Why PB28 Could Be a Covid 2019 Game Changer?

The N,N,O-Trisubstituted Hydroxylamine Isostere and Its Influence on Lipophilicity and Related Parameters

The influence of substitution of an N,N,O-trisubstituted hydroxylamine (-NR-OR'-) unit for a hydrocarbon (-CHR-CH2-), ether (-CHR-OR'-), or amine (-NR-CHR'-) moiety on lipophilicity and other ADME parameters is described. A matched molecular pair analysis was conducted across five series of compounds, which showed that the replacement of carbon-carbon bonds by N,N,O-trisubstituted hydroxylamines typically leads to a reduction in logP comparable to that achieved with a tertiary amine group. In contrast, the weakly basic N,N,O-trisubstituted hydroxylamines have greater logD 7.4 values than tertiary amines. It is also demonstrated that the N,N,O-trisubstituted hydroxylamine moiety can improve metabolic stability and reduce human plasma protein binding relative to the corresponding hydrocarbon and ether units. Coupled with recent synthetic methods for hydroxylamine assembly by N-O bond formation, these results provide support for the re-evaluation of the N,N,O-trisubstituted hydroxylamine moiety in small-molecule optimization schemes in medicinal chemistry.

Biophysical Evaluation and In Vitro Controlled Release of Two Isomeric Adamantane Phenylalkylamines with Antiproliferative/Anticancer and Analgesic Activity

The aqueous dissolution profile of the isomeric synthetic adamantane phenylalkylamine hydrochlorides I and II was probed. These adducts have shown significant antiproliferative/anticancer activity associated with an analgesic profile against neuropathic pain. They are both devoid of toxic effects and show appreciable enzymatic human plasma stability. The structures of these two compounds have been elucidated using 2D NMR experiments, which were used to study their predominant conformations. Compound II’s scaffold appeared more flexible, as shown by the NOE spatial interactions between the alkyl bridge chain, the aromatic rings, and the adamantane nucleus. Conversely, compound I appeared very rigid, as it did not share significant NOEs between the aforementioned structural segments. MD simulations confirmed the NOE results. The aqueous dissolution profile of both molecules fits well with their minimum energy conformers’ features, which stem from the NOE data; this was nicely demonstrated, especially in the case of compound II.

Recent Advances in the Development of Sigma Receptor Ligands as Cytotoxic Agents: A Medicinal Chemistry Perspective

Since their discovery as distinct receptor proteins, the specific physiopathological role of sigma receptors (σRs) has been deeply investigated. It has been reported that these proteins, classified into two subtypes indicated as σ₁ and σ₂, might play a pivotal role in cancer growth, cell proliferation, and tumor aggressiveness. As a result, the development of selective σR ligands with potential antitumor properties attracted significant attention as an emerging theme in cancer research. This perspective deals with the recent advances of σR ligands as novel cytotoxic agents, covering articles published between 2010 and 2020. An up-to-date description of the medicinal chemistry of selective σ₁R and σ₂R ligands with antiproliferative and cytotoxic activities has been provided, including major pharmacophore models and comprehensive structure–activity relationships for each main class of σR ligands.

Drugs that offer the potential to reduce hospitalization and mortality from SARS-CoV-2 infection: The possible role of the sigma-1 receptor and autophagy

Introduction: Despite the availability of new vaccines for SARS-CoV-2, there has been slow uptake and problems with supply in some parts of the world. Hence, there is still a necessity for drugs that can prevent hospitalization of patients and reduce the strain on health care systems. Drugs with sigma affinity potentially provide protection against the most severe symptoms of SARS-COV-2 and could prevent mortality via interactions with the sigma-1 receptor.Areas covered: This review examines the role of the sigma-1 receptor and autophagy in SARS-CoV-2 infections and how they may be linked. The authors reveal how sigma ligands may reduce the symptoms, complications, and deaths resulting from SARS-CoV-2 and offer insights on those patient cohorts that may benefit most from these drugs.Expert opinion: Drugs with sigma affinity potentially offer protection against the most severe symptoms of SARS-CoV-2 via interactions with the sigma-1 receptor. Agonists of the sigma-1 receptor may provide protection of the mitochondria, activate mitophagy to remove damaged and leaking mitochondria, prevent ER stress, manage calcium ion transport, and induce autophagy to prevent cell death in response to infection.

PB28, the Sigma-1 and Sigma-2 Receptors Modulator With Potent Anti-SARS-CoV-2 Activity: A Review About Its Pharmacological Properties and Structure Affinity Relationships

These unprecedented times have forced the scientific community to gather to face the COVID-19 pandemic. Efforts in diverse directions have been made. A multi-university team has focused on the identification of the host (human) proteins interacting with SARS-CoV-2 viral proteins, with the aim of hampering these interactions that may cause severe COVID-19 symptoms. Sigma-1 and sigma-2 receptors surprisingly belong to the “druggable” host proteins found, with the pan-sigma receptor modulator PB28 displaying the most potent anti–SARS-CoV-2 activity in in vitro assays. Being 20-fold more active than hydroxychloroquine, without cardiac side effects, PB28 is a promising antiviral candidate worthy of further investigation. Our research group developed PB28 in 1996 and have thoroughly characterized its biological properties since then. Structure–affinity relationship (SAfiR) studies at the sigma receptor subtypes were also undertaken with PB28 as the lead compound. We herein report our knowledge of PB28 to share information that may help to gain insight into the antiviral action of this compound and sigma receptors, while providing structural hints that may speed up the translation into therapeutics of this class of ligands.