252008-71-2Relevant academic research and scientific papers
PHARMACOLOGICAL CHAPERONES FOR TREATING OBESITY
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Page/Page column 2/18; 3/18, (2008/06/13)
The invention relates to methods of enhancing normal melanocortin-4 receptor (MC4R) activity, and to enhancing activity of an MC4R having a mutation which affects protein folding and/or processing of the MC4R. The invention provides a method of treating an individual having a condition in which increased activity of an MC4R at the cell surface would be beneficial, for example in obesity, by administering an effective amount of a pharmacological chaperone for the MC4R. The invention provides MC4R pharmacological chaperones which enhance the activity of MC4R. The invention further provides a method of screening to identify pharmacological chaperones which enhance folding of an MC4R in the endoplasmic reticulum (ER), in order to enhance the activity of the MC4R at the cell surface.
New substituted piperazines as ligands for melanocortin receptors. Correlation to the X-ray structure of "THIQ"
Mutulis, Felikss,Yahorava, Sviatlana,Mutule, Ilze,Yahorau, Aleh,Liepinsh, Edvards,Kopantshuk, Sergei,Veiksina, Santa,Tars, Kaspars,Belyakov, Sergey,Mishnev, Anatoly,Rinken, Ago,Wikberg, Jarl E. S.
, p. 4613 - 4626 (2007/10/03)
A series of piperazine analogues of the melanocortin 4 receptor (MC4R) specific small-molecule agonist "THIQ" was synthesized and characterized structurally and pharmacologically. First, several THIQ imitations lacking the triazole moiety were prepared. Syntheses included acylation of 4-phenylpiperazine or 4-cyclohexylpiperazine. In two cases the tertiary amine function was replaced by the corresponding N-oxide. To obtain more complex structures, a 4-substituted piperazine ring was formed by alkylation of the primary amino group of cyclohexane-derived amino alcohols with N,N-bis(2-chloroethyl)benzylamine. The hydroxylic group of the intermediate was first activated with methanesulfonyl chloride, and the sulfonic ester formed in situ was introduced into the reaction with the sodium salt of 1,2,4-triazole. In one case (i.e., preparation of 23c) introduction of the 1,2,4-triazole moiety was performed at a carbon of the cyclohexane ring. In addition, this intermediate contained a piperazine moiety connected via its nitrogen atom to a cyclohexane ring carbon neighboring the reaction center. As established in NMR and X-ray investigations herein, this substitution proceeded with retention of the initial trans configuration of 1,2-disubstituted cyclohexane. To obtain pure enantiomers of 23c, its precursor 21c was subjected to chiral chromatography on a Chirobiotic V column. The derivatives (R,R)-21cand (S,S)-21c obtained were introduced into further syntheses steps, giving (R,R)-23c and (S,S)-23c, respectively. Melanocortin MC1,3-5 receptor binding studies showed that all tested piperazine derivatives were active. Several compounds showed clear selectivity for MC4R, with submicromolar affinities being obtained. Among them, one substance, (R,R)-23c, displayed a biphasic curve in displacement of [125I]NDP-MSH on MC4R [K(i)high = 1 nM and K(i)low = 260 nM]. This biphasic competition curve was similarly biphasic to the competition curve obtained herein using THIQ. An X-ray study performed on crystals of the THIQ sulfate salt revealed two closely related conformations, which resemble the shape of the letter "Y", where piperidine and 4-chlorophenyl groups are situated close to each other, but the 1,2,3,4-tetrahydroisoquinoline residue is remote, the triazole function being highly exposed to the environment. The crystals of the dinitrate salt of (R,R)-23c showed a different conformation, where parts of the molecule are spread out almost symmetrically around the central section. Molecular modeling, based on the THIQ crystal structure and the functional similarity of THIQ and (R,R)-23c, allowed us to suggest a possible "bioactive" conformation of (R,R)-23c that is similar to the crystal conformation of THIQ.
Synthesis and Structure-Activity Relationships of Novel Arylpiperazines as Potent and Selective Agonists of the Melanocortin Subtype-4 Receptor
Richardson, Timothy I.,Ornstein, Paul L.,Briner, Karin,Fisher, Matthew J.,Backer, Ryan T.,Biggers, C. Kelly,Clay, Michael P.,Emmerson, Paul J.,Hertel, Larry W.,Hsiung, Hansen M.,Husain, Saba,Kahl, Steven D.,Lee, Jonathan A.,Lindstrom, Terry D.,Martinelli, Michael J.,Mayer, John P.,Mullaney, Jeffery T.,O'Brien, Thomas P.,Pawlak, Joseph M.,Revell, Kevin D.,Shah, Jikesh,Zgombick, John M.,Herr, R. Jason,Melekhov, Alex,Sampson, Peter B.,King, Chi-Hsin R.
, p. 744 - 755 (2007/10/03)
The melanocortin receptors have been implicated as potential targets for a number of important therapeutic indications, including inflammation, sexual dysfunction, and obesity. We identified compound 1, an arylpiperazine attached to the dipeptide H-D-Tic-D-p-Cl-Phe-OH, as a novel melanocortin subtype-4 receptor (MC4R) agonist through iterative directed screening of nonpeptidyl G-protein-coupled receptor biased libraries. Structure-activity relationship (SAR) studies demonstrated that substitutions at the ortho position of the aryl ring improved binding and functional potency. For example, the o-isopropyl-substituted compound 29 (Ki = 720 nM) possessed 9-fold better binding affinity compared to the unsubstituted aryl ring (Ki = 6600 nM). Sulfonamide 39 (Ki = 220 nM) fills this space with a polar substituent, resulting in a further 2-fold improvement in binding affinity. The most potent compounds such as the diethylamine 44 (Ki = 60 nM) contain a basic group at this position. Basic heterocycles such as the imidazole 50 (Ki = 110 nM) were similarly effective. We also demonstrated good oral bioavailability for sulfonamide 39.
