Constraining the Side Chain of C-Terminal Amino Acids in Apelin-13 Greatly Increases Affinity, Modulates Signaling, and Improves the Pharmacokinetic Profile

Abstract

Side-chain-constrained amino acids are useful tools to modulate the biological properties of peptides. In this study, we applied side-chain constraints to apelin-13 (Ape13) by substituting the Pro12 and Phe13 positions, affecting the binding affinity and signaling profile on the apelin receptor (APJ). The residues 1Nal, Trp, and Aia were found to be beneficial substitutions for Pro12, and the resulting analogues displayed high affinity for APJ (K i 0.08–0.18 nM vs Ape13 K i 0.7 nM). Besides, constrained (d-Tic) or α,α-disubstituted residues (Dbzg; d-α-Me-Tyr­(OBn)) were favorable for the Phe13 position. Compounds 47 (Pro12-Phe13 replaced by Aia-Phe, K i 0.08 nM) and 53 (Pro12-Phe13 replaced by 1Nal–Dbzg, K i 0.08 nM) are the most potent Ape13 analogues activating the Gα12 pathways (53, EC50 Gα12 2.8 nM vs Ape13, EC50 43 nM) known to date, displaying high affinity, resistance to ACE2 cleavage as well as improved pharmacokinetics in vitro (t 1/2 5.8–7.3 h in rat plasma) and in vivo.

Apelin and Vasopressin: The Yin and Yang of Water Balance

“…The short half-life of apelin in vivo has encouraged the development of metabolically stable apelin analogs for potential therapeutic applications. Numerous approaches ( Table 1 ), such as PEGylation ( 107 – 109 , 112 , 113 ), synthetic modifications to the RPRL motif of apelin ( 18 ), palmitoylation and the use of unnatural amino acids ( 38 , 103 , 107 , 114 , 115 ), or main-chain modifications (cyclization) ( 106 , 116 , 117 ), have now been used to increase the half-life of apelin peptides. Recent studies have reported the development of nonpeptidic ApelinR agonists that mimic the signaling properties of apelin, some of them are orally active ( Table 1 ) ( 104 , 110 , 111 ).…”

“…Most studies aiming to develop apelin analogs have focused on pE13F ( 38 , 103 , 105 , 106 , 115 – 117 ) and apelin-36 ( 108 , 109 , 112 ) ( Table 1 ). However, K17F, which has an affinity 10 times higher than that of pE13F for human ApelinR, induces β-arrestin recruitment and the internalization of the rat ApelinR 10 to 30 times more strongly than pE13F, and also decreases arterial BP more effectively ( 29 , 38 ).…”

Éric Marsault (1971–2021): A Legacy through the Prism of Relationship Chemistry

“…His group reported the most potent agonists (<10 pM) of the apelin G protein-coupled receptor (APJ) as well as very potent and selective neurotensin receptor agonists (NTS1, NTS2). This work provided highly biased compounds essential to our understanding of how ligand structure influences receptor dynamics and how this signaling bias affects pathophysiology. − …”

“…Comparison of NT(8–13) to its macrocyclic analogue inside the orthosteric binding pocket of the human neurotensin 1 receptor (NTS1). (A) 3D structure of the NTS1 orthosteric site with blue arrows spanning the free space between Tyr and Arg . (B) Superimposed structures of NT(8–13) and its macrocyclic analogue (docked).…”

Size-Reduced Macrocyclic Analogues of [Pyr1]-apelin-13 Showing Negative Gα12 Bias Still Produce Prolonged Cardiac Effects

“…29 The cyclopentyl group (Cyp) was found to affect the binding and signaling profile of Tyr(OBn)-containing peptides in our previous study. 67 It was introduced on tyrosine (13) using 2 equivalents of cyclopentanol in 85% phosphoric acid under reflux conditions to form the precursor 14 (Scheme 4). This intermediate followed a series of transformations (esterification of 14, Boc protection of 15, alkylation of 16, ester hydrolysis of 17, Boc removal of 18, and Fmoc protection) to provide Fmoc-cypTyr(OBn)-OH (19a), Fmoc-cypTyr(OCyp)-OH (19b), and Fmoc-cypTyr(OPr)-OH (19c), which are suitable for SPPS.…”