Structure–Activity Relationship Studies of the Natural Product G_q/11 Protein Inhibitor YM‐254890

Abstract

G proteins act as molecular switches in G protein‐coupled receptor signaling pathways and are key mediators for numerous important physiological processes. The natural product, cyclic depsipeptide YM‐254890, together with the structurally similar FR900359, is the only known selective inhibitor of the Gq/11 subfamily of G proteins. We recently reported the first total synthesis of YM‐254890 and FR900359, followed by synthesizing analogues to perform structure–activity relationship studies. However, incomplete information about their structure–activity relationship prevents the further development of potent and structurally simplified analogues. Herein we report the first systematic structure–activity relationship study toward the N‐methyldehydroalanine moiety in YM‐254890, by designing and synthesizing seven new analogues. Pharmacological characterization of the seven compounds for Gq/11‐, Gi/o‐ and Gs‐mediated signaling showed that the simplified analogue YM‐19 is the most potent Gq/11inhibitor among the new analogues. This study provides information for the future design of potent and simplified YM‐254890 analogues.

Recent achievements in developing selective Gq inhibitors

“…The inhibitory effect on G q ‐, G s ‐ and G i ‐mediated signaling of YM‐254890 and analogs has been characterized by inositol monophosphate (IP 1 ) assay of the M 1 muscarinic receptor in Chinese hamster ovary (CHO) (G q signaling), isoproterenol‐induced cAMP assay of the β 2 ‐adrenergic receptor in human embryonic kidney (HEK) 293 cells (G s signaling), and cAMP assay of the rat metabotropic glutamate receptor 2 (mGlu 2 receptor) in CHO cells (G i signaling). Here it was shown that YM‐254890 is a potent, selective inhibitor of G q ‐mediated signaling (Figure A), verifying the important pharmacological role of N ‐MeDha residue in YM‐254890 for strong inhibition of G q ‐mediated signaling, as analogs 9 to 15 , which replaced the N ‐MeDha residue with residues with d ‐stereochemistry and variations in the side chains, and the hydrogenated analogs, analogs 7 and 8 also generated by hydrogenation of N ‐MeDha in the natural product to epimeric N ‐Me‐ l ‐Ala and N ‐Me‐ d ‐Ala, respectively, are all less potent than YM‐254890 (Figure ). It was also outlined that the structural integrity of YM‐254890 is critical for possessing potent G q inhibition activity, as even small structural changes can result in substantial differences in pharmacological activity, however, modification at certain sites were allowed and did not compromise potency (Figures a and ).…”

“…Analog 57 was generated by hydrogenation of the N ‐MeDha in FR900359 to a mixture of N ‐Me‐ l ‐Ala and N ‐Me‐ d ‐Ala, and slightly less potent than FR900359 (Figure ), indicating the α,β‐unsaturated exomethylene group within FR900359 is not crucial for Gα q/11 inhibition. However, prior published data suggest that the unsaturated exomethylene group in YM‐254890 plays an important role in the inhibition of G q ‐mediated signaling (Figure ) . This conflicting result may have been a result of the different cell‐assays conditions or from using the two slightly different structural templates.…”

“…b, Inhibition of the adenosine diphosphate (ADP)‐induced platelet aggregation in human platelet‐rich plasma . c, d, and e, Inhibition of carbachol‐induced inositol monophosphate (IP 1 ) production in Chinese hamster ovary (CHO) cells that stably express the M 1 muscarinic receptor in different papers: (c) from Xiong et al, (d) from Zhang et al and Xiong et al, and (e) from Reher et al Equipotent analogs are highlighted (pink). The chemical structures were determined by mass spectrometry, one‐ and two‐dimensional nuclear magnetic resonance (NMR) spectrum analysis, chiral high‐performance liquid chromatography (HPLC), Marfey's analysis, high‐resolution mass spectroscopy (HRMS), infrared spectroscopy (IR), and optical rotation.…”

“…d, Inhibition of the adenosine diphosphate (ADP)‐induced platelet aggregation in vitro . e, f, g, h, i, and j, Inhibition of carbachol‐induced IP 1 production in Chinese hamster ovary (CHO) cells that stably express the M 1 muscarinic receptor in different papers: (e) from Xiong et al, (f) from Xiong et al, (g) from Zhang et al, (h) from Zhang et al, (i) from Reher et al, and (j) from Zhang…”

“…Subsequently, the versatility of the synthetic methodology was demonstrated by the synthesis of more than 30 structurally and stereochemically diverse analogs, which allowed for systematic structure‐activity relationship (SAR) studies of YM‐254890 that focus on the modification of key structural elements such as (i) the N ‐MeDha residue (YM‐385780 ( 7 ), YM‐385781 ( 8 ), YM‐19 to YM‐25 ( 9 ‐ 15 ), Figure ), (ii) the backbone (YM‐1 to YM‐5 ( 16 ‐ 20 ), Figure ), (iii) key β‐HyLeu moieties (YM‐6 to YM‐9 ( 21 ‐ 24 ), YM‐10 ( 2 , also known as YM‐254891), Figures a and ), (iv) side‐chains of N ‐MeAla and Ala (YM‐11 to YM‐18 ( 25‐32 ), Figure ), and (v) side chains of Thr and the N ‐acyl group of β‐HyLeu‐1 (YM‐26 to YM‐30 ( 33 ‐ 37 ), Figure ) . These analogs have highlighted how the bulkiness, stereochemistry and electron density of each amino acid in YM‐254890 influence G q inhibitory potency and selectivity.…”