Green Synthesis of Titanium Dioxide Nanoparticles Using Ethanolic Extract of Green Tea and Their Antioxidant Activities

The aim of this work is to prepare and study titanium dioxide nanoparticles (TiO₂ NPs) that were formed from the leaf extract of green tea using the green synthesis method. Plants were dried for seven days at room temperature and finely ground into a fine powder, after which chemical composition, HPLC analysis, characterization of TiO₂ NPs, and biological evaluation processes were performed. In addition, TiO₂ NPs synthesis was confirmed using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and highresolution–transmission electron microscope (HR–TEM). A close analysis indicates that the green tea extract contained polyphenols and flavonoids at varied levels, which may be responsible for its biological activities. HPLC examination indicates the presence of Gallic acid, Protocatechuic, p-hydroxybenzoic, Caffeine acid, Catechin, chlorogenic, rutin, coumaric acid, epicatechin gallate, apigenin-7-glucoside, ferulic acid, chrysin, quercetin, and cinnamic acid, might be responsible for their therapeutic potential. In vitro, antioxidant screening revealed that the scavenging effect of green tea extract has 50% inhibition (IC₅₀) at a concentration level of 19.64 ± 0.13 μg/mL, whereas standard Vit. C showed that at 16.81 ± 0.10 μg/mL. However, in the case of the ABTS model, the scavenging effect of green tea extract has 50% inhibition (IC50) at a concentration level of 33.47 ± 0.21 μg/mL, whereas standard Vit. C showed the same at 29.47 ± 0.17 μg/mL. These results demonstrate that green tea is an excellent antioxidant (i.e., an effective anti-DPPH compound).