Abstract

GREEN SYNTHESIS AND CHARACTERIZATION OF SILVER NANOPARTICLES USING LEAF EXTRACT FROM CITRUS LIMON (L.) OSBECK AND ITS ANTIBACTERIAL, ANTIOXIDANT AND ANTI-INFLAMMATORY ACTIVITIES

Sunitha V. Hegde, Girisha S. T., Dilip Kumar R., Rajeshwari H. Patil, Hemanth K. C., Narasimhamurthy K.*

ABSTRACT

The present research comprise of green synthesis of silver nanoparticles (AgNPs) by Citrus limon leaf extracts and to assess the antimicrobial, antioxidant and anti-inflammatory activity. The synthesized AgNPs were characterized using UV–Vis spectroscopy, FTIR, SEM and XRD, which collectively confirmed the successful formation of stable and crystalline nanoparticles with defined particle sizes. UV–Vis analysis showed a surface plasmon resonance (SPR) peak centered at 405 nm, indicating the presence of AgNPs. The FTIR spectrum revealed distinct absorption bands at 2072.96 cm-1, 642.45 cm-1, and 620.55 cm-1, suggesting the involvement of functional groups in stabilization. SEM analysis demonstrated that the nanoparticles had an irregular morphology, with a broad size distribution and noticeable aggregation. Particle size measurements in selected areas ranged from 79.4 to 222 nm. Furthermore, XRD analysis exhibited five prominent diffraction peaks at 38.00°, 44.04°, 45.63°, 64.29°, and 77.28°, which correspond to the (111), (200), (210), (220), and (311) planes of face-centered cubic silver, confirming their crystalline structure. Bioactivity assays revealed that - AgNPs from Citrus limon exhibited significant antimicrobial, antioxidant, and anti-inflammatory activities. Zone of inhibition increases with concentrations 25- 200µg/ml. The highest zone of inhibition 16 mm for B. subtilis and 15 mm for E. mori was observed at 200µg/ml. The minimum inhibitory concentration (MIC) assay of C. limon-AgNPs demonstrated a dose-dependent antimicrobial effect, the lowest concentration of 5 µg/ml was inhibition of 9.09%. The antioxidant activity of C. limon-derived AgNPs was evaluated using the DPPH radical scavenging assay, and concentration-dependent increase in radical scavenging activity, with inhibition ranging from 9.2% at 25 µg/ml to 32.3% at 200 µg/ml. The anti-inflammatory activity of C. limon derived AgNPs increased in a concentration dependent manner with inhibition ranging from 8.45% at 25 µg/ml to 20.41% at 200 µg/ml. Based on our studies, further identification of the major compounds of leaf extracts is acceptable.

Keywords: Citrus limon, silver nanoparticles, antibacterial, antioxidant minimum inhibitory concentration, anti-inflammatory.