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United States Department of Agriculture

Agricultural Research Service


item Buslig, Bela
item Manthey, John

Submitted to: National Meeting of Institute of Food Technologists/Food Expo
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2005
Publication Date: 7/21/2005
Citation: Buslig, B.S., Manthey, J.A. 2005. Furanocoumarins in grapefruit juice fractions. National Meeting of Institute of Food Technologists/Food Expo. Paper No. 104-6

Interpretive Summary:

Technical Abstract: Reported interactions between grapefruit (Citrus paradisi Macf.) juice and various prescription medications led investigators to suspect a variety of compounds present in grapefruit as responsible for these effects. These investigations amassed evidence that furanocoumarins (also known as psoralens), which are present in grapefruit, but lacking in most other citrus fruits, are mainly responsible for the observed effects. Various furanocoumarins were determined to be inhibitory to the enzymes in drug metabolism, but the exact mechanisms, quantitative effects and specific compounds are largely uncertain. The generally accepted enzyme systems implicated in the grapefruit-drug interactions are the cytochrome P450 enzymes (specifically the 3A4 isoform), present in both the intestinal wall and the liver, and the P-glycoprotein transporter in the intestinal wall. To establish the specific components responsible for the effects and the exact nature of the inhibition, it has been necessary to isolate and identify the various compounds implicated in earlier studies. To establish the best source for isolation of quantities of these compounds we prepared grapefruit juice, separated it into finished whole juice (~5% pulp), centrifuge retentate (~25% pulp), centrifuged supernatant (<1% pulp), and finisher pulp. The fractions were extracted with ethyl acetate and the furanocoumarin distribution in each fractions was determined with an LC/MS. Distribution of the furanocoumarins in the juice fractions will be discussed.

Last Modified: 06/24/2017
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