Institute of Fundamental Technological Research

In the study, metabolites of Euphorbia sanguinea were used as benign reducing and stabilizing agents to obtain zinc oxide
nanoparticles (ZnO-NPs). The nanoparticles were evaluated as dual agent for photodegradation of Malachite green dye and
tyrosinase inhibitior of mushroom tyrosine enzyme. Surface plasmon bands and energy band gaps of the ZnO-NPs were
within the range 356–378 nm and 2.72–4.37 eV respectively as obtained from the UV–Vis spectra. SEM/EDS elemental
mapping of the nanoparticles gave flower-like shape and even distribution of zinc and oxygen. XRD result revealed crystallographic
peaks assigned to hexagonal phase of zinc oxide. The metal oxide nanoparticles were used to achieve 53% percentage
degradation of Malachite green dye solution in less than a minute of solar radiation, which increased to 92% in 60 min.
A first order kinetics with correlation coefficient R2
of 0.937, rate constant of 0.0084 min−1 and half-life of 82.52 min was
established for the photodegradation process. The ZnONPs exhibited good tyrosinase inhibition with IC50 of 49.016 μg/ml.
The mode of enzymatic inhibition was competitive with an inhibition constant (Ki) of 0.525 mM using Lineweaver–Burk
kinetic model.