title: Preliminary screening for extraction techniques and bioactive fraction of Coptidis Rhizoma based on microcalorimetry.
abstract: BACKGROUND
  Extraction techniques may alter the antibacterial activity of Coptidis Rhizoma (C. Rhizoma), which is regarded as characteristic of this herb.
  
  
  OBJECTIVE
  To explore the best extraction techniques of C. Rhizoma and the fraction(s) with the strongest antibacterial activity.
  
  
  METHODS
  Using microcalorimetry, the influence of different extraction fractions of C. Rhizoma obtained by decoction, reflux, and ultrasound techniques on Escherichia coli growth was investigated by analyzing the power-time curves and some thermokinetic parameters. Then the antibacterial activities of each fraction of C. Rhizoma were compared by analysis of variance (ANOVA). Meanwhile, the minimum inhibitory concentration (MIC) of the strongest antibacterial fraction was determined by 2-fold dilution method.
  
  
  CONCLUSIONS
  The petroleum ether (PE), chloroform (CHCl(3)), ethyl acetate (EtOAc), and n-butyl alcohol (n-BuOH) fraction, water extract, and the residue after extraction all inhibited the growth of E. coli. The potency of the inhibitory effects was as follows: n-BuOH fraction > EtOAc fraction > CHCl(3) fraction > PE fraction > residue after extraction > water extract. The decoction technique was regarded as the optimum extraction technique. The n-BuOH fraction from the decoction technique was observed to have the strongest antibacterial fraction with half-inhibitory concentration IC(50) of 1.68 mg/mL and MIC of 200 μg/mL.
authors.affiliation: Pharmacy College, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan. kongwj302@126.com
authors.forename: Wei-Jun
authors.initials: WJ
authors.lastname: Kong
authors.forename: Zun-Lun
authors.initials: ZL
authors.lastname: Li
authors.forename: Xiao-He
authors.initials: XH
authors.lastname: Xiao
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Zhao
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002151:Calorimetry; D039323:Coptis / Q000737:chemistry*; D000089042:Coptis chinensis; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D027343:Rhizome
chemical_list: D000900:Anti-Bacterial Agents; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; C107393:Coptidis rhizoma extract