Effects of Drynaria quercifolia (L.) J. Sm. rhizome extract silver nanoparticles in Freund’s Complete Adjuvant (FCA)-induced rheumatoid arthritis in rats

Rheumatoid Arthritis (RA) is a chronic inflammatory autoimmune disease, causing joint destruction, persistent synovitis, and systemic complications, including increased cardiovascular and pulmonary risk. A mixture of disease-modifying anti-rheumatic drugs (DMARDs) and non-steroidal anti-inflammatory drugs (NSAIDs) is prescribed. However, these medications have side effects, requiring substitute treatments. Silver nanoparticles (AgNPs) have been used to deliver anti-inflammatory drugs, but conventional synthesis methods can be harmful. Drynaria quercifolia (L.) J. Sm., known in Traditional Chinese Medicine (TCM) as Gǔ Suì Bǔ (骨碎补), is an herb used to strengthen bones, promote fracture healing, and alleviate musculoskeletal disorders associated with inflammatory joint diseases. Use of this ethnomedicinal fern, D. quercifolia, as a stabilizing and reducing agent during AgNPs synthesis might enhance therapeutic effectiveness. Silver nanoparticles (DQ-AgNPs) were synthesized using aqueous rhizome extract (DQAQ) as a reducing and stabilizing agent and characterized by UV-Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and energy-dispersive X-ray analyses (EDX). In vitro antioxidant (DPPH assay), anti-inflammatory (protein denaturation assay), and antibacterial activities (agar well diffusion, MIC/MBC) were evaluated. In vivo anti-arthritic activity was assessed in Freund’s Complete Adjuvants (FCA)-induced rheumatoid arthritis in Wistar albino rats through biometric, hematological, biochemical, radiological, and histological analyses. DQ-AgNPs showed significant anti-oxidant activity (IC50: 10.7 µg/ml), and both DQ-AgNPs and DQAQ demonstrated anti-inflammatory activity (IC50: 51.50 µg/ml and IC50: 50.82 µg/ml, respectively). In FCA-induced arthritis rats, DQ-AgNPs and DQAQ significantly reduced paw edema and arthritis scores ( p ≤0.001), improved hematological and biochemical parameters, and prevented joint space narrowing and inflammatory cell infiltration. Radiological and histological findings further confirmed the protective effects. Therefore, it can be concluded that DQAQ and DQ-AgNPs have strong bactericidal, anti-inflammatory, and anti-arthritic properties.