Flavonoid in grapefruit

Hagen et a/L (42) determined the relative amounts of all the flavanone glycosides in Texas grapefruit. Their results are shown in Table III. Naringin is the dominant flavonoid in grapefruit and is primarily responsible for the immediate bitter taste in grapefruit. The equally bitter poncirin and the much less bitter neohesperidin are present in relatively small amounts and do not contribute significantly to overall bitterness. 

CALCIUM CHANNEL BLOCKERS GRAPEFRUIT JUICE t bioavailability of felodipine and nisoldipine (with reports of adverse effects), and t bioavailability of isradipine, lacidipine, lercanidipine, nicardipine, nifedipine, nimodipine and verapamil (without reported adverse clinical effects) Postulated that flavonoids in grapefruit juice (and possibly Seville oranges and limes) inhibit intestinal (but not hepatic) CYP3A4. They also inhibit intestinal P-gp, which may t the bioavailability of verapamil Avoid concurrent use of felodipine and nisoldipine and grapefruit juice... 

Naringin is the predominant flavonoid in grapefruit. It is distinguished readily from hesperidin by its extreme bitterness, which it sometimes imparts to grapefruit products. Naringin is used in the preparation of beverages and to enhance the piquant flavor of high class confections. 

Koca U (2007) Elevation of the flavonoid content in grapefruit by introducing chalcone isomerase gene via biotechnological methods. Turk J Pharm Sci 4(3) 115-124... 

Raymond WR, Maier VP (1977) Chalcone cyclase and flavonoid biosynthesis in grapefruit. Phytochemistry 16 1535-1539... 

Bronner, W.E. and Beecher, G.R., Extraction and measurement of prominent flavonoids in orange and grapefruit juice concentrates, J. Chromatogr. A, 705, 247, 1995. 

WJ Hsu, M Berhow, GH Robertson, S Hasegawa. Limonoids and flavonoids in juices of Oroblance and Melogold grapefruit hybrids. J Food Sci 63 57-60, 1998. 

Direct ultraviolet spectrophotometric methods have been developed to measure naringin in grapefruit (19J and hesperidin in orange juice (20, 21j. While these methods are rapid, they are also nonspeciTTc for flavonoid bitterness. 

Several TLC methods have been widely used to quantitatively estimate the flavonoids for quality control purposes rather than to detect adulteration. The potential exists, however, for testing authenticity. Naringin is an important compound in grapefruit juice, since it is largely responsible for the bitter character of the juice. Fisher et al. (121) developed a TLC procedure for naringin estimation. This was later modified by Tatum and Berry (122). Swift (123) developed a TLC-spectrophotometric assay for the neutral methoxylated flavones in orange peel. The method was subsequently expanded to the determination of these compounds in orange juice (124). 

Vanamala J, Reddivari L, Yoo KS, Pike LM and Patil BS, Variation in the content of bioactive flavonoids in different brands of orange and grapefruit juices. J Food Comp Anal 19 157-166 (2006). 

Castro, W.V.D. Mertens-Talcott, S. Rubner, A. Butterweck, V. Derendorf, H. 2006. Variation of flavonoids and furanocoumarins in grapefruit juices a potential source of variability in grapefruit juice—drug interaction studies. J. Agric. Food Chem. 54 249-255. 

Girennavar, B. Jayaprakasha, G.K. John, L.J. Path, B.S. 2008a. Variation of bioactive furocoumarins and flavonoids in different varieties of grapefruits and pummelo. Eur. Food Res. Tech. 226 1269 1275. 

Ribeiro, I.A. Ribeiro, M.H.L. 2008. Naringin and naringenin determination and control in grapefruit juice by a validated HPLC method. Food Control 19 432-438. Rice-Evans, C.A. Miller, N.J. Paganga, G. 1996. Structure-antioxidant activity relationships of flavonoids and phenolic acids. Free Radic. Biol. Med. 20 933-956. Rietjens, I.M.C.M. Boersma, M.G. Haan, L.D. Spenkelink, B. Awad, H.M. Cnubhen, N.H.P. van Zanden, J.J. Woude, H.V.D. Alink, G.M. Koeman, J.H. 

Of the several hundred chemical entities in grapefruit juice (8), psoralens, mainly 6,7-dihydroxybergamottin, are thought to be the components in grapefruit that are responsible for these interactions, although the flavonoid naringenin, which was originally suspected, cannot be excluded and may have a minor role (9). 

Miniscalco A,Lundahl J, GunnarRegardh C, Edgar B, Eriksson UG. 1992. Inhibition of dihydropyridine metabolism in rat and human liver microsomes by flavonoids found in grapefruit juice. J. Pharmacol. Exp. Ther. 261 1195-99... 

Early (not quite mature) citrus juices, lemon, Hamlin and Navel juices can develop the so-called limonin-bittemess. Additionally, there can also be a flavonoid-induced bitterness, like naringin in grapefruit juice. Adsorber resin treatment can successfully eliminate this bitterness below the detectable limit. See also [20]. 

Fig. 2.26 A characteristic furocoumaiin (bergamottin), a limonoid (nomilin) and polyphenolic compound (the flavonoid hesperidin) described in grapefruit and the synthetic benzethonium chloride—no chemical relationship. (Authors own work)...

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