In vitro and Molecular Docking Evaluation of the Antibacterial, Antioxidant, and Antidiabetic Effects of Silver Nanoparticles from Cymbopogon citratus Leaf

Diabetes and multidrug-resistant (MDR) bacterial infections remain very common worldwide. This study investigated the antioxidant, antibacterial, and antidiabetic potentials of silver nanoparticles (AgNPs) from Cymbopogon citratus aqueous leaf extract (CCALE). AgNPs were synthesized in a 9:1 of 1 mM AgNO3 solution to CCALE. The synthesis was monitored via colour change and UV-visible spectrophotometry and later characterized using Fourier transform infrared spectroscopy (FTIR), energy dispersive x-ray (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Using standard procedures, gaschromatography-mass spectrometry (GC-MS) and antioxidant assays (reducing power, ferric reducing antioxidant power, total antioxidant capacity, and DPPH radical scavenging) of AgNPs were performed. Antibacterial activities against MDR bacterial isolates were assessed using the agar-diffusion method. Molecular docking studies were conducted using PyRx and Biovia Discovery Studio with 3D conformers of CCALE phyto-compounds retrieved from PubChem and 11-β-hydroxysteroid and Vaspin proteins from the RCSB Protein Data Bank. The AgNPs showed a light brown colour and a UV-Vis absorption peak at 445 nm. TEM revealed spherical particles (9.22 to 12.54 nm). EDX confirmed significant silver content. FTIR indicated the presence of alkynes, carboxylic acids, and alcohol groups. XRD showed diffraction peaks at 2θ = 38°, 44.5°, and 64.5°, corresponding to the (111), (200), and (220) reflection planes. TGA indicated volatility and thermal stability. The AgNPs demonstrated strong antioxidant and antibacterial activities, particularly against Klebsiella pneumoniae, Salmonella typhi, and Staphylococcus aureus. Stigmasterol exhibited the best binding affinity with the protein targets, suggesting CCALEAgNPs as a potential antioxidant, antibacterial, and antidiabetic drug candidate.