GLP is released in response to ingestion

GLP-1 is released in response to ingestion of nutrients including carbohydrates, protein, and fat. Recent studies aimed at identifying the receptors involved in nutrient stimulated GLP-1 secretion have identified free fatty perindopril erbumine sale receptor 4 (FFA4/GPR120) as a potential 7TM receptor involved in long-chain fatty acid stimulated GLP-1 secretion. FFA4 is highly expressed in the intestine and the intestinal endocrine cell line STC-1, additionally FFA4 mRNA has been detected in murine L-cells. Elucidating the mechanism of FFA4 mediated GLP-1 secretion would be greatly aided by the identification of selective small molecule agonists and antagonists. With this goal in mind, efforts directed toward the identification of small molecule FFA4 modulators culminating in a series of diarylsulfonamide agonists are described herein. Compound was identified as a starting point for optimization following a FLIPR based medium throughput screening campaign conducted in a HEK293 cell line expressing human FFA4 (see ). The potency and efficacy of compound was determined using a ten-point response curve in mammalian U2OS cells expressing human FFA4 with a FLIPR readout run in both agonist and antagonist modes. The ease of synthesis of diarylsulfonamides combined with the plethora of commercially available starting materials made compound an attractive starting point for SAR development. The general synthesis of the diarylsulfonamide agonists is shown in . Sulfonamide bond formation was typically formed by reaction of the aniline and arylsulfonyl chloride in pyridine at room temperature. In cases where electron-deficient anilines were employed, heating to elevated temperatures was required. Our initial studies explored substitution about the aniline ring of the diarylsulfonamides (). Whereas monoakyl-substitution on the aniline ring resulted in compounds devoid of activity (–), dialkyl-substitution (–) provided activity equivalent to hit compound . Larger alkyl groups at positions 2 and 6 of the aniline ring were not tolerated (), however addition of an alkyl group at the 4-position, to provide 2,4,6-trimethyl analog provided a substantial increase in potency. N-substitution (–) was not tolerated. With our initial survey of the aniline SAR completed, we turned our attention toward exploration of the substitution on the arylsufonyl group (). Varying the position of a methoxy substituent revealed that -substitution () was not tolerated while -substitution () provided the most potent agonists. With this information in hand, we concentrated on -substitution and identified that small nonpolar substituents were preferred, with the 4-methoxy substituent () providing the best balance of potency and efficacy. Interestingly, substitution with an electron withdrawing trifluoromethoxy group () provided nearly equal potency yet reduced efficacy (53% max response). Disubstitution at the 3- and 4-postions was well tolerated, with 5-membered fused rings ( vs ) providing optimal activity. Finally we explored the SAR at the 4-position of the aniline (). Incremental increases in the length of the alkyl group () maintained FFA4 activity, while further increases in the steric bulk of the alkyl group eroded activity (). Consistent with the previous SAR small lipophilic groups were tolerated (–), however, attempts to introduce more polar functionality at the 4-position (–) were not successful. Having completed our SAR studies around the diarylsulfonamide template, we chose agonist , GSK137647A, for further in vitro selectivity profiling (). Compound was evaluated against a panel of 65 targets in both full curve functional and binding assays and was shown to provide at least 100-fold selectivity against the panel which included 41 G-protein-coupled receptors (GPCRs), including additional members of the free fatty acid receptors (FFA1, FFA2, and FFA3). Profiling against the rodent ortholog receptors showed compound maintained activity against the mouse and rat FFA4 receptors while maintaining selectivity over the rodent FFA1, FFA2, and FFA3 receptors. While the selectivity of compound is promising, the poor solubility of the compound measured in simulated intestinal fluid (FASSIF) greatly limited the utility of the compound for in vivo experiments.