title: Betulinic acid exerts anti-hepatitis C virus activity via the suppression of NF-κB- and MAPK-ERK1/2-mediated COX-2 expression.
abstract: OBJECTIVE
  This study was designed to evaluate the effect of betulinic acid (BA), extracted from Avicennia marina, on the replication of hepatitis C virus (HCV) and to investigate the mechanism of this BA-mediated anti-HCV activity.
  
  
  METHODS
  HCV replicon and infectious systems were used to evaluate the anti-HCV activity of BA. Exogenous COX-2 or knock-down of COX-2 expression was used to investigate the role of COX-2 in the anti-HCV activity of BA. The effects of BA on the phosphorylation of NF-κB and on kinases in the MAPK signalling pathway were determined. The anti-HCV activity of BA in combination with other HCV inhibitors was also determined to assess its use as an anti-HCV supplement.
  
  
  RESULTS
  BA inhibited HCV replication in both Ava5 replicon cells and in a cell culture-derived infectious HCV particle system. Treatment with a combination of BA and IFN-α, the protease inhibitor telaprevir or the NS5B polymerase inhibitor sofosbuvir resulted in the synergistic suppression of HCV RNA replication. Exogenous overexpression of COX-2 gradually attenuated the inhibitory effect of BA on HCV replication, suggesting that BA reduces HCV replication by suppressing the expression of COX-2. In particular, BA down-regulated HCV-induced COX-2 expression by reducing the phosphorylation of NF-κB and ERK1/2 of the MAPK signalling pathway.
  
  
  CONCLUSIONS
  BA inhibits HCV replication by suppressing the NF-κB- and ERK1/2-mediated COX-2 pathway and may serve as a promising compound for drug development or as a potential supplement for use in the treatment of HCV-infected patients.
authors.affiliation: Doctoral Degree Program in Marine Biotechnology, College of Marine Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Chun-Kuang
authors.initials: CK
authors.lastname: Lin
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Center of Infectious Disease and Signaling Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chin-Kai
authors.initials: CK
authors.lastname: Tseng
authors.affiliation: Department of Marine Biotechnology and Resources, College of Marine Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Kai-Hsun
authors.initials: KH
authors.lastname: Chen
authors.affiliation: Doctoral Degree Program in Marine Biotechnology, College of Marine Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.|Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
authors.forename: Shih-Hsiung
authors.initials: SH
authors.lastname: Wu
authors.affiliation: Doctoral Degree Program in Marine Biotechnology, College of Marine Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.|Department of Marine Biotechnology and Resources, College of Marine Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Chih-Chuang
authors.initials: CC
authors.lastname: Liaw
authors.affiliation: Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan.|Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jin-Ching
authors.initials: JC
authors.lastname: Lee