Therapeutic Potential of Impatiens tinctoria Tuber Extract and Its Green Synthesized Silver Nanoparticles against Trichophyton mentagrophytes

Abstract

Dermatophyte infections and antifungal resistance pose a global health challenge, particularly in developing countries, where existing treatments often fail and cause recurrence and side effects. This study evaluated the antioxidant and antifungal properties of Impatiens tinctoria tuber extract and its green-synthesized silver nanoparticles (AgNPs) against Trichophyton mentagrophytes. Tuber extracts were obtained using aqueous, ethanolic, and methanolic solvents, and their phytochemical constituents were analyzed. AgNPs were synthesized using an aqueous extract under optimized conditions (pH 9, 0.1:1 extract-to-AgNO₃ ratio, 5 mM AgNO₃, 45-minute reaction time, and 60°C), with maximum UV-Vis absorbance at 419 nm and an SPR peak at 425 nm confirming formation. AgNPs were characterized via UV–Vis, FTIR, XRD, and SEM, revealing a face-centered cubic crystalline structure with an average crystallite size of 9.28 nm and predominantly spherical morphology. Antioxidant activity was assessed using the DPPH radical scavenging assay, with ethanol extract showing the highest capacity (IC50 = 48.18 ± 1.40 µg/mL), followed by methanol (125.66 ± 1.45 µg/mL) and aqueous (163.70 ± 1.02 µg/mL) extracts. Biosynthesized AgNPs exhibited dose-dependent activity (IC50 = 148.56 ± 0.74 µg/mL), surpassing the aqueous extract but remaining lower than ethanol and methanol extracts. Ethanol extract showed the strongest in vitro antidermatophytic activity against T. mentagrophytes, surpassing terbinafine (inhibition zone: 36.3 ± 1.15 mm at 100 mg/mL). Methanol extract exhibited significant inhibition, while aqueous extract had the lowest effect. AgNPs demonstrated antifungal efficacy, increasing with concentration but remaining less potent than terbinafine. A formulation combining ethanol extract and AgNPs (Formulation 2) significantly enhanced antidermatophytic activity in vitro, while in vivo studies on mice showed faster recovery and complete healing, outperforming individual treatments and proving comparable to terbinafine. Acute oral and dermal toxicity studies confirmed that the ethanol extract, AgNPs, and their formulation were non-toxic at 2000 mg/kg, with no observed toxicity or mortality. These findings suggest that I. tinctoria tuber extract and its green-synthesized AgNPs hold promising potential as alternative therapeutic agents for dermatophytosis treatment