title: Synthesis and biological evaluation of flavones and benzoflavones as inhibitors of BCRP/ABCG2.
abstract: Multidrug resistance (MDR) often leads to a failure of cancer chemotherapy. Breast Cancer Resistance Protein (BCRP/ABCG2), a member of the superfamily of ATP binding cassette proteins has been found to confer MDR in cancer cells by transporting molecules with amphiphilic character out of the cells using energy from ATP hydrolysis. Inhibiting BCRP can be a solution to overcome MDR. We synthesized a series of flavones, 7,8-benzoflavones and 5,6-benzoflavones with varying substituents at positions 3, 3' and 4' of the (benzo)flavone structure. All synthesized compounds were tested for BCRP inhibition in Hoechst 33342 and pheophorbide A accumulation assays using MDCK cells expressing BCRP. All the compounds were further screened for their P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP1) inhibitory activity by calcein AM accumulation assay to check the selectivity towards BCRP. In addition most active compounds were investigated for their cytotoxicity. It was observed that in most cases 7,8-benzoflavones are more potent in comparison to the 5,6-benzoflavones. In general it was found that presence of a 3-OCH3 substituent leads to increase in activity in comparison to presence of OH or no substitution at position 3. Also, it was found that presence of 3',4'-OCH3 on phenyl ring lead to increase in activity as compared to other substituents. Compound 24, a 7,8-benzoflavone derivative was found to be most potent being 50 times selective for BCRP and showing very low cytotoxicity at higher concentrations.
authors.affiliation: Pharmaceutical Institute, University of Bonn, Pharmaceutical Chemistry II, An der Immenburg 4, 53121 Bonn, Germany.
authors.forename: Kapil
authors.initials: K
authors.lastname: Juvale
authors.forename: Katja
authors.initials: K
authors.lastname: Stefan
authors.forename: Michael
authors.initials: M
authors.lastname: Wiese
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001571:Benzoflavones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002478:Cells, Cultured; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D047309:Flavones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D015394:Molecular Structure; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D001571:Benzoflavones; D047309:Flavones; D009363:Neoplasm Proteins
keywords: Benzoflavones; Breast cancer resistance protein (BCRP); Flavonoids; MRP1; Multidrug resistance (MDR); P-gp