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United States Department of Agriculture

Agricultural Research Service


item Widmer, Wilbur

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 5/16/2003
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: There has been considerable concern in the citrus industry over the last several years concerning the interaction between grapefruit juice and several prescription drugs. Grapefruit juice contains components which inhibit the intestinal enzyme CYP3A4. When CYP3A4 is inhibited, drugs normally metabolized by this enzyme are more bioavailable resulting in more of the affected drug being absorbed. The amount of grapefruit juice that must be ingested to completely inhibit the intestinal CYP3A4 has also been reported to vary. The most compelling evidence to date indicates that furanocoumarins and furanocoumarin dimer compounds present in grapefruit juice are largely or entirely responsible for the interactions. Juice from tangerine hybrids with grapefruit parentage along with 29 commercial red grapefruit and 30 white grapefruit juice products were analyzed for furanocoumarin and furanocoumarin dimer content. None of the tangerine hybrid juices were found to contain any furanocoumarins or furanocoumarin dimers. The variation in 6,7-dihydroxybergamottin (DHB) and bergamottin (BERG) content in the commercial grapefruit juices ranged from 0.2 - 7.6 ppm for DHB and 1.6 - 16.5 ppm for BERG with no relationship between content for these two components. While absolute quantization of furanocoumarin dimers was not possible because standards are not available, their content was found to vary between 20 and 60 fold between the commercial grapefruit juice products tested. Effects of grapefruit juice processing parameters on furanocoumarin content will also be discussed.

Last Modified: 07/26/2017
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