title: Eucalrobusone C suppresses cell proliferation and induces ROS-dependent mitochondrial apoptosis via the p38 MAPK pathway in hepatocellular carcinoma cells.
abstract: BACKGROUND
  Eucalyptus extracts have anti-cancer activity against various cancer cells. Formyl-phloroglucinol meroterpenoids (FPMs), which are typical secondary metabolites of the genera Eucalyptus, have many important pharmacological activities.
  
  
  OBJECTIVE
  Eucalrobusone C (EC), a new bioactive phytochemical, was first isolated from the leaves of Eucalyptus robusta in our laboratory. EC is a FPM, and our previous research revealed that EC showed strongest cytotoxicity in three cancer models than other compounds isolated from the leaves of E. robusta. This study investigated its anti-tumor effects on human hepatocellular carcinoma (HCC) and its underlying mechanisms.
  
  
  METHODS
  Cell viability was measured by MTT assay. Cell cycle, apoptosis and mitochondrial transmembrane potential were determined by flow cytometry. Immunofluorescence was determined by a laser scanning confocal microscope. Protein levels were analyzed by Western blotting.
  
  
  RESULTS
  Our results showed that EC exerted strong anti-proliferative activity against HCC cells in a concentration- and time-dependent manner. EC markedly induced apoptosis through the caspase-dependent mitochondrial pathway, and the cell cycle was arrested at S phase. SB203580, a p38 MAPK inhibitor, effectively decreased cell death caused by EC. Moreover, the ROS scavenger N-acetyl cysteine (NAC) significantly attenuated apoptosis induced by EC and reversed EC-induced p38 MAPK activation.
  
  
  CONCLUSIONS
  Our findings indicate that EC induces mitochondrial-dependent apoptosis in HCC cells through ROS generation and p38 MAPK activation, making EC a promising candidate for further development as an anticancer agent for HCC cells.
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China.
authors.forename: Kai-Li
authors.initials: KL
authors.lastname: Jian
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China.
authors.forename: Zhi-Chun
authors.initials: ZC
authors.lastname: Shang
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China. Electronic address: dorothy19802003@gmail.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China. Electronic address: cpu_lykong@126.com.
authors.forename: Ling-Yi
authors.initials: LY
authors.lastname: Kong
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005052:Eucalyptus / Q000737:chemistry*; D056945:Hep G2 Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D011725:Pyridines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D007093:Imidazoles; D010936:Plant Extracts; D011725:Pyridines; D017382:Reactive Oxygen Species; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580
keywords: Eucalrobusone C; Human hepatocellular carcinoma; Mitochondrial pathway; ROS; p38 MAPK