Determination of the Antioxidant Activity of Calendula officinalis Extract and its Role in Synthesis of ZnO Nanoparticles

The synthesis of zinc oxide nanoparticles is valuable due to its applications in the packaging and food industries as permitted additives to increase the shelf life.

 In this research, the synthesis of green nanoparticles of zinc oxide were performed by zinc acetate dihydrate. Calendula officinalis extract was used as reducing and stabilizing agent. The prepared ZnO NPs were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Energy dispersive X- ray (EDX) and X-ray diffraction (XRD) analysis.

The size of nanoparticles prepared by Calendula officinalis extract was obtained at 8 to 22nm In addition, the antioxidant properties of prepared nanoparticles were analyzed in the terms of total phenolic and flavonoid content. The antioxidant activity of zinc oxide nanoparticles was evaluated using 2,2- diphenyl picryl hydrazyl (DPPH) method. Gallic acid was used as standard to draw the calibration curve. The amount of total phenolic compounds in aqueous extract of the plant was 303 mg of gallic acid per gram.

Calendula officinalis extract showed high antioxidant activity and great potential for green synthesis of nanoparticles. The average diameter of nanoparticles synthesized without   plant extract as a stabilizer, was larger than the green synthesized one (more than 18 nm). There was also less agglomeration in nanoparticles synthesized by Calendula officinalis extract.