Grapefruit flavonoid

Ho PC, Saville DJ, Wanwimolruk S. Inhibition of human CYP3A4 activity by grapefruit flavonoids, furanocoumarins and related compounds. J Pharm Pharm Sci 2001 4(3) 217-227. 

Borradaile, N. M., de Dreu, L. E., Barrett, P. H., Behrsin, C. D., Huff, M. W. (2003). Hepato-cyte apoB-containing lipoprotein secretion is decreased by the grapefruit flavonoid, naringenin, via inhibition of MTP-mediated microsomal triglyceride accumulation. Biochemistry, 42, 1283-1291. 

Fukuda, K.,Ohra, T. 8cYamazoe,Y. (1997). Grapefruit component interacting with rat andhuman P450 CYP3A possible involvement on non-flavonoid components in drug interaction. Biol. Pharm. Bull, 20, 560-4. 

Luck, S., Kiesecker, C., Thomas, D., Kathofer, S., Niroomand, F., Kiehn, J., Kreye, V.A., Katus, H.A., Schoels, W. and Karle, C.A. (2005) QTc prolongation by grapefruit juice and its potential pharmacological basis HERG channel blockade by flavonoids. Circulation, 111, 835-838. 

In an attempt to influence flavor characteristics, CHS antisense and overexpression constructs were introduced into grapefruit by Agrobacterium tumefaciens [16, 59]. CHS overexpression constructs were shown to lead to morphological abnormalities and frequently to death, while a number of CHS antisense constructs resulted in a statistically significant reduction in flavonoid content in the transgenic plants even though there was a large variation in the flavonoid concentration [16]. 

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... 

HPLC-ESI Flavonoids of lemon, grapefruit, bergamot, orange, and mandarin Bcl-2 antisense... 

Ross, S.A. et al., Variance of common flavonoids by brand of grapefruit juice, Fitoterapia, 71,154,... 

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. 

The clinical relevance of data obtained from studies with single compounds is questionable, because most studies were performed in in vitro systems, limiting the predictability of the effects of the examined compounds in vivo. Moreover, some polyphenolics, such as quercetin, were shown to interact with the absorption or metabolism of drugs only at very high concentrations (50-100 pmol/L), which are likely to exceed the expected in vivo concentration after the consumption of a moderate amount of a grapefruit/ citrus product. Also, flavonoids have been demonstrated to potentially induce apoptosis in cell lines at concentrations comparable to those used for some in vitro drug interaction studies (64-66). This potentially could have impaired the investigation of enzyme and transporter activities. 

For lemon juice, the flavonoid composition was characterized by HPLC with photodiode detection at 287 nm (108), the HPLC condition based on a procedure proposed by Kirksey et al. (103) for the detection of fruit juice adulteration. Hesperidin and eriocitrin were the characteristic flavonoids of lemon juice. Flavonoid content by HPLC was used to study the effects of processing and pulp removal on flavonoid composition in lemon juice. Eriocitrin is also used in distinguishing lemon juice from grapefruit and orange juices, which do not contain this flavonoid. 

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. 

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