title: The effects of green tea polyphenols on drug metabolism.
abstract: BACKGROUND
  Tea, made from the dried leaves of the plant Camellia sinensis Theaceae, is a very popular beverage consumed worldwide. Recently, green tea extract-based dietary supplements have also been widely consumed for the acclaimed beneficial health effects, such as weight reduction. Although tea consumption is considered to be innocuous, the potential interactions between tea polyphenols and drugs have been demonstrated in studies in vitro and in vivo.
  
  
  METHODS
  This article reviews the current literature on the chemistry and biotransformation of tea constituents, mainly catechins from green tea. The article also provides a review of their effects on the absorption, efflux, metabolism and elimination of different drugs.
  
  
  CONCLUSIONS
  Tea catechins may bind to certain drugs to affect their absorption and bioactivities. Tea catechins may inhibit the activities of drug-metabolizing enzymes and drug transporters or affect the expression of these proteins, either upregulation or downregulation. Although these effects have been demonstrated in studies in vitro and in animal models, such effects have only been observed in limited cases in humans at common doses of human tea consumption. The ingestion of tea catechins from dietary supplements, which could be in large bullet doses, may produce more profound effects on drug metabolism, and such effects with drugs need to be further investigated.
authors.affiliation: The State University of New Jersey, Ernest Mario School of Pharmacy, Department of Chemical Biology, Rutgers, Piscataway, NJ 08854-8020, USA. csyang@pharmacy.rutgers.edu
authors.forename: Chung S
authors.initials: CS
authors.lastname: Yang
authors.forename: Eva
authors.initials: E
authors.lastname: Pan
mesh_terms: D000042:Absorption; D000818:Animals; D001682:Biological Availability; D001711:Biotransformation / Q000187:drug effects; D004798:Enzymes / Q000378:metabolism; D041743:Herb-Drug Interactions; D006801:Humans; D049990:Membrane Transport Modulators / Q000302:isolation & purification / Q000494:pharmacology*; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves; D010946:Plants, Medicinal; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology*; D013662:Tea / Q000737:chemistry
chemical_list: D004798:Enzymes; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins; D010936:Plant Extracts; D059808:Polyphenols; D013662:Tea