Diosgenin-Loaded Silver Nanoparticles Mitigate B[a]P-Induced Lung Fibrosis Through Modulation of Oxidative Stress and Inflammatory Pathways.

Background: Lung fibrosis, characterized by the thickening and scarring of lung tissue, is a serious condition often triggered by environmental toxins like Benzo[a]pyrene (B[a]P). Diosgenin, a natural steroidal sapogenin found in plants such as fenugreek and wild yam, has shown potential to protect against lung damage due to its anti-inflammatory and antioxidant properties. However, its clinical application is limited by poor solubility and bioavailability.

Objective: The current investigation aims at developing diosgenin-loaded silver nanoparticles (DioAgNPs) to enhance their delivery and efficacy. This study investigates the preparation, characterization, and protective effects of Dio-AgNPs against B[a]P-induced lung fibrosis in mice.

Methods: Acute toxicity studies in mice were conducted to determine the lethal dose (LD50) of DioAgNPs. Sub-lethal doses (1/50 and 1/20 LD50) were selected for subsequent experiments. Mice were exposed to B[a]P to induce lung fibrosis. Dio-AgNPs were administered to assess their protective effects. Biochemical assays measured levels of total cholesterol (TC), triglycerides (TG), malondialdehyde (MDA), nuclear factor kappa B (NF-κB), interleukin-6 (IL-6), matrix metalloproteinase-2 (MMP2), and matrix metalloproteinase-12 (MMP12). Additionally, high-density lipoprotein cholesterol (HDL-C), glutathione (GSH), catalase (CAT), and glutathione peroxidase (GPx) levels were evaluated. Quantitative PCR (qPCR) was used to analyze the expression levels of lung signal transducer and activator of transcription 3 (STAT3), transforming growth factor- β1(TGF-β1), and Sirtuin 1 genes. Insilico molecular docking studies were performed to evaluate the binding affinity of diosgenin with SIRT1, STAT3, and TGF-β1 proteins, with binding energies (ΔG) calculated to predict interaction strength.

Results: The synthesized Dio-AgNPs exhibited a mean diameter of 51.60±1.54 nm, a zeta potential of -19.5 mV, and encapsulation efficiency of 84.98%, confirming their stability through spectral analysis. In B[a]P-exposed mice, there was a significant elevation in TC, TG, MDA, NF-κB, IL-6, MMP2, and MMP12 levels, alongside a reduction in HDL-C, GSH, CAT, and glutathione peroxidase (GPx) levels. Additionally, lung STAT3 and TGF-β1 gene expression was upregulated, while SIRT1 gene expression was downregulated. Administration of Dio-AgNPs to B[a]P-treated mice resulted in a significant reduction in TC, TG, and HDL-C levels, improvement in lung MDA, NF-κB, IL-6, MMP2, and MMP12 levels, downregulation of lung STAT3 and TGF-β1, and upregulation of SIRT1 gene expression. In-silico molecular docking studies demonstrated strong binding affinities of diosgenin with SIRT1, STAT3, and TGF-β1 proteins, with binding energies (ΔG) of -9.7, -9.6, - 10.1, and -9.7 kcal/mol, respectively.

Conclusion: This study innovatively enhances the delivery and efficacy of diosgenin by developing diosgenin-loaded silver nanoparticles (Dio-AgNPs), addressing its solubility and bioavailability challenges. Dio-AgNPs demonstrated significant protective effects against B[a]P-induced lung fibrosis in mice, reducing oxidative stress and inflammation while modulating key genes like STAT3, TGF-β1, and SIRT1. Molecular docking studies confirmed strong binding affinities, underscoring the therapeutic potential of Dio-AgNPs. This research marks a significant advancement in nanomedicine and respiratory therapy, offering a promising approach to managing lung fibrosis and related conditions.