title: Actions of four organic acids in radix isatidis on endotoxin-neutralization investigated by kinetic turbidimetric assay.
abstract: OBJECTIVE
  To investigate anti-endotoxin action of four OAs reacted with endotoxin by the LAL assay with KTA.
  
  
  METHODS
  Using a incubating kinetic tube reader and kinetic turbidimetric assay (KTA), the concentration-response time curve of endotoxin reacted with limulus amebocyte lysate (LAL) at 37 degrees C were obtained and the action of four organic acids (OAs) on it were investigated. The four OAs were benzoic acid, salicylic acid, syringic acid and 2-amino-benzoic acid from Radix isatidis. Meanwhile, the temperature variation caused by endotoxin with the four OAs was studied by the rabbit pyrogen test (RPT).
  
  
  RESULTS
  It was showed that a low concentration (1 mg/mL) of the four OAs had a little effect of anti-endotoxin, and when the concentrations of the four OAs were 30 mg/mL, the endotoxin was neutralized completely. The relationships between the concentrations of endotoxin and the OAs were all linear with correlation coefficients of greater than 0.9995, indicating that the four OAs all had strong anti-endotoxin action, while syringic acid had the strongest action among the four OAs with IC50 of 12.84 mg/mL.
  
  
  CONCLUSIONS
  The investigations of KTA agreed well with the results obtained by means of RPT.
authors.affiliation: School of Traditional Chinese Medicine, Capital Medical University, Beijing 100069, China. marytjy66@yahoo.com.cn
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Ying-jun
authors.initials: YJ
authors.lastname: He
authors.forename: You
authors.initials: Y
authors.lastname: Li
authors.forename: Mu-xin
authors.initials: MX
authors.lastname: Gong
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D004731:Endotoxins / Q000037:antagonists & inhibitors*; D007700:Kinetics; D008297:Male; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D011817:Rabbits
chemical_list: D004365:Drugs, Chinese Herbal; D004731:Endotoxins; C540579:banlangen