Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2005
Publication Date: 5/1/2005
Citation: Widmer, W.W., Haun, C. 2005. Variation in furanocoumarin content and new furanocoumarin dimers in commercial grapefruit (Citrus paradisi, marcf.) juices. Journal of Food Science. 70(4):C307-312. Interpretive Summary: Grapefruit sales and crop value have declined during the last decade. One reason is from a concern about possible drug interactions. There are compounds in grapefruit juice that inhibit an enzyme in the human intestine which breaks down some drug medications. When this happens more of the drug is absorbed and can be a health concern. It is fairly well accepted after more than a decade of research that the components responsible are a class of compounds called furanocoumarins or psorelans. Commercial grapefruit juice samples were collected from the market over a two year period and the furanocoumarin content measured. Furanocoumarin content varied considerably in the commercial sample and additional studies are being conducted which are measuring furanocoumarin components in different varieties of grapefruit and how they change as the fruit matures.
Technical Abstract: Grapefruit sales and crop value have declined during the last decade. One reason is from a concern about possible drug interactions. Coadministered grapefruit increases the bioavailability of some medicines because it contains furanocoumarins that inhibit an intestinal enzyme (cytochrome P450-3A4 or CYP3A4) that normally metabolizes these drugs. Only drugs metabolized by intestinal CYP3A4 are significantly affected when taken with grapefruit juice, but the magnitude of the effect varies considerably between studies indicating that there are differences in the amount of components responsible for CYP3A4 inhibition in commercial grapefruit juices. It is becoming well accepted after more than a decade of research that furanocoumarins are the components largely responsible for the interaction. To access the variation in furanocoumarins present, content of 6,7-dihydroxybergamottin, bergamottin, and several furanocoumarin dimers were determined in 60 commercial grapefruit juices collected over 2 seasons. Bergamottin ranged from 1.6 to 16.5 ppm, 6,7-dihydroxybergamottin ranged from 0.2 to 11.2 ppm. Individual furanocoumarin dimers, present in lower amounts, but reported to be much more active CYP3A4 inhibitors, were found to vary up to 60 fold between juices.