title: Structure-activity relationships of flavonoids as inhibitors of breast cancer resistance protein (BCRP).
abstract: Flavonoids are an interesting group of natural products ubiquitously present in human diet. Their consumption has been associated with various and differing beneficial health effects. However, several flavonoids have been reported to inhibit the breast cancer resistance protein (BCRP) encoded by the ABCG2 gene. Thus, the consumption of flavonoids with high inhibitory activity could change pharmacokinetics and drug levels of drugs that are BCRP substrates. In cancer patients receiving chemotherapy an increased intake of such flavonoids could lead to adverse effects. We investigated a structurally diverse set of flavonoids, including derivatives with a rare C-methylated structure that were isolated from plants used in traditional medicine. The flavones retusin and ayanin were found to be highly potent inhibitors of BCRP, showing only slightly less potency than Ko143, the most potent ABCG2 inhibitor known so far. The activity data were analyzed by 2D and 3D QSAR analyses and the results revealed the impact of the different substituents at the various positions of the flavonoid core on activity. Additionally, a lateral 2D QSAR analysis of data collected from the literature was performed aiming to derive more general information about the influence of distinct structural features on the inhibitory potency of flavonoids. The comparative QSAR analyses led to a consistent picture of the effects of the different substituents at various positions of the flavone backbone. The following structural features were found to contribute positively to BCRP inhibition: a hydroxyl group in position 5, double bond between position 2 and 3, and a methoxy group in position 3. The exchange of a 3-methoxy group by an OH-group acting also as a hydrogen bond donor, resulted in decrease in activity underlining the potential role of the hydrogen bond acceptor 3-OCH(3) for the interaction with BCRP.
authors.affiliation: Pharmaceutical Institute, University of Bonn, Pharmaceutical Chemistry II, An der Immenburg 4, 53121 Bonn, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Pick
authors.forename: Henrik
authors.initials: H
authors.lastname: Müller
authors.forename: Ralf
authors.initials: R
authors.lastname: Mayer
authors.forename: Britta
authors.initials: B
authors.lastname: Haenisch
authors.forename: Ilza K
authors.initials: IK
authors.lastname: Pajeva
authors.forename: Mathias
authors.initials: M
authors.lastname: Weigt
authors.forename: Heinz
authors.initials: H
authors.lastname: Bönisch
authors.forename: Christa E
authors.initials: CE
authors.lastname: Müller
authors.forename: Michael
authors.initials: M
authors.lastname: Wiese
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000737:chemistry*; D001943:Breast Neoplasms / Q000188:drug therapy; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D005260:Female; D005419:Flavonoids / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D021281:Quantitative Structure-Activity Relationship
chemical_list: C116614:ABCG2 protein, human; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D005419:Flavonoids; D009363:Neoplasm Proteins