Biogenic Silver Nanoparticle-Loaded Nanohydrogel of Oroxylum indicum Root Extract Alleviates Psoriasiform Skin Inflammation in Rats: Evidence from PASI and Cytokine Regulation

Abstract Aim The present study aimed to develop and optimize a green-synthesized silver nanoparticle (AgNP)-loaded nanohydrogel containing O. indicum root extract for topical antipsoriatic therapy. Methods The ethanolic root extract was subjected to phytochemical evaluation and used for green synthesis of AgNPs. A central composite design was employed to optimize AgNPs using AgNO₃ concentration and stirring speed, with particle size and entrapment efficiency as responses. The optimized nanoparticles were incorporated into a Carbopol 940-based nanohydrogel and optimized using Carbopol 940 and PEG 400, with viscosity and zeta potential as responses. The optimized formulation was further characterized and evaluated for in vitro antioxidant, anti-inflammatory, antimicrobial, dermal safety, and antipsoriatic activity. Results The optimized AgNPs exhibited a particle size of 170.5 nm and 80.48% entrapment efficiency . The optimized nanohydrogel showed a predicted viscosity of approximately 6742 cP and zeta potential of − 28.82 mV . The formulation demonstrated 84.74% cumulative drug release within 3 h . In vitro assays confirmed concentration-dependent antioxidant and anti-inflammatory activities. In the DNFB-induced psoriasis model, the 400 mg/kg formulation produced marked improvement, reducing ear thickness to 0.246 ± 0.013 mm , PASI score to 1.9 ± 0.5 , IL-6 to 33.45 ± 3.49 pg/mL , TNF-α to 44.61 ± 4.61 pg/mL , and IL-1β to 30.25 ± 3.73 pg/mL . The formulation also showed good dermal tolerability, with only mild transient erythema observed during the irritation study. Conclusion The findings demonstrate that O. indicum root extract-loaded green-synthesized AgNP nanohydrogel possesses promising antioxidant, anti-inflammatory, and antipsoriatic activity , with the 400 mg/kg formulation showing the greatest therapeutic response. The developed nanohydrogel therefore represents a promising topical approach for further investigation in psoriasis management.