Icariin Attenuates Diabetic Cardiomyopathy by Activating Nrf2-Dependent Antioxidant and Mitochondrial Pathways: Integrative Evidence from Network Pharmacology and Experimental Validation.

Abstract

Ethnopharmacological relevance: Icariin (ICA), a flavonoid glycoside from Epimedium brevicornu Maxim, has been used in traditional Chinese medicine for cardiovascular and metabolic disorders. While its effects on tonifying kidney yang and treating age-related conditions are well-documented, the underlying mechanisms, particularly in diabetic cardiomyopathy (DCM), are not fully understood, especially regarding oxidative stress and mitochondrial function.

Aim of the study: This study sought to examine the cardioprotective effects of ICA on DCM and to clarify whether these effects are mediated through the Nrf2-dependent antioxidant and mitochondrial pathways.

Materials and methods: We employed an integrative strategy combining network pharmacology, molecular docking (MD), and experimental validation. ICA-Nrf2 binding was assessed by MD and 100 ns. In vivo, diabetic mice induced by STZ and high-fat diet were treated with varying doses of ICA treatment, with or without the Nrf2 inhibitor ML385. Cardiac function, histopathology, mitochondrial morphology, and oxidative markers were evaluated. In vitro, HL-1 and primary mouse cardiomyocytes were exposed to high glucose (HG) and treated with ICA and/or Nrf2 overexpression. Antioxidant signaling, Western blotting, qRT-PCR, immunofluorescence, and biochemical assays were employed to evaluate mitochondrial function and ROS levels.

Results: ICA dose-dependently improved cardiac function and alleviated myocardial hypertrophy and fibrosis in DCM mice. It increased Nrf2 expression levels, upregulated HO-1, SOD2, PGC1-α, and TOM20, enhanced antioxidant enzyme activity, and suppressed ROS and MDA accumulation. In vitro, ICA reduced oxidative stress, preserved mitochondrial integrity, and decreased cardiomyocyte apoptosis. Network pharmacology and in silico modeling identified Nrf2 as a core ICA target, with stable ICA-Nrf2 binding confirmed by dynamics simulation. Notably, Nrf2 inhibition by ML385 partially reversed ICA's cardioprotective and mitochondrial effects, confirming the Nrf2-dependence of ICA's action.

Conclusions: ICA confers potent cardioprotection against DCM by directly activating Nrf2 signaling, enhancing mitochondrial antioxidant defense, and attenuating oxidative stress-induced myocardial injury. These findings highlight ICA as a promising natural Nrf2 activator for oxidative stress-related diabetic heart disease.