title: Steady-state pharmacokinetics and tissue distribution of anthraquinones of Rhei Rhizoma in rats.
abstract: OBJECTIVE
  Rhei Rhizoma, the rhizome of Rheum palmatum L. (RP), is a popular herb in clinical Chinese medicine. RP is abundant in polyphenolic anthraquinones, which have been reported to show various beneficial bioactivities. This study investigated the pharmacokinetics and tissue distribution of anthraquinones following seven-dose administration of RP decoction to rats.
  
  
  METHODS
  Six Sprague-Dawley rats were given 2.0 g/kg of RP twice daily for seven doses and blood samples were collected at designated time after the 7th dose. Another six rats were sacrificed at 30 min after the 7th dose and organs including liver, kidney, lung and brain were collected. Serum and tissue specimens were assayed by HPLC before and after hydrolysis with β-glucuronidase and sulfatase, respectively.
  
  
  RESULTS
  Pharmacokinetic analysis indicated that the anthraquinones in serum mainly presented as glucuronides/sulfates and contained higher ratio of sulfates when compared with single-dose administration of RP. Contrary to the finding in serum, tissue analysis discovered mainly free form of anthraquinone in most organs assayed, such as aloe-emodin and rhein in kidney, liver, lung; emodin in liver, lung; trace of chrysophanol in kidney and liver. In all brains, neither free forms nor their glucuronides/sulfates have been detected.
  
  
  CONCLUSIONS
  The glucuronides/sulfates of anthraquinones were the major forms in bloodstream, whereas the free forms of most anthraquinones were predominant in kidney and liver.
authors.affiliation: School of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan.
authors.forename: Chi-Sheng
authors.initials: CS
authors.lastname: Shia
authors.forename: Shang-Yuan
authors.initials: SY
authors.lastname: Tsai
authors.forename: Jung-Chih
authors.initials: JC
authors.lastname: Lin
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Li
authors.forename: Miau-Hwa
authors.initials: MH
authors.lastname: Ko
authors.forename: Pei-Dawn Lee
authors.initials: PD
authors.lastname: Chao
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Huang
authors.forename: Yu-Chi
authors.initials: YC
authors.lastname: Hou
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000880:Anthraquinones / Q000008:administration & dosage / Q000097:blood / Q000302:isolation & purification / Q000493:pharmacokinetics*; D001711:Biotransformation; D001921:Brain / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage / Q000302:isolation & purification / Q000493:pharmacokinetics*; D005966:Glucuronidase / Q000378:metabolism; D020719:Glucuronides / Q000378:metabolism; D006868:Hydrolysis; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012250:Rheum / Q000737:chemistry; D027343:Rhizome; D013429:Sulfatases / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D000880:Anthraquinones; D004365:Drugs, Chinese Herbal; D020719:Glucuronides; D013431:Sulfates; D013429:Sulfatases; D005966:Glucuronidase