Abstract
The demand for natural sweeteners has been increasing; This trend is influenced by several factors, including concerns and controversies surrounding synthetic sweeteners. This study aims to determine the effect of elicitation with ZnO and MgO phytonanoparticles (PTNPs) on Stevia rebaudiana plants. The synthesis of PTNPs utilized the reduction potential of the natural aqueous extract derived from Moringa oleifera leaves. The characterization of the PTNPs was carried out by spectroscopic methods. Scanning electron microscope images of the ZnO PTNPs showed the presence of agglomerated rod-shaped nanoparticles, while the MgO PTNPs were irregularly shaped and agglomerated. Dynamic light scattering analysis showed an average size of 9-30 nm for ZnO PTNPs and 5-10 nm for MgO PTNPs, while zeta potential (ζ) values validated the stability of the PTNPs. The infrared spectra revealed bands corresponding to stretching vibrations of the bonds of the groups involved in the reduction and stabilization of PTNPs. The highest production of rebaudiosides A, E and M was obtained using 1 mg/L of ZnO PTNP. The elicitation with PTNPs mainly with ZnO from the concentration of 20 mg/L induces the production of molecules with antioxidant capacity, obtaining an increase of 137% of chlorogenic acid, while that of caffeic acid is 185%. These results indicated that the application of ZnO and MgO PTNPs induced a higher content of antioxidant compounds in Stevia rebaudiana.