title: Glucuronidation and methylation of procyanidin dimers b2 and 3,3″-di-o-galloyl-b2 and corresponding monomers epicatechin and 3-o-galloyl-epicatechin in mouse liver.
abstract: OBJECTIVE
  The 3,3″-di-O-galloyl ester of procyanidin B2 (B2G2) is a component of grape seed extract that inhibits growth of human prostate carcinoma cell lines. In preparation for studies in mice, its hepatic metabolism was examined in vitro and compared to B2 and the corresponding monomers, epicatechin (EC) and 3-O-galloyl-epicatechin (ECG).
  
  
  METHODS
  Compounds were incubated with liver microsomes or cytosol containing cofactors for glucuronidation, sulfation or methylation, and products analyzed by liquid chromatography-mass spectrometry (LC-MS). B2G2 was administered orally to mice and plasma analyzed by LC-MS for unmodified procyanidin and metabolites.
  
  
  RESULTS
  Glucuronides and methyl ethers of B2 and B2G2 were formed in small amounts. In contrast, EC and ECG were largely or completely converted to glucuronides, sulfates and methyl ethers under the same incubation conditions. B2G2 given orally to mice was partially absorbed intact; no significant metabolites were detected in plasma.
  
  
  CONCLUSIONS
  Glucuronidation and methylation of procyanidins B2 and B2G2 occurred but were minor processes in vitro. B2G2 was partially absorbed intact in mice after oral dosing and did not undergo significant metabolism. Unlike the flavanol monomers EC and ECG, therefore, B2G2 bioavailability should not be limited by metabolism. These results paved the way for ongoing pharmacokinetic and efficacy studies.
authors: Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, Anschutz Medical Campus, MS C238, 12850 E. Montview Blvd., Aurora, Colorado, 80045, USA.
authors: Suraj P
authors: SP
authors: Shrestha
authors: John A
authors: JA
authors: Thompson
authors: Michael F
authors: MF
authors: Wempe
authors: Mallikarjuna
authors: M
authors: Gu
authors: Rajesh
authors: R
authors: Agarwal
authors: Chapla
authors: C
authors: Agarwal
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000378:metabolism*; D044946:Biflavonoids / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D002392:Catechin / Q000031:analogs & derivatives* / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D020719:Glucuronides / Q000378:metabolism*; D056604:Grape Seed Extract / Q000737:chemistry; D008297:Male; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL; D008862:Microsomes, Liver / Q000378:metabolism*; D044945:Proanthocyanidins / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D044946:Biflavonoids; D020719:Glucuronides; D056604:Grape Seed Extract; D044945:Proanthocyanidins; C479580:procyanidin B2; D002392:Catechin; C062669:epicatechin gallate