Structure-based design of dipeptide derivatives for the human neutral endopeptidase

Discovery of Novel Multi-target Inhibitor of angiotensin type 1 receptor and neprilysin inhibitors from Traditional Chinese Medicine

Angiotensin II type-1 receptor–neprilysin inhibitor (ARNi) is consisted of Angiotensin II type-1 receptor (AT1) antagonist and neprilysin (NEP) inhibitor, which could simultaneously increase the vasodilators of the natriuretic peptides and antagonize vasoconstrictors of Ang II. ARNi has been proved a superior effect and lower risks of death on chronic heart failure (CHF) and hypertension. In this paper, ARNi from Traditional Chinese Medicines (TCM) was discovered based on target combination of AT1 and NEP by virtual screening, biological assay and molecular dynamics (MD) simulations. Two customized strategies of combinatorial virtual screening were implemented to discover AT1 antagonist and NEP inhibitor based on pharmacophore modeling and docking computation respectively. Gyrophoric acid (PubChem CID: 135728) from Parmelia saxatilis was selected as AT1 antagonist and assayed with IC₅₀ of 29.76 μM by calcium influx assay. And 3,5,3′-triiodothyronine (PubChem CID: 861) from Bos taurus domesticus was screened as NEP inhibitor and has a dose dependent inhibitory activity by biochemistry fluorescence assay. Combined with MD simulations, these compounds can generate interaction with the target, key interactive residues of ARG167, TRP84, and VAL108 in AT1, and HIS711 in NEP were also identified respectively. This study designs the combinatorial strategy to discover novel frames of ARNi from TCM, and gyrophoric acid and 3,5,3′-triiodothyronine could provide the clues and revelations of drug design and therapeutic method of CHF and hypertension for TCM clinical applications.

Alanine scan of sialorphin and its hybrids with opiorphin: synthesis, molecular modelling and effect on enkephalins degradation

Enkephalins are involved in a number of physiological processes. However, these peptides are quickly degraded by peptidases, e.g. the neutral endopeptidase (NEP). Inhibition of the enzymatic degradation of enkephalins is one of the possible approaches to prolong their activity. Selective inhibitor of NEP, sialorphin, is the attractive lead compound for enkephalins degradation studies. In this work, an alanine scan of sialorphin and a series of its hybrids with opiorphin, synthesised by the solid phase method, were performed. The effect of the peptides on degradation of Met-enkephalin by NEP in vitro was investigated. Molecular modelling technique was used to identify residues responsible for protein–ligand interactions. We showed that substitution of amino acids Gln¹, Pro⁴ and Arg⁵ of sialorphin for Ala significantly reduced the half-life of Met-enkephalin in the presence of NEP. [Ala³]sialorphin displayed a higher inhibitory potency against NEP than sialorphin. Substitution of His² for Ala led to a compound which was as active as lead compound. Sialorphin has a structure which hardly tolerates substitution in its sequence at positions 1, 4 and 5. The conversion of His² for alanine in sialorphin is tolerated very well. The higher inhibitory potency of [Ala³]sialorphin than sialorphin against NEP is caused by removal of the hydrophilic residue (Asn) and a better fit of the peptide to the enzyme-binding pocket. The role of side chains of sialorphin in degradation of enkephalin by NEP has been explored. This study also provides an important SAR information essential for further drug design.