Structural Optimization of the Diarylurea PSNCBAM-1, an Allosteric Modulator of Cannabinoid Receptor 1

CB1 allosteric modulators and their therapeutic potential in CNS disorders

CB1 is the most abundant GPCR found in the mammalian brain. It has garnered considerable attention as a potential therapeutic drug target. CB1 is involved in a wide range of physiological and psychiatric processes and has the potential to be targeted in a wide range of disease states. However, most of the selective and non-selective synthetic CB1 agonists and antagonists/inverse agonists developed to date are primarily used as research tools. No novel synthetic cannabinoids are currently in the clinic for use in psychiatric illness; synthetic analogues of the phytocannabinoid THC are on the market to treat nausea and vomiting caused by cancer chemotherapy, along with off-label use for pain. Novel strategies are being explored to target CB1, but with emphasis on the elimination or mitigation of the potential psychiatric adverse effects that are observed by central agonism/antagonism of CB1. New pharmacological options are being pursued that may avoid these adverse effects while preserving the potential therapeutic benefits of CB1 modulation. Allosteric modulation of CB1 is one such approach. In this review, we will summarize and critically analyze both the in vitro characterization and in vivo validation of CB1 allosteric modulators developed to date, with a focus on CNS therapeutic effects.

Diarylureas: Repositioning from Antitumor to Antimicrobials or Multi-Target Agents against New Pandemics

Antimicrobials have allowed medical advancements over several decades. However, the continuous emergence of antimicrobial resistance restricts efficacy in treating infectious diseases. In this context, the drug repositioning of already known biological active compounds to antimicrobials could represent a useful strategy. In 2002 and 2003, the SARS-CoV pandemic immobilized the Far East regions. However, the drug discovery attempts to study the virus have stopped after the crisis declined. Today’s COVID-19 pandemic could probably have been avoided if those efforts against SARS-CoV had continued. Recently, a new coronavirus variant was identified in the UK. Because of this, the search for safe and potent antimicrobials and antivirals is urgent. Apart from antiviral treatment for severe cases of COVID-19, many patients with mild disease without pneumonia or moderate disease with pneumonia have received different classes of antibiotics. Diarylureas are tyrosine kinase inhibitors well known in the art as anticancer agents, which might be useful tools for a reposition as antimicrobials. The first to come onto the market as anticancer was sorafenib, followed by some other active molecules. For this interesting class of organic compounds antimicrobial, antiviral, antithrombotic, antimalarial, and anti-inflammatory properties have been reported in the literature. These numerous properties make these compounds interesting for a new possible pandemic considering that, as well as for other viral infections also for CoVID-19, a multitarget therapeutic strategy could be favorable. This review is meant to be an overview on diarylureas, focusing on their biological activities, not dwelling on the already known antitumor activity. Quite a lot of papers present in the literature underline and highlight the importance of these molecules as versatile scaffolds for the development of new and promising antimicrobials and multitarget agents against new pandemic events.

PSNCBAM-1 analogs: Structural evolutions and allosteric properties at cannabinoid CB1 receptor

Allosteric modulation of the CB1Rs could represent an alternative strategy for the treatment of diseases in which these receptors are involved, without the undesirable effects associated with their orthosteric stimulation. PSNCBAM-1 is a reference diaryl urea derivative that positively affects the binding affinity of orthosteric ligands (PAM) and negatively affects the functional activity of orthosteric ligands (NAM) at CB1Rs. In this work we reported the design, synthesis and biological evaluation of three different series of compounds, derived from structural modifications of PSNCBAM-1 and its analogs reported in the recent literature. Almost all the new compounds increased the percentage of binding affinity of CP55940 at CB1Rs, showing a PAM profile. When tested alone in the [³⁵S]GTPγS functional assay, only a few derivatives lacked detectable activity, so were tested in the same functional assay in the presence of CP55940. Among these, compounds 11 and 18 proved to be functional NAMs at CB1Rs, dampening the orthosteric agonist-induced receptor functionality by approximately 30%. The structural features presented in this work provide new CB1R-allosteric modulators (with a profile similar to the reference compound PSNCBAM-1) and an extension of the structure-activity relationships for this type of molecule at CB1Rs.