRT1/PGC-1α pathway mechanism underlying QZC's efficacy against early DKD.