title: Flavonoid binding to human serum albumin.
abstract: Dietary flavonoid may have beneficial effects in the prevention of chronic diseases. However, flavonoid bioavailability is often poor probably due to their interaction with plasma proteins. Here, the affinity of daidzein and daidzein metabolites as well as of genistein, naringenin, and quercetin for human serum albumin (HSA) has been assessed in the absence and presence of oleate. Values of the dissociation equilibrium constant (K) for binding of flavonoids and related metabolites to Sudlow's site I range between 3.3x10(-6) and 3.9x10(-5)M, at pH 7.0 and 20.0 degrees C, indicating that these flavonoids are mainly bound to HSA in vivo. Values of K increase (i.e., the flavonoid affinity decreases) in the presence of saturating amounts of oleate by about two folds. Present data indicate a novel role of fatty acids as allosteric inhibitors of flavonoid bioavailability, and appear to be relevant in rationalizing the interference between dietary compounds, food supplements, and drugs.
authors.affiliation: Department of Biology, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bolli
authors.forename: Maria
authors.initials: M
authors.lastname: Marino
authors.forename: Gerald
authors.initials: G
authors.lastname: Rimbach
authors.forename: Gabriella
authors.initials: G
authors.lastname: Fanali
authors.forename: Mauro
authors.initials: M
authors.lastname: Fasano
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
mesh_terms: D001682:Biological Availability; D004032:Diet; D044950:Flavanones / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000493:pharmacokinetics; D005419:Flavonoids / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000493:pharmacokinetics*; D019833:Genistein / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D007529:Isoflavones / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000493:pharmacokinetics; D019301:Oleic Acid / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D011794:Quercetin / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000493:pharmacokinetics; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D044950:Flavanones; D005419:Flavonoids; D007529:Isoflavones; D012709:Serum Albumin; D019301:Oleic Acid; C004742:daidzein; D011794:Quercetin; D019833:Genistein; C005273:naringenin