A general approach for the synthesis of 5-substituted-4-amino-pyrrolidin-2-ones and 5-substituted-4-amino-3-pyrrolin-2-ones

Statine-based peptidomimetic compounds as inhibitors for SARS-CoV-2 main protease (SARS-CoV‑2 Mpro)

COVID-19 is a multisystemic disease caused by the SARS-CoV-2 airborne virus, a member of the Coronaviridae family. It has a positive sense single-stranded RNA genome and encodes two non-structural proteins through viral cysteine-proteases processing. Blocking this step is crucial to control virus replication. In this work, we reported the synthesis of 23 statine-based peptidomimetics to determine their ability to inhibit the main protease (Mpro) activity of SARS-CoV-2. Among the 23 peptidomimetics, 15 compounds effectively inhibited Mpro activity by 50% or more, while three compounds (7d, 8e, and 9g) exhibited maximum inhibition above 70% and IC50 < 1 µM. Compounds 7d, 8e, and 9g inhibited roughly 80% of SARS-CoV-2 replication and proved no cytotoxicity. Molecular docking simulations show putative hydrogen bond and hydrophobic interactions between specific amino acids and these inhibitors. Molecular dynamics simulations further confirmed the stability and persisting interactions in Mpro's subsites, exhibiting favorable free energy binding (ΔGbind) values. These findings suggest the statine-based peptidomimetics as potential therapeutic agents against SARS-CoV-2 by targeting Mpro.

Synthetic Access to 3-Substituted Pyroglutamic Acids from Tetramate Derivatives of Serine, Threonine, allo-Threonine, and Cysteine

A general route which provides direct access to pyroglutamates from tetramates, making use of Suzuki coupling on an enol mesylate, followed by reduction, is reported. This work permits direct scaffold hopping from tetramate to substituted pyroglutamates. Some compounds in the library showed modest antibacterial activity against Gram-positive bacteria.

3-Acyltetramic acids as a novel class of inhibitors for human kallikreins 5 and 7

Human kallikreins 5 and 7 (KLK5 and KLK7) exhibit trypsin- and chymotrypsin-like activities and are involved in pathologies related to skin desquamation process. A series of new 3-acyltetramic acids were developed as a novel class of inhibitors of KLK5, KLK7 and trypsin enzymes. The nature and length of the acyl chain is crucial to the KLK5, KLK7 and trypsin inhibition activities, and the most potent compounds (but not the most selective) 2b, 2c and 2g showed low micromolar IC₅₀ values. While very few of the compounds were selective for KLK5, the selective inhibition of trypsin against chymotrypsin was achieved. Our molecular modelling studies revealed that the double bond in 2g provided the best fit in the binding site of KLK5, while the hydrogen bonding interactions modulated the best fit of 2c in the binding site of KLK7 due to the hydrophobicity of the cavity.

Nucleophilic ring-opening of epoxide and aziridine acetates for the stereodivergent synthesis of β-hydroxy and β-amino γ-lactams

A highly regio- and stereoselective synthesis of novel β,γ-disubstituted γ-lactams with either an anti or syn relative configuration was developed from readily available epoxide and aziridine acetates. The key steps include the regio- and diastereocontrolled nucleophilic ring-opening of these three-membered heterocycles followed by mild reductive cyclization of the γ-azido ester intermediate. The method was also extended to an asymmetric synthesis of (4R,5S)-4-hydroxy-5-phenylpyrrolidin-2-one from a chiral epoxide acetate. The main features of this versatile synthesis of functionalized γ-lactams include the involvement of inexpensive reagents and mild conditions together with high chemical efficiency.