GREEN SYNTHESIS OF SILVER NANOPARTICLES FROM DEBREGEASIA LONGIFOLIA (BURM. F.) WEDD. LEAF EXTRACT AND THEIR ANTIOXIDANT, ANTIBACTERIAL AND ANTIDIABETIC APPLICATIONS

Abstract

This study focused on synthesising silver nanoparticles (AgNPs) using aqueous leaf extract of Debregeasia longifolia and compared their properties with methanolic extract (Met-Ext-D.L) for antioxidants, antibacterial, and antidiabetic potential. Gas chromatography-mass spectrometry (GC-MS) identified 50 bioactive compounds in Met-Ext-D.L. The formation of AgNPs was confirmed by UV-visible spectroscopy, showing an SPR peak in 300-400 nm range. Fourier-transform infrared spectroscopy (FTIR) showed 4 peaks (3276.33, 2094.76, 1632.57, and 421.19 cm⁻¹), indicating the presence of functional groups. X-ray diffraction (XRD) confirmed the cubic crystalline structure of AgNPs, and energy-dispersive X-ray spectroscopy (EDX) identified silver as a major element (48.77%). Scanning electron microscopy (SEM) showed spherical AgNPs, ranging from 10-100 nm in size. Both Met-Ext-D.L and AgNPs-D.L showed significant free radicals scavenging activity, with AgNPs showing the highest activity (88% at 1000 µg/mL, IC50 = 80 µg/mL). They also showed good antibacterial activity against Enterococcus faecalis, Klebsiella pneumoniae, and Pseudomonas aeruginosa in Kirby-Bauer disc diffusion assay. They were also effective in inhibiting α-amylase and α-glucosidase enzymes, with AgNPs showing the highest % inhibitory potential than Met-Ext-D.L. These findings highlight the potential of AgNPs-D.L as effective agents in managing oxidative stress, bacterial infections, and diabetes, thereby supporting their use in developing new therapeutic formulations.