M. Azizi - Department of Horticulture, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran.
H. Kaboli Farshchi - Department of Horticulture, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran.
F. Oroojalian - Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Islamic Republic of Iran.
H. Orafaee - Pharmaceutics Department, Faculty of Pharmacy, Mashhad University of Medical Science, Mashhad, Islamic Republic of Iran.

In this research Kelussia odoratissima Mozaff. leaf extract was used for the green synthesis of silver nanoparticles (AgNPs). At first we compared antioxidant activity of different extracts of K. odoratissima. Then solution containing silver nitrate was treated with the extract which showed high antioxidant activity. Synthesized AgNPs were evaluated by analyzing the excitation of surface plasmon resonance. TEM analysis was also used for nanoparticle characterization. Antibacterial activity of the solution containing AgNPs was measured by microdilution test. Common food contaminant bacteria such as gram-positive (Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes) and gram-negative (Escherichia coli O۱۵۷: H۷, Salmonella enterica and Pseudomonas aeruginosa)were used for the evaluation. The aqueous extract showed the highest antioxidant activity and the solution was used for the green synthesis of AgNPs. The particle diameters were calculated to be ۲۰-۴۰nm with -۱۷ to -۱۹.۹ mV zeta potential. The TEM micrographs showed that the AgNPs are nearly spherical in shape and highly monodispersed. MIC of the AgNPs against gram-positive and gram-negative bacteria was between ۰.۰۱۲-۰.۰۲۵ and ۰.۰۰۶-۰.۰۱۲ mg/ml respectively.

Kelussia odoratissima, Green Synthesis, silver nanoparticles, Antibacterial activity, Electron microscopy