Second generation Spautin-1 analogues targeting EGFR-mutant non-small cell lung cancer cells.

Treatment of advanced stage epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is often complicated by the occurrence of acquired resistance, which emphasizes the need for improved treatment options. Based on a previously reported structure-activity relationship (SAR) study of Spautin-1, which resulted in the discovery of 10a, the search for more potent analogues was envisaged through optimization of the amine substituent. Our search led to the discovery of analogue 15b, harbouring the 2-[4-(4-fluoro-phenoxy)-phenyl]ethylamine substituent, among other potent and original analogues, with nanomolar activity towards EGFR-mutant NSCLC cells. Moreover, this compound 15b showed good selectivity for cancer cells over healthy lung epithelial cells and provides additive effects with food and drug administration (FDA) approved EGFR-tyrosine kinase inhibitors (TKIs), as proven by the co-administration of 15b with Afatinib. Altogether, we report promising lead compounds which show the potential to improve current treatment options.

Propargylamine Amino Acids as Constrained Nε-Substituted Lysine Mimetics.

Herein, alkylated propargylamines are reported as constrained lysine mimetics and constructed in a single step using a copper(I)-catalyzed A3-coupling reaction. Using multiple secondary amines, the reaction allowed the generation of a structurally diverse set of N-Fmoc protected amino acid derivatives. In addition, the A3-reaction was applied on solid phase via the assembly of short model tripeptides. Moreover, the internal alkyne moiety allowed further functionalization toward novel 1,4,5-trisubstituted 1,2,3-triazole-based amino acids.

3-Substituted 2-isocyanopyridines as versatile convertible isocyanides for peptidomimetic design.

We report the use of 3-substituted 2-isocyanopyridines as convertible isocyanides in Ugi four-component reactions. The N-(3-substituted pyridin-2-yl)amide Ugi products can be cleaved by amines, alcohols, and water with Zn(OAc)2 as a catalyst. In addition, the applicability of the method was demonstrated in constrained di-/tripeptides bearing acid and base sensitive protective groups obtained via Ugi-4CR post-condensation modifications.

Structure-Activity Relationship (SAR) Study of Spautin-1 to Entail the Discovery of Novel NEK4 Inhibitors.

Lung cancer is one of the most frequently diagnosed cancers accounting for the highest number of cancer-related deaths in the world. Despite significant progress including targeted therapies and immunotherapy, the treatment of advanced lung cancer remains challenging. Targeted therapies are highly efficacious at prolonging life, but not curative. In prior work we have identified Ubiquitin Specific Protease 13 (USP13) as a potential target to significantly enhance the efficacy of mutant EGFR inhibition. The current study aimed to develop lead molecules for the treatment of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) by developing potent USP13 inhibitors initially starting from Spautin-1, the only available USP13 inhibitor. A SAR study was performed which revealed that increasing the chain length between the secondary amine and phenyl group and introducing a halogen capable of inducing a halogen bond at position 4' of the phenyl group, dramatically increased the activity. However, we could not confirm the binding between Spautin-1 (or its analogues) and USP13 using isothermal titration calorimetry (ITC) or thermal shift assay (TSA) but do not exclude binding under physiological conditions. Nevertheless, we found that the anti-proliferative activity displayed by Spautin-1 towards EGFR-mutant NSCLC cells in vitro was at least partially associated with kinase inhibition. In this work, we present N-[2-(substituted-phenyl)ethyl]-6-fluoro-4-quinazolinamines as promising lead compounds for the treatment of NSCLC. These analogues are significantly more effective towards EGFR-mutant NSCLC cells than Spautin-1 and act as potent never in mitosis A related kinase 4 (NEK4) inhibitors (IC50~1 µM) with moderate selectivity over other kinases.

Antimicrobial Activity of a Repurposed Harmine-Derived Compound on Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates.

OBJECTIVES: The spread of antibiotic resistant bacteria is an important threat for human health. Acinetobacter baumannii bacteria impose such a major issue, as multidrug- to pandrug-resistant strains have been isolated, rendering some infections untreatable. In this context, carbapenem-resistant A. baumannii bacteria were ranked as top priority by both WHO and CDC. In addition, A. baumannii bacteria survive in harsh environments, being capable of resisting to disinfectants and to persist prolonged periods of desiccation. Due to the high degree of variability found in A. baumannii isolates, the search for new antibacterials is very challenging because of the requirement of drug target conservation amongst the different strains. Here, we screened a chemical library to identify compounds active against several reference strains and carbapenem-resistant A. baumannii bacteria. METHODS: A repurposing drug screen was undertaken to identify A. baumannii growth inhibitors. One hit was further characterized by determining the IC50 and testing the activity on 43 modern clinical A. baumannii isolates, amongst which 40 are carbapenem-resistant. RESULTS: The repurposing screen led to the identification of a harmine-derived compound, called HDC1, which proves to have bactericidal activity on the multidrug-resistant AB5075-VUB reference strain with an IC50 of 48.23 µM. In addition, HDC1 impairs growth of 43 clinical A. baumannii isolates. CONCLUSIONS: We identified a compound with inhibitory activity on all tested strains, including carbapenem-resistant clinical A. baumannii isolates.