Antiviral Research 89 (2011) 35–42 Contents lists available at ScienceDirect Antiviral Research journal homepage: www.elsevier.com/locate/antiviral Anti-hepatitis C virus activity of Acacia confusa extract via suppressing cyclooxygenase-2 Jin-Ching Lee a,b,∗ , Wei-Chun Chen a,1 , Shou-Fang Wu b,1 , Chin-kai Tseng a , Ching-Yi Chiou b , Fang-Rong Chang b , Shih-hsien Hsu c , Yang-Chang Wu b,d,e,∗ a Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC b Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC c Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC d Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan, ROC e Natural Medicinal Products Research Center, China Medical University Hospital, Taichung, Taiwan, ROC article info Article history: Received 15 July 2010 Received in revised form 14 October 2010 Accepted 4 November 2010 Keywords: Acacia confusa Hepatitis C virus Cyclooxygenase-2 Nuclear factor-kappaB abstract Chronic hepatitis C virus (HCV) infection continues to be an important cause of morbidity and mortality by chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) throughout the world. It is of tremendous importance to discover more effective and safer agents to improve the clinical treatment on HCV carriers. Here we report that the n-butanol–methanol extract obtained from Acacia confusa plant, referred as ACSB- M4, exhibited the inhibition of HCV RNA replication in the HCV replicon assay system, with an EC 50 value and CC 50 /EC 50 selective index (SI) of 5 ± 0.3 g/ml and >100, respectively. Besides, ACSB-M4 showed antiviral synergy in combination with IFN- and as HCV protease inhibitor (Telaprevir; VX-950) and polymerase inhibitor (2 ′ -C-methylcytidine; NM-107) by a multiple linear logistic model and isobologram analysis. A complementary approach involving the overexpression of COX-2 protein in ACSB-M4-treated HCV replicon cells was used to evaluate the antiviral action at the molecular level. ACSB-M4 significantly suppressed COX-2 expression in HCV replicon cells. Viral replication was gradually restored if COX-2 was added simultaneously with ACSB-M4, suggesting that the anti-HCV activity of ACSB-M4 was associated with down-regulation of COX-2, which was correlated with the suppression of nuclear factor-kappaB (NF-B) activation. ACSB-M4 may serve as a potential protective agent for use in the management of patients with chronic HCV infection. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved. 1. Introduction Hepatitis C virus (HCV) is an enveloped, positive-stranded RNA virus belonging to the family Flaviviridae (Lindenbach and Rice, 2005). It has a 9.6-kb genome encoding a single polyprotein that is subsequently cleaved by both host and virus protease into at least 10 mature individual proteins: four structural proteins (C, E1, E2, and p7) and six nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A and NS5B) (Penin et al., 2004). Approximately 170 mil- lion people worldwide are chronically infected with HCV, which is leading cause of chronic hepatitis, cirrhosis, and hepatocellu- lar carcinoma (HCC) (Alter, 2007; Levrero, 2006). To date, there ∗ Corresponding authors at: Department of Biotechnology, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, San Ming District, 807 Kaohsiung City, Taiwan, Republic of China. Tel.: +86 886 7 312 1101x2369; fax: +86 886 7 312 5339. E-mail addresses: jclee@kmu.edu.tw (J.-C. Lee), yachwu@mail.cmu.edu.tw (Y.-C. Wu). 1 These authors contributed equally to this work. is no prophylactic vaccine available to prevent HCV infection. The current standard of care for chronic hepatitis C involves the admin- istration of pegylated interferon- (IFN-) in combination with the nucleoside analog ribavirin (Ferenci, 2006). However, this regimen has an unfavorable side-effect profile (including flu-like symptoms, hemolytic anemia, and depression), which often leads to discontin- uance of therapy (Schaefer and Mauss, 2008). Thus, there is a strong medical need to discover novel agents with a high therapeutic index and few side-effects to treat chronic HCV infection. Constitutive NF-B activation, caused by infection with viruses, is recognized as a risk factor for virally induced hepatic failure due to chronic inflammation or proliferation of hepatoma cells (Sun and Karin, 2008). Cyclooxygenase-2 (COX-2) is a critical NF-B- mediated factor that participates in inflammatory disorders and is associated with human cancer (Pikarsky et al., 2004; Tang et al., 2005). Recent studies have shown that HCV proteins, including core, E2, NS3 and NS5A, promote the improper up-regulation of hepatic NF-B and COX-2 signaling pathway leading to HCC (Lu et al., 2008; Nunez et al., 2004; Waris and Siddiqui, 2005). Thus, the NF-B–COX-2 signaling pathway represents a pharmacological 0166-3542/$ – see front matter. Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.antiviral.2010.11.003