3-Methoxylphenylpropyl amides as novel receptor subtype-selective melatoninergic ligands: characterization of physicochemical and pharmacokinetic properties

Mapping the Melatonin Receptor. 8. Selective MT2 Agonists derived from 5,6-dihydroindolo[2,1-a]isoquinolines and related systems

A series of substituted indolo[2,1- a ]isoquinolines and indolo[1,2- a ]benzoxazines have been prepared, as melatonin analogues, to investigate the nature of the binding site of the melatonin receptor. Agonist and antagonist potency of all the analogues was measured using the [35S]GTPγS binding assay protocol. The binding affinity of the analogues were measured by competition binding studies against the human MT1 (hMT1) and MT2 (hMT2) receptors stably transfected in Chinese Hamster Ovarian (CHO) cells, using 2-[ 125 I]-iodomelatonin, as a ligand.  N -Acetyl 2-(10-methoxy-5,6-dihydroindolo[2,1- a ]isoquinolin-12-yl)propyl-1-amine  (12a)  binds strongly to both the hMT1 and hMT2 receptors, and shows a preference for the hMT2, as does Its propanamido counterpart  12b . The introduction of two methyl groups into their side chain, analogues  15a  and 1 5b,  leads to antagonism, in the case of the former, and drastically diminishes its hMT1 binding; an analogous profile is seen for  15b , which, however, is a partial agonist.. Introduction of chlorine or methoxyl groups into ring 4 gives compounds, that are weakly binding, with a preference for MT2. Substitution of oxygen for carbon at position 5 gives the indolo[1,2- c ]benzoxazines  33 ,  36a  and  b , that bind strongly to the human receptors,  33 ,  36b  are potent agonists at the melatonin receptors, but do not discriminate between hMT1 and hMT2.

Discovery of : A Novel Potent and Peripherally Preferred Melatonin Receptor Agonist that Reduces Liver Triglycerides and Steatosis in Diet-Induced Obese Rats

The modulation of melatonin signaling in peripheral tissues holds promise for treating metabolic diseases like obesity, diabetes, and nonalcoholic steatohepatitis. Here, several benzimidazole derivatives have been identified as novel agonists of the melatonin receptors MT1 and MT2. The lead compounds 10b, 15a, and 19a demonstrated subnanomolar potency at MT1/MT2 receptors, high oral bioavailability in rodents, peripherally preferred exposure, and excellent selectivity in a broad panel of targets. Two-month oral administration of 10b in high-fat diet rats led to a reduction in body weight gain similar to dapagliflozin with superior results on hepatic steatosis and triglyceride levels. An early toxicological assessment indicated that 10b (also codified as ACH-000143) was devoid of hERG binding, genotoxicity, and behavioral alterations at doses up to 100 mg/kg p.o., supporting further investigation of this compound as a drug candidate.

Fluorine substituted methoxyphenylalkyl amides as potent melatonin receptor agonists

A series of fluorine substituted methoxyphenylalkyl amides were prepared with different orientations of the fluorine and methoxy groups with respect to the alkylamide side chain and with alkyl sides of differing lengths (n = 1-3). β-Dimethyl and α-methyl derivatives were also synthesised. The compounds were tested as melatonin agonists and antagonists using the pigment aggregation of Xenopus melanophores as the biological assay. A number of these compounds were potent melatonin agonists, the potency depending on the length of the alkyl chain, the orientation of the methoxy and fluorine substituents, the amide chain length and, for the ethyl side-chain analogues, the presence of β-substituents.