Comparative Physicochemical Characterisation, Antimicrobial, Anti-Inflammatory, and Analgesic Profiling of Silver Nanoparticles Biosynthesised from Sambucus wightiana Extract

Abstract

Background: Plant mediated green synthesized silver nanoparticles (AgNPs) are versatile nanomaterials as they possess inherent antimicrobial property with phytochemical bioactivity. Sambucus wightiana Wall. ex Wight & Arn. (Adoxaceae) is an ethnomedicinally important Himalayan shrub rich in flavonoids, tannins, and phenolic acids. Its potential as an AgNP precursor has not previously been reported in the literature.

Objective: To synthesize, fully characterize, and evaluate the antimicrobial, anti-inflammatory, and analgesic activities of AgNPs biosynthesized from the aqueous leaf extract of S. wightiana, and to contextualize the findings within the global literature on plant-mediated AgNPs.

Methods:

Silver nanoparticles (AgNPs) were biosynthesized by reacting 1 mM AgNO₃ with 10% (w/v) aqueous Sambucus wightiana extract under continuous stirring (350 rpm) at 37°C for 24 hours. The resulting AgNPs were characterized using UV–Vis, XRD, FTIR, SEM, TEM, EDS, DLS, and zeta potential analyses. Their antimicrobial activity was tested against nine bacterial and nine fungal strains using agar well diffusion and agar slant dilution methods, respectively, with the minimum inhibitory concentration (MIC) determined via broth microdilution. The anti-inflammatory and analgesic effects were evaluated in BALB/c mice using carrageenan-induced paw edema and hot plate tests after intraperitoneal injection of AgNPs at doses of 5, 10, and 20 mg/kg. Results showed a color change to yellow-brown indicating AgNP formation, with UV-Vis revealing a peak at 423 nm. XRD confirmed a face-centered cubic (FCC) crystalline structure (JCPDS 04-0783), with the strongest (111) reflection at 38.2°. FTIR identified surface-capping phytochemicals with hydroxyl, C=C, C–N, and C=N groups. TEM showed mostly spherical, hexagonal, or rod-shaped particles, 12–30 nm in diameter. The Zeta potential of −24.5 mV indicated good colloidal stability. The AgNPs demonstrated strong antibacterial activity, notably against Escherichia coli (ZOI 28 mm; MIC 0.05 mg/mL) and Pseudomonas aeruginosa (ZOI 29 mm; MIC 0.02 mg/mL), along with antifungal activity against Fusarium solani (80% inhibition at 100 µg) and Aspergillus terreus (90% inhibition at 140 µg). At 20 mg/kg, AgNPs achieved 57.05% inhibition of carrageenan-induced paw edema after 5 hours (P<0.001) and 42.19% analgesic protection at 90 minutes (P<0.001)..

Conclusion: S. wightiana-mediated AgNPs exhibit broad-spectrum antimicrobial activity, anti-inflammatory effects, and analgesic properties, highlighting their potential as green-synthesized nanomaterials for pharmacological applications. Their antimicrobial potency exceeds that of AuNPs from the same source, attributed to silver ion-mediated disruption of bacterial membranes, enhanced by phytochemical synergy.