Journal of Medicinal Plants and By-products (2018) 1: 15-24 Original Article  Corresponding author: Department of Medicine, Faculty of Medicine, Qom Branch, Islamic Azad University, Qom, Iran Email Address: attaranhamidreza@yahoo.com Zataria multiflora Essential oil Prevent Iron Oxide Nanoparticles-induced Liver Toxicity in Rat Model Hamid Reza Attaran 1* , Faezeh Fatemi 2 , Azadeh Rasooli 3 , Abolfazl Dadkhah 4 , Mohammad Reza Mohammadi Malayeri 5 and Salome Dini 6 1 Department of Medicine, Faculty of Medicine, Qom Branch, Islamic Azad University, Qom, Iran 2 Materials and Nuclear Fuel Research School, Nuclear Science and Technology Research Institute, Tehran, Iran 3 Department of Biochemistry, Faculty of Sciences, Payame Noor University, Tehran, Iran 4 Department of Medicine, Faculty of Medicine, Qom Branch, Islamic Azad University, Qom, Iran 5 Department of Pathobiology, Faculty of Veterinary Medicine, Garmsar Branch, Islamic Azad University, Garmsar, Iran 6 Young Researchers and Elite Club, Karaj Branch, Islamic Azad University, Karaj, Iran Article History: Received: 22 May 2017 /Accepted in revised form: 29 November 2017 © 2013 Iranian Society of Medicinal Plants. All rights reserve Abstract Over loading of iron oxide nanoparticles can causes the liver injury through overproduction of free radicals. Zataria multiflora Boiss. (Lamiaceae) has been used for many years in folk medicine due to its antioxidant and antibacterial activities. This study evaluates -for the first time- the effect of Z. multiflora essential oil (EO) against iron oxide nanoparticles hepatotoxicity in rat model. Male Wistar rats were divided randomly into 4 groups; control group (C), non-treated control group (NT), treatment groups, nanoparticles plus Z. multiflora EO at 100 and 200 mg/kg b.w. In following, the liver and blood tissue were collected for estimating oxidative stress/antioxidant parameters including lipid peroxidation (LP), glutathione (GSH), glutathione-S-transferase (GST), and liver enzyme asparate transaminase (AST) and also histopathological examinations. Iron oxide nanoparticles toxicity produced a significant increase in the levels of LP, ferric reducing ability of plasma (FRAP), and AST activity concomitant with decrease in the levels of GSH and GST activity compared to the control group. However, in the treatment groups received Z. multiflora EO, the levels of LP and AST activity reduced together with increasing in GSH content and GST activity were significantly reported. Histopathological studies also supported the biochemical assessments indicating hepatic improvements induced by nanoparticles. Z. multiflora EO protected the liver from injuries induced by iron oxide nanoparticles which can be correlated with its antioxidant activities. This can be a valuable candidate in modulating the oxidative hepatic injuries. Keywords: Hepatotoxicity, Oxidative stress, Antioxidant parameters, Antioxidant agents Introduction A huge mass of biochemical functions and physiological roles of the liver makes it a crucial factor of health and a target in disease. Acute hepatic injury known as the most serious health problem worldwide is mainly caused by exposing to hepatotoxins, xenobiotics, and chemotherapeutic agents that lead to impairment of its functions [1]. Nanoparticles with very special feature (shape, size, and high proportion of surface to volume) including the elements of cobalt, iron, and nickel can easily enter into bloodstream thorough respiration and digestion systems [2]. Therefore, the liver can be seen as a target organ to identify