Table 1. Agonist EC₅₀ (nM) Pharmacology of the Modified Peptides at the Mouse Melanocortin Receptors^a.

	mMC1R		mMC3R		mMC4R		mMC5R		selectivity ratio
peptide	EC50 (nM)	fold change	EC50 (nM)	fold change	EC50 (nM)	fold change	EC50 (nM)	fold change	MC4R vs MC3R
NDP-MSH	0.018 ± 0.003		0.14 ± 0.03		0.20 ± 0.03		0.30 ± 0.05		1
AMW3-130b	0.35 ± 0.17		2.00 ± 0.45		0.27 ± 0.09		2.32 ± 0.57		7
heterocycle	164 ± 22		7600 ± 1890		650 ± 126		335 ± 106		12
AMW610c	33 ± 9	1	495 ± 215	1	85 ± 13	1	72 ± 16	1	9
AST3-88	68.8 ± 17.9	2	255 ± 24	(2)	4.7 ± 0.49	(18)	11.9 ± 2.3	(6)	54
AMW6103	0.81 ± 0.25	(41)	5300 ± 4300	11	440 ± 220	5	31.0 ± 16.2	(2)	12

^aThe indicated errors represent the standard error of the mean determined from at least three independent experiments. Parentheses indicate that an increase in potency has resulted. Changes less than 3-fold are considered to be within the inherent experimental assay error.

^bThe AGRP-melanocortin chimeric peptide AMW3-130 has been previously reported in ref (34) as compound 1.

^cThe AMW610 compound has been previously reported in ref (34) as compound 7.