Abstract:
This study reports the green synthesis of zinc oxide nanoparticles (SL-ZnONPs) using an aqueous leaf extract of Syzygium laetum (Buch.-Ham.) Gandhi, a riverine endemic from the Western Ghats, via a solution combustion method. The synthesised SL-ZnONPs displayed a surface plasmon resonance peak at 371 nm and exhibited a direct band-gap energy of 2.6 eV. Dynamic light scattering analysis revealed an average hydrodynamic diameter of 54.3 nm, with a polydispersity index of 0.448 and a zeta potential of -15.04 mV, indicating moderate colloidal stability. Fourier transform infrared (FT-IR) spectroscopy confirmed the role of phenolic and carbonyl groups in reducing and stabilising SL-ZnONPs. X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), and transmission electron microscopy (FEG-TEM) confirmed a hexagonal Wurtzite structure with an average crystallite size of 26.952 nm and particle size of 17.92 plus-minus 0.6 nm. The SL-ZnONPs showed strong antioxidant activity, with IC sub(50) values of 89.96 Mu g/mL in the DPPH and 68.1 Mu g/mL in the ABTS assay. SL-ZnONPs showed notable cytotoxic effects on MCF-7 cells (IC sub(50) = 7.02 Mu g/mL) and HeLa cells (IC sub(50) = 81.19 Mu g/mL), while remaining less toxic towards HEK-293 cells (IC50 = 224.9 Mu g/mL). Enzyme inhibition studies indicated inhibition of Alpha-amylase and Alpha-glucosidase, with IC sub(50) values of 77.10 and 86.80 Mu g/mL, respectively. Furthermore, SL-ZnONPs decreased intracellular lipid accumulation in 3T3-L1 cells, confirming its antidiabetic potential. Anti-inflammatory studies showed significant membrane stabilisation and reduced protein denaturation, reflected in IC sub(50) values of 37.09 and 40.29 Mu g/mL respectively. An ecotoxicity assessment with Danio rerio embryos indicated no significant developmental toxicity at doses up to 200 Mu g/mL. Overall, these findings underscore the potential of SL-ZnONPs as an eco-friendly nanoplatform with promising biomedical and therapeutic uses.
