Neuropathic pain (NP) is a chronic condition resulting from damaged pain-signaling pathways. It is a debilitating disorder that affects up to 10% of the world’s population. Although opioid analgesics are effective in reducing pain, they present severe risks; so, there is a pressing need for non-opioid pain-relieving drugs. One potential alternative is represented by sigma-1 receptor (S1R) antagonists due to their promising analgesic effects. Here, we report the synthesis and biological evaluation of a series of S1R antagonists based on a 2-aryl-4-aminobutanol scaffold. After assessing affinity toward the S1R and selectivity over the sigma-2 receptor (S2R), we evaluated the agonist/antagonist profile of the compounds by investigating their effects on nerve growth factor-induced neurite outgrowth and aquaporin-mediated water permeability in the presence and absence of oxidative stress. (R/S)-RC-752 emerged as the most interesting compound for S1R affinity (K_i S1R = 6.2 ± 0.9) and functional antagonist activity. Furthermore, it showed no cytotoxic effect in two normal human cell lines or in an in vivo zebrafish model and was stable after incubation in mouse plasma. (R/S)-RC-752 was then evaluated in two animal models of NP: the formalin test and the spinal nerve ligation model. The results clearly demonstrated that compound (R/S)-RC-752 effectively alleviated pain in both animal models, thus providing the proof of concept of its efficacy as an antinociceptive agent.

The insurgence of drug resistance in treating Multiple Myeloma (MM) still represents a major hamper in finding effective treatments, although over the past decades new classes of drugs, such as proteasome inhibitors and immunomodulatory drugs, have been discovered. Recently, our research team, within a Nature-Aided Drug Discovery project, isolated from Hibiscus Sabdariffa L. calyces the secondary metabolite called Hib-ester which possesses antiproliferative properties against human multiple myeloma RPMI 8226 cells, reduces migration and cell invasion and inhibits proteasome without neurotoxic effects. In the present study, we explored the chemical spaces of the hit compound Hib-ester. We explored the structure-activity relationships (SAR), and we optimized the scaffold through sequentially modifying Hib-ester subunits. Compound screening was performed based on cytotoxicity against the RPMI 8226 cells to assess the potential efficacy toward human MM. The ability of the most effective molecules to inhibit the proteasome was evaluated and the binding mode of the most promising compounds in the proteasome chymotrypsin binding pocket was deciphered through molecular modeling simulations. Compounds 13 and 14 are more potent than Hib-ester, demonstrating that our strategy was suitable for the identification of a novel chemotype for developing possible drug candidates and hopefully widening the drug armamentarium against MM.

LsrK is a bacterial kinase that triggers the quorum sensing, and it represents a druggable target for the identification of new agents for fighting antimicrobial resistance. Herein, we exploited tryptophan fluorescence spectroscopy (TFS) as a suitable technique for the identification of potential LsrK ligands from an in-house library of chemicals comprising synthetic compounds as well as secondary metabolites. Three secondary metabolites (Hib-ester, Hib-carbaldehyde and (R)-ASME) showed effective binding to LsrK, with KD values in the sub-micromolar range. The conformational changes were confirmed via circular dichroism and molecular docking results further validated the findings and displayed the specific mode of interaction. The activity of the identified compounds on the biofilm formation by some Staphylococcus spp. was investigated. Hib-carbaldehyde and (R)-ASME were able to reduce the production of biofilm, with (R)-ASME resulting in the most effective compound with an EC₅₀ of 14 mg/well. The successful application of TFS highlights its usefulness in searching for promising LsrK inhibitor candidates with inhibitor efficacy against biofilm formation.

The 1,3-dithiolane ring has been recently rehabilitated as a chemical scaffold in drug design. However, for derivatives that are substituted in position 4, the introduction of a chiral center on the heterocycle demands the separation and characterization of the stereoisomers. We report the first chiral resolution and absolute configuration (AC) assignment for (1,4-dithiaspiro[4.5]decan-2-yl)methanol (R/S)-1, a key synthon for dithiolane-based biologically active compounds. Using (semi)preparative enantioselective HPLC, we isolated enantiomeric 1. The AC was assigned by using (+)-1 for the enantioselective synthesis of (+)-BS148, a sigma receptor modulator. An X-ray diffraction analysis established the (R)-configuration of (+)-BS148 and, by extension, of (+)-1. This method provides a reliable approach for preparing enantiopure 1,3-dithiolane scaffolds and establishes reference standards for AC determination of related compounds.

Antibiotic-resistant infections remain a major challenge in cystic fibrosis (CF), where chronic Pseudomonas aeruginosa colonization drives lung infection. The overexpression of adhesion-related proteins and extracellular matrix components, including fibronectin (Fn), facilitates bacterial colonization. Recent evidence identifies the RNA-binding protein Human Antigen R (HuR) as a key regulator of this process, as it stabilizes Vav3 mRNA, promoting Fn deposition and the formation of bacterial docking platforms. Here, we report the synthesis, optimization, and functional evaluation of the HuR-targeted small-molecule (2S,3S)-BOPC1. Functional assays in CF human airway epithelial cells demonstrated that (2S,3S)-BOPC1 significantly reduced P. aeruginosa adhesion in a dose-dependent manner without detectable cytotoxic effects. These findings provide the first evidence that targeting HuR can disrupt the HuR–Vav3–Fn axis, reducing bacterial attachment. This host-directed approach represents a promising strategy to prevent chronic infections in CF without promoting antibiotic resistance.

Antibiotic-resistant infections remain a major challenge in cystic fibrosis (CF), where chronic Pseudomonas aeruginosa colonization drives lung infection. The overexpression of adhesion-related proteins and extracellular matrix components, including fibronectin (Fn), facilitates bacterial colonization. Recent evidence identifies the RNA-binding protein Human Antigen R (HuR) as a key regulator of this process, as it stabilizes Vav3 mRNA, promoting Fn deposition and the formation of bacterial docking platforms. Here, we report the synthesis, optimization, and functional evaluation of the HuR-targeted small-molecule (2S,3S)-BOPC1. Functional assays in CF human airway epithelial cells demonstrated that (2S,3S)-BOPC1 significantly reduced P. aeruginosa adhesion in a dose-dependent manner without detectable cytotoxic effects. These findings provide the first evidence that targeting HuR can disrupt the HuR–Vav3–Fn axis, reducing bacterial attachment. This host-directed approach represents a promising strategy to prevent chronic infections in CF without promoting antibiotic resistance.