Planta Med 2009; 75(4): 332-335
DOI: 10.1055/s-0028-1112210
Pharmacology
Letter
© Georg Thieme Verlag KG Stuttgart · New York

In vitro Interactions with Repeated Grapefruit Juice Administration – to Peel or not to Peel?

Shlomo Brill1 , 2 , Christian Zimmermann1 , Karin Berger3 , Juergen Drewe1 , Heike Gutmann1
  • 1Department of Clinical Pharmacology & Toxicology, University Clinic Basel, Basel, Switzerland
  • 2Department of Pharmacology; School of Pharmacy, University of London, London, UK
  • 3Vitaplant AG, Witterswil, Switzerland
Further Information

Publication History

Received: July 20, 2008 Revised: October 27, 2008

Accepted: November 4, 2008

Publication Date:
15 January 2009 (online)

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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 μM bergamottin and 200 μM 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.

References

Prof. Dr. Juergen Drewe

Department of Clinical Pharmacology and Toxicology

University Clinic Basel

Petersgraben 4

4031 Basel

Switzerland

Phone: +41-61-265-3848

Fax: +41-61-265-8581

Email: juergen.drewe@unibas.ch