Green Synthesis of Silver Nanoparticles Using Polyherbal Extracts and Their Incorporation Into a Hydrogel for Anti- Inflammatory Applications

ABSTRACTThe current investigation explores the green synthesis of silver nanoparticles (AgNPs) usingpolyherbal hydroalcoholic extracts of Curcuma longa (rhizomes), Vitex negundo (leaves),and Cardiospermum halicacabum (leaves), with subsequent incorporation into a Carbopol934-based hydrogel for potential topical anti-inflammatory application. The plant materialswere authenticated by the Botanical Survey of India, Coimbatore. Extraction by coldmaceration with 70% ethanol afforded percentage yields of 6.5%, 4.5%, and 4.0% (w/w) forC. longa, V. negundo, and C. halicacabum, respectively. Qualitative phytochemical screeningconfirmed the presence of flavonoids, phenols, tannins, and saponins in all three extracts,with additional carbohydrates in C. longa and alkaloids in C. halicacabumand terpenoids inV.negundo. UV-Visible and FTIR spectroscopic analyses corroborated these phytochemicalfindings. In vitro anti-inflammatory activity, assessed by the egg albumin proteindenaturation inhibition assay, yielded IC50 values of 132, 165, and 217 μg/mL for C. longa,V. negundo, and C. halicacabum, respectively, compared with 79 μg/mL for diclofenacsodium. Silver nanoparticles were synthesised by reacting plant extract with 1 mM AgNO3 atextract: AgNO3 volume ratios of 9:1, 8:2, and 7:3. The 8:2 formulation was selected asoptimal based on a sharp Surface Plasmon Resonance (SPR) peak at 423 nm. FTIR analysisconfirmed that phenolic and flavonoid moieties served as reducing and stabilising agents.Scanning Electron Microscopy (SEM) revealed quasi-spherical nanoparticles predominantlyranging from 61-120 nm, and entrapment efficiency was 74.3%. Six hydrogel formulations(F1-F6) were prepared and evaluated; all exhibited homogeneity, pH 5.09-5.57, spreadability86.90-93.75 g·cm/sec, and viscosity 4456-5190 cP—properties consistent with safe andeffective topical application. These findings demonstrate that the selected medicinal plantspossess significant anti-inflammatory activity and that their phytoconstituents successfullymediate stable AgNP synthesis. The resultant nanoparticle-loaded hydrogel represents a promising candidate as a natural topical anti-inflammatory formulation warranting further in-vivo evaluation.