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item Buslig, Bela
item Manthey, John

Submitted to: Subtropical Technology Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/2004
Publication Date: 10/21/2004
Citation: Buslig, B.S., Manthey, J.A. 2004. Distribution of furanocoumarins in grapefruit juice. Subtropical Technology Conference Proceedings. 55:29.

Interpretive Summary:

Technical Abstract: During the past several years interactions were reported between prescription medications and grapefruit juice. The generally accepted enzymes implicated in the grapefruit-drug interactions are the cytochrome P450 3A4 isoform, in both the intestinal wall and the liver, and the P-glycoprotein transporter in the intestinal wall. The primary compounds responsible for these interactions are thought to be various furanocoumarins, also known as psoralens. The furanocoumarins were determined to be inhibitory to these enzymes, but the exact mechanisms and compounds are still uncertain. To determine 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. The furanocoumarin content of whole juice (~5% pulp), centrifuge retentate (~25% pulp), centrifuged supernatant (<1% pulp), and finisher pulp of white Marsh grapefruit was determined. Ethyl acetate extracts of each sample were analyzed by LC/MS and the peaks were classified by a combination of UV and ESI mass spectral characteristics. The distribution of the components, monitored at 310 nm for furanocoumarins was shown. Results indicate that the highest concentrations of furanocoumarins are located in the particulate fraction of the juice (centrifuge retentate), with bergamottin as the primary furanocoumarin. The retentate also contained some dimeric furanocoumarins, which eluted close to or after the bergamottin peak. The supernatant fraction contained a small amount bergamottin, and no detectable quantities of dimeric compounds, the major furanocoumarin being dihydroxybergamottin. The finisher pulp contained all of the components found in the retentate, but the concentrations were considerably lower.