Potent and selective peptide agonists of alpha-melanotropin action at human melanocortin receptor 4: their synthesis and biological evaluation in vitro.
alpha-Melanotropin (alphaMSH) and several of its derivatives are potent but not selective agonists at melanocortin receptors 3, 4, and 5 present in the brain (MC3-5R). To differentiate between the physiological role of hMC-4R (believed to be involved in regulation of energy balance) from those of melanocortin receptors 3 and 5, potent and receptor-specific agonists are needed. Therefore, the cyclic derivatives of alphaMSH of a general structure, cyclo(X-His-d-Phe-Arg-Trp-Y)-NH(2), where X is succinic acid or an omega-amino-carboxylic acid, and Y is an alpha,omega-di-amino-carboxylic acid or an omega-carboxy-alpha-amino acid, were prepared and tested in binding assays and in cAMP assays on CHO cells expressing hMC3-5R. Several of the 21-membered or larger lactams turned out to be potent and hMC-4R-selective agonists. For instance, cyclo(CO-CH(2)-CH(2)-CO-His-d-Phe-Arg-Trp-Dab)-NH(2) (Dab: 2,4-di-amino-butyric acid) was a potent agonist at hMC-4R (EC(50) = 4 nM) with 55-fold selectivity over hMC-3R and greater than 1000-fold selectivity over hMC-5R. Another potent and selective compound was cyclo(NH-CH(2)-CH(2)-CO-His-d-Phe-Arg-Trp-Glu)-NH(2): EC(50) about 1 nM at hMC-4R, with 90-fold selectivity over hMC-3R and greater than 2000-fold selectivity over hMC-5R.
Bednarek
M A
MA
Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, New Jersey 07065, USA. maria_bednarek@merck.com
MacNeil
T
T
Tang
R
R
Kalyani
R N
RN
Van der Ploeg
L H
LH
Weinberg
D H
DH
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis; D004353:Drug Evaluation, Preclinical; D006801:Humans; D020128:Inhibitory Concentration 50; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000494:pharmacology; D044104:Receptor, Melanocortin, Type 3; D044105:Receptor, Melanocortin, Type 4; D018043:Receptors, Corticotropin / Q000378:metabolism; D044101:Receptors, Melanocortin; D018000:Receptors, Peptide / Q000378:metabolism*; D000521:alpha-MSH / Q000819:agonists*
D010455:Peptides; D010456:Peptides, Cyclic; D044104:Receptor, Melanocortin, Type 3; D044105:Receptor, Melanocortin, Type 4; D018043:Receptors, Corticotropin; D044101:Receptors, Melanocortin; D018000:Receptors, Peptide; C581396:cyclo(NH-CH(2)-CH(2)-CO-His-D-Phe-Arg-Trp-Glu)-NH(2); C086971:melanocortin 5 receptor; D000521:alpha-MSH; D000242:Cyclic AMP