Flavonoids conjugation

We have designed not only polymerized flavonoids but also flavonoid conjugates of various polyamines, in consideration of extension of the amplification of physiological properties of the flavonoids. Polymeric flavonoids were synthesized by the enzymatic oxidative coupling. ... 

Flavonoids conjugate addition and heterocyclic ring formation... 

Williamson G, Barron D, Shimoi K, Terao J. 2005. In vitro biological properties of flavonoid conjugates found in vivo. Free Radic Res 39 457 459. 

The Small Intestine Is the Major Site of Flavonoid Conjugation.25... 

Flavonoid conjugates, aromatic carboxylic acids, alkaloids, phenylpropanoids Tomato peel and flesh LC-PDA-TOF MS 83... 

Ibrahim, R. K., Immunolocalization of flavonoid conjugates and their enzymes in Phenolic Metabolism in Plants (H. A. Stafford and R. K. Ibrahim, eds.), Recent Advances in Phytochemistry Vol. 26, 25-61, Plenum Press, New York, 1992. 

Figure 2 Potential interactions of bioavailable flavonoid conjugates with the blood brain barrier (BBB).

The extent to which the findings with QG and genistin apply to oflier flavonoid glucosides or flavonoids conjugated with other sugar moieties is not yet known. Further experiments in this area may benefit from using the Caco-2 cell as a model. 

Intestinal excretion is an important mechanism in the elimination of flavonoid conjugates [82-84]. This is likely mediated by the multidrug resistance-associated protein (MRP) pumps. MRPs actively export conjugated metabolites out of the small intestine back into the intestinal lumen and so prevent or reduce systemic circulation [85]. An experiment using cultured Caco-2 cells showed that two metabolites of epicatechin were excreted on the apical side of the cells. Their elimination has been attributed to MRP-2, as efflux was significantly reduced by a competitive MRP-2 inhibitor [86]. Conversely, intestinal perfusion experiments with catechin indicate that catechin metabolites are not substrates for these transport proteins [49]. 

Abranko L, Garcia-Reyes JF, MoMna-Diaz A (2001) In-source fragmentation and accurate mass analysis of multiclass flavonoid conjugates by electrospray ionization time-of-flight mass spectrometry. J Mass Spectrom 46(5) 478-488. doi 10.1002/jms.l914... 

Approaches to the identification of flavonoid conjugates in plasma and urine... 

A summary of the data in the various reports concerned with the structures of flavonoid conjugates in vivo has been published recently (Kroon et al. 2004) therefore, only a brief summary will be provided here, and the reader is advised to refer to this citation for a more detailed account. As mentioned, more detailed investigations are emerging as technology permits (Mullen etal. 2004,2006 Jaganath etal. 2006). 

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