title: Design and Synthesis of Irreversible Analogues of Bardoxolone Methyl for the Identification of Pharmacologically Relevant Targets and Interaction Sites.
abstract: Semisynthetic triterpenoids such as bardoxolone methyl (methyl-2-cyano 3,12-dioxooleano-1,9-dien-28-oate; CDDO-Me) (4) are potent inducers of antioxidant and anti-inflammatory signaling pathways, including those regulated by the transcription factor Nrf2. However, the reversible nature of the interaction between triterpenoids and thiols has hindered attempts to identify pharmacologically relevant targets and characterize the sites of interaction. Here, we report a shortened synthesis and SAR profiling of 4, enabling the design of analogues that react irreversibly with model thiols, as well as the model protein glutathione S-transferase P1, in vitro. We show that one of these analogues, CDDO-epoxide (13), is comparable to 4 in terms of cytotoxicity and potency toward Nrf2 in rat hepatoma cells and stably modifies specific cysteine residues (namely, Cys-257, -273, -288, -434, -489, and -613) within Keap1, the major repressor of Nrf2, both in vitro and in living cells. Supported by molecular modeling, these data demonstrate the value of 13 for identifying site(s) of interaction with pharmacologically relevant targets and informing the continuing development of triterpenoids as novel drug candidates.
authors.affiliation: Department of Chemistry, University of Liverpool , L69 7ZD Liverpool, U.K.|MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Michael H L
authors.initials: MH
authors.lastname: Wong
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Holly K
authors.initials: HK
authors.lastname: Bryan
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Copple
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Rosalind E
authors.initials: RE
authors.lastname: Jenkins
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Pak Him
authors.initials: PH
authors.lastname: Chiu
authors.affiliation: Department of Chemistry, University of Liverpool , L69 7ZD Liverpool, U.K.
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Bibby
authors.affiliation: Department of Chemistry, University of Liverpool , L69 7ZD Liverpool, U.K.
authors.forename: Neil G
authors.initials: NG
authors.lastname: Berry
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Kitteringham
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Goldring
authors.affiliation: Department of Chemistry, University of Liverpool , L69 7ZD Liverpool, U.K.
authors.forename: Paul M
authors.initials: PM
authors.lastname: O'Neill
authors.affiliation: MRC Centre for Drug Safety Science, Department of Molecular and Clinical Pharmacology, University of Liverpool , L69 3GE Liverpool, U.K.
authors.forename: B Kevin
authors.initials: BK
authors.lastname: Park
mesh_terms: D000818:Animals; D006801:Humans; D051379:Mice; D051381:Rats; D048868:Adaptor Proteins, Signal Transducing / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000378:metabolism; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000138:chemical synthesis / Q000494:pharmacology; D000975:Antioxidants / Q000138:chemical synthesis / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003598:Cytoskeletal Proteins / Q000187:drug effects; D015195:Drug Design; D051549:Glutathione S-Transferase pi / Q000187:drug effects; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors; D057166:High-Throughput Screening Assays; D000072019:Kelch-Like ECH-Associated Protein 1; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy; D008958:Models, Molecular; D009828:Oleanolic Acid / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000494:pharmacology; D014315:Triterpenes / Q000737:chemistry / Q000494:pharmacology; D051267:NF-E2-Related Factor 2
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000255:Adenosine Triphosphate; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; C445068:bardoxolone methyl; D003598:Cytoskeletal Proteins; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; C496556:GSTP1 protein, human; C117301:Keap1 protein, mouse; D000072019:Kelch-Like ECH-Associated Protein 1; D009828:Oleanolic Acid; D014315:Triterpenes; D051267:NF-E2-Related Factor 2