title: Evaluation of food-drug interaction of guava leaf tea.
abstract: Guava leaf tea (GLT) contains guava leaf polyphenol (Gvpp), which regulates the absorption of dietary carbohydrate from the intestines. Borderline diabetics, who are at high risk of development of diabetes, take GLT to suppress a rapid increase of blood sugar level after meals. However, patients with diabetes in whom diabetic drugs or warfarin as a blood thinner are prescribed also take GLT with the expectation of glycemic control. Therefore, we studied whether GLT had potential for inhibition or induction of cytochrome P450 (CYP) and an influence on the action of warfarin. Extract of guava leaf (GvEx) consists of carbohydrate and polyphenols, which are Gvpp, quercetin, and ellagic acid. These polyphenols, but not GvEx, showed a certain level of inhibition of human-cDNA-expressed CYPs. In a comparison of GLT and grapefruit juice, GLT showed weaker inhibition of CYP activities and of midazolam 1'-hydroxylation than grapefruit juice. Furthermore, neither liver weight nor CYP3A expression in the liver was changed in rats that received GvEx for 90 days compared with the control group. When rats were concomitantly treated with GLT and warfarin, the prolongation of clotting time of blood by warfarin was not influenced. These data suggest that GLT is unlikely to interact with drugs.
authors.affiliation: Safety Research Department, Yakult Central Institute for Microbiological Research. kimiyuki-kaneko@yakult.co.jp
authors.forename: Kimiyuki
authors.initials: K
authors.lastname: Kaneko
authors.forename: Katsuya
authors.initials: K
authors.lastname: Suzuki
authors.forename: Emi
authors.initials: E
authors.lastname: Iwadate-Iwata
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kato
authors.forename: Kazumi
authors.initials: K
authors.lastname: Uchida
authors.forename: Masaharu
authors.initials: M
authors.lastname: Onoue
mesh_terms: D000818:Animals; D001628:Beverages; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D065692:Cytochrome P-450 CYP3A Inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018565:Food-Drug Interactions; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008874:Midazolam / Q000378:metabolism; D010314:Partial Thromboplastin Time; D059808:Polyphenols / Q000494:pharmacology*; D031647:Psidium / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014859:Warfarin / Q000494:pharmacology*
chemical_list: D065692:Cytochrome P-450 CYP3A Inhibitors; D004791:Enzyme Inhibitors; D059808:Polyphenols; D014859:Warfarin; D051544:Cytochrome P-450 CYP3A; D008874:Midazolam