MOLECULAR MEDICINE REPORTS 13: 1019-1025, 2016 Abstract. Rhus javanica Linn, a traditional medicinal herb from the family Anacardiaceae, has been used in the treat- ment of liver diseases, cancer, parasitic infections, malaria and respiratory diseases in China, Korea and other Asian coun- tries for centuries. In the present study, the protective effects of R. javanica ethanolic extract (RJE) on hydrogen peroxide (H 2 O 2 )-induced oxidative stress in human Chang liver cells was investigated. The cell cytotoxicity and viability were assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The activities of superoxide dismutase (SOD) and catalase (CAT) were measured using respective enzymatic kits. Cell cycle analysis was performed using fow cytometric analysis. The protein expression levels of p53, B-cell lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax) and caspase-3 were assessed by western blotting. Human Chang liver cells were treated with different concentrations (0.1, 0.3 or 0.5 mg/ml) of RJE, and were subsequently exposed to H 2 O 2 (30 µM). Treatment with H 2 O 2 (30 µM) signifcantly induced cytotoxicity (P<0.05) and reduced the viability of the Chang liver cells. However, pretreatment of the cells with RJE (0.1, 0.3 or 0.5 mg/ml) signifcantly increased the cell viability (P<0.001 at 0.5 mg/ml) in a concentration-dependent manner following H 2 O 2 treatment. Furthermore, pretreat- ment with RJE increased the enzyme activities of SOD and CAT, and decreased the sub-G 1 growth phase of the cell cycle in response to H 2 O 2 -induced oxidative stress (P<0.001 at 0.3 and 0.5 mg/ml H 2 O 2 ). RJE also regulated the protein expression levels of p53, Bax, caspase-3 and Bcl-2. These results suggested that RJE may protect human Chang liver cells against oxidative damage by increasing the levels of antioxidant enzymes and regulating antiapoptotic oxidative stress mechanisms, thereby providing insights into the mecha- nism which underpins the traditional claims made for RJE in the treatment of liver diseases. Introduction The liver in vertebrates performs a number of vital functions, including metabolic and detoxifcation activities (1). Reactive oxygen species (ROS), generated under conditions of oxida- tive stress, are considered to be involved in the liver damage, which is induced under a variety of conditions, including alcohol abuse, fbrosis/cirrhosis, hepatocellular carcinoma, ischemia/reperfusion liver injury, paracetamol overdose and viral hepatitis (2). ROS are produced and degraded by all aerobic organisms, and exert beneficial effects, including cytotoxicity against bacteria and other pathogens during the maintenance of normal cell function. However, when ROS are present in excess, the state called ‘oxidative stress’ arises, which is associated with DNA damage, protein oxidation, carbonylation, lipid peroxidation, mitochondrial dysfunction, calcium homeostasis, actin reorganization, NAD depletion, impairment of energy metabolism and glutathione depletion in various cell types (3-5). To protect the human body against highly toxic ROS, various antioxidative stress mechanisms have been acquired, including an antioxidant defense system, which comprises intracellular antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), and gluta- thione (4,5). Hydrogen peroxide (H 2 O 2 ), one of the ROS molecules, is a by-product of oxidative stress, which is considered to act as a trigger of apoptosis in various cell types (3,6). Previous studies reported that H 2 O 2 -induced apoptotic cell death was associated with caspase-3 (7). Various processes activate apoptosis and, in particular, caspase-3 activation may ensure the effcient completion of apoptotic cell death (7). Therefore, Rhus javanica Linn protects against hydrogen peroxide‑induced toxicity in human Chang liver cells via attenuation of oxidative stress and apoptosis signaling CHANJIN YOON 1* , SUSHRUTA KOPPULA 2* , SEUNGHOON YOO 1 , MUNJEONG YUM 1 , JINSEOUB KIM 1 , JAEDONG LEE 3 and MINDONG SONG 2 1 Department of Applied Life Science, Graduate School of Konkuk University; 2 Department of Biotechnology, College of Biomedical and Health Sciences; 3 Department of Internal Medicine, School of Medicine, Konkuk University, Chungju, Chungbuk 380-701, Republic of Korea Received March 22, 2015; Accepted October 29, 2015 DOI: 10.3892/mmr.2015.4603 Correspondence to: Professor Mindong Song, Department of Biotechnology, College of Biomedical and Health Sciences, Konkuk University, U10 Danwol Dong Street, Chungju, Chungbuk 380-701, Republic of Korea E-mail: minds@kku.ac.kr * Contributed equally Key words: Rhus javanica, Gallunt, antioxidant, caspase, hepatitis, apoptosis