Biofabricated Zinc Oxide Nanoparticles (ZnONPs) using Annona stenophylla: Their Structural and Activity Characterization

Biosynthesis of functional nanomaterials from metallic salts using polyphenolic components of plant extracts provides an eco-friendly, easily scalable one pot fabrication of novel biotherapeutics. Among the nanomaterials that can be obtained through green synthesis, Zinc Oxide nanoparticles (ZnONPs) have shown considerable potential in the management of type 2 diabetes mellitus which is a global scourge affecting more than 50% of the adult population at some point in their lives. Annona stenophylla (A. stenophylla), a native Southern African dwarf tree has been widely used in traditional medicine as a remedy for diabetes. Its use is supported by numerous scientific studies that have validated its hypoglycaemic effects in vitro. Thus, the main objective of this work was to investigate the phytoconstituents of A. stenophylla and their capacity to mediate in the biosynthesis of ZnONPs as reducing, capping and stabilising agents. The nanostructures obtained were characterised by Transmission electron microscopy (TEM), UV -Vis spectrometry and Dynamic light scattering (DLS). The acute oral toxicity of the lyophilised root extract was also determined in a rat model. The participation of polyphenols in the synthesis was confirmed by spectral absorbance around 270nm. The presence of the biogenic ZnONPs was confirmed by UV-Vis spectra showing absorbance around 370nm. The synthesized nanostructures appeared mostly spherical in morphology, and the particle sizes were in the range of 40 to 60nm. No toxicity was observed at dosages up to 2000mg/kg body weight of the lyophilised A stenophylla extracts. The findings demonstrate the feasibility of fabricating ZnONPs from the polyphenolic constituents of the A. stenophylla root extract. In conclusion, safe biogenic ZnONPs were successfully synthesized from A. stenophylla which can potentially offer an opportunity to combine anti-diabetic metallic oxides and traditional medicines in novel, effective and eco-friendly dosage forms.