title: [Oral acute toxicity of (+)-usnic acid in mice and its cytotoxicity in rat cardiac fibroblasts].
abstract: OBJECTIVE
  To observe the oral acute toxicity of of (+)-usnic acid in mice and assess its cytotoxicity in rat cardiac fibroblasts.
  
  
  METHODS
  The mice with acute poisoning of (+)-usnic acid at different doses by oral administration were observed for toxic manifestations, and the LD(50) was determined. The survival time and survival rate of the mice receiving different doses of (+)-usnic acid were observed. Cultured rat cardiac fibroblasts were inoculated with different concentrations of (+)-usnic acid, and the cell growth inhibition rate was estimated and the IC(50) determined using MTT assay.
  
  
  RESULTS
  Higher dose of (+)-usnic acid resulted in more obvious symptoms of poisoning and shorter survival time of the mice. The LD(50) of (+)-usnic acid in mice by oral administration was 388 mg/kg. The manifestations of poisoning such as apathism, pilomotor, chill, dyspnea, torpidity and anorexia was observed. Rat cardiac fibroblasts incubated with (+)-usnic acid showed obvious growth inhibition, which was positively correlated to the dose of (+)-usnic acid, and high dose of (+)-usnic acid caused severe cell injuries. The IC(50) of (+)-usnic acid in rat cardiac fibroblasts was 322 microg/ml.
  
  
  CONCLUSIONS
  (+)-usnic acid is a natural compound of low toxicity in mice, and low to medium dose of (+)-usnic acid dose not produce obvious cytotoxicity.
authors.affiliation: Department of Immunology, Xi'an Jiaotong University College of Medicine, Xi'an 710061, China. chengyb@mail.xjtu.edu.cn
authors.forename: Yan-bin
authors.initials: YB
authors.lastname: Cheng
authors.forename: Lin-lin
authors.initials: LL
authors.lastname: Wei
authors.forename: Ning
authors.initials: N
authors.lastname: Gu
authors.forename: Kai-wei
authors.initials: KW
authors.lastname: Si
authors.forename: Lin
authors.initials: L
authors.lastname: Shi
authors.forename: Xiao-qi
authors.initials: XQ
authors.lastname: Li
authors.forename: Chen
authors.initials: C
authors.lastname: Li
authors.forename: Yu-kang
authors.initials: YK
authors.lastname: Yuan
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001572:Benzofurans / Q000008:administration & dosage / Q000737:chemistry* / Q000633:toxicity*; D005347:Fibroblasts / Q000187:drug effects*; D007928:Lethal Dose 50; D051379:Mice; D009206:Myocardium / Q000166:cytology*; D051381:Rats; D013237:Stereoisomerism
chemical_list: D001572:Benzofurans; C073339:usnic acid