title: In vitro interactions with repeated grapefruit juice administration--to peel or not to peel?
abstract: Interactions of acutely administered grapefruit juice (GFJ) with cytochrome P450 isoform 3A4 (CYP3A4) and P-glycoprotein (Pgp) function are well established. In this study, we investigated in vitro the effect of repeated administration of GFJ and its major constituents (the flavonoid naringin, its aglycone naringenin and the furanocoumarin bergamottin) on mRNA expression of MDR1 and CYP3A4 in LS180 cells. Since the bergamottin content is higher in the peel than in the fruit, we compared GFJ containing peel (GFJP+) with juice without any peel extract (GFJP-). GFJP- (1%) showed no significant effect on MDR1 and CYP3A4 mRNA expression, whereas 1% GFJP+ increased expression of MDR1 3.7-fold (P<0.01) and CYP3A4 2.3-fold (P<0.05). Of the tested constituents, only 10 microM bergamottin and 200 microM naringenin induced MDR1 mRNA levels 2.9- and 4.0-fold, respectively (P<0.01 for both), and CYP3A4 mRNA levels 3.2- and 15.6-fold (P<0.01 for both), respectively. Western blot analysis and rhodamine 123 uptake experiments partly confirmed these findings on the protein and the functional level. In summary, GFJ containing no peel extract may have a lower potential for interactions with CYP3A4 or P-glycoprotein.
authors.affiliation: Department of Clinical Pharmacology & Toxicology, University Clinic Basel, Basel, Switzerland.
authors.forename: Shlomo
authors.initials: S
authors.lastname: Brill
authors.forename: Christian
authors.initials: C
authors.lastname: Zimmermann
authors.forename: Karin
authors.initials: K
authors.lastname: Berger
authors.forename: Juergen
authors.initials: J
authors.lastname: Drewe
authors.forename: Heike
authors.initials: H
authors.lastname: Gutmann
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D001628:Beverages / Q000009:adverse effects*; D045744:Cell Line, Tumor; D032083:Citrus paradisi / Q000737:chemistry*; D051544:Cytochrome P-450 CYP3A; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004347:Drug Interactions; D005638:Fruit / Q000737:chemistry; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D012333:RNA, Messenger; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human