Synthesis and antimicrobial activity of N-(4-chlorophenyl)-β-alanine derivatives with an azole moiety

Screening of Small-Molecule Libraries Using SARS-CoV-2-Derived Sequences Identifies Novel Furin Inhibitors

SARS-CoV-2 is the pathogen responsible for the most recent global pandemic, which has claimed hundreds of thousands of victims worldwide. Despite remarkable efforts to develop an effective vaccine, concerns have been raised about the actual protection against novel variants. Thus, researchers are eager to identify alternative strategies to fight against this pathogen. Like other opportunistic entities, a key step in the SARS-CoV-2 lifecycle is the maturation of the envelope glycoprotein at the RARR685↓ motif by the cellular enzyme Furin. Inhibition of this cleavage greatly affects viral propagation, thus representing an ideal drug target to contain infection. Importantly, no Furin-escape variants have ever been detected, suggesting that the pathogen cannot replace this protease by any means. Here, we designed a novel fluorogenic SARS-CoV-2-derived substrate to screen commercially available and custom-made libraries of small molecules for the identification of new Furin inhibitors. We found that a peptide substrate mimicking the cleavage site of the envelope glycoprotein of the Omicron variant (QTQTKSHRRAR-AMC) is a superior tool for screening Furin activity when compared to the commercially available Pyr-RTKR-AMC substrate. Using this setting, we identified promising novel compounds able to modulate Furin activity in vitro and suitable for interfering with SARS-CoV-2 maturation. In particular, we showed that 3-((5-((5-bromothiophen-2-yl)methylene)-4-oxo-4,5 dihydrothiazol-2-yl)(3-chloro-4-methylphenyl)amino)propanoic acid (P3, IC50 = 35 μM) may represent an attractive chemical scaffold for the development of more effective antiviral drugs via a mechanism of action that possibly implies the targeting of Furin secondary sites (exosites) rather than its canonical catalytic pocket. Overall, a SARS-CoV-2-derived peptide was investigated as a new substrate for in vitro high-throughput screening (HTS) of Furin inhibitors and allowed the identification of compound P3 as a promising hit with an innovative chemical scaffold. Given the key role of Furin in infection and the lack of any Food and Drug Administration (FDA)-approved Furin inhibitor, P3 represents an interesting antiviral candidate.

Synthesis and Development of N-2,5-Dimethylphenylthioureido Acid Derivatives as Scaffolds for New Antimicrobial Candidates Targeting Multidrug-Resistant Gram-Positive Pathogens

The growing antimicrobial resistance to last-line antimicrobials among Gram-positive pathogens remains a major healthcare emergency worldwide. Therefore, the search for new small molecules targeting multidrug-resistant pathogens remains of great importance. In this paper, we report the synthesis and in vitro antimicrobial activity characterisation of novel thiazole derivatives using representative Gram-negative and Gram-positive strains, including tedizolid/linezolid-resistant S. aureus, as well as emerging fungal pathogens. The 4-substituted thiazoles 3h, and 3j with naphthoquinone-fused thiazole derivative 7 with excellent activity against methicillin and tedizolid/linezolid-resistant S. aureus. Moreover, compounds 3h, 3j and 7 showed favourable activity against vancomycin-resistant E. faecium. Compounds 9f and 14f showed broad-spectrum antifungal activity against drug-resistant Candida strains, while ester 8f showed good activity against Candida auris which was greater than fluconazole. Collectively, these data demonstrate that N-2,5-dimethylphenylthioureido acid derivatives could be further explored as novel scaffolds for the development of antimicrobial candidates targeting Gram-positive bacteria and drug-resistant pathogenic fungi.

Acid-triggered degradable polyprodrug with drug as unique repeating unit for long-acting drug delivery with minimal leakage

Acid-triggered degradable polyprodrug P(DOX-AH) was designed for long-acting drug delivery with minimal leakage and enhanced antitumor efficacy. By facile polymerization of doxorubicin (DOX) and N-(tert-butoxycarbonyl)acryloylhydrazine (Boc-AH), P(DOX-AH) with drug as unique repeating unit was obtained, possessing an ultrahigh drug content. It was stable in the neutral media but could degrade completely into DOX-AH in the acidic media without any other by-product. The cleavage of the hydrazone linkage between the DOX-AH repeating units was revealed by the LC-MS/MS analysis. Furthermore, a slow solubility-controlled drug release performance was achieved in the acidic media because of the low solubility of the released DOX-AH. Even with the slow DOX-AH releasing, the enhanced antitumor efficacy was obtained than free DOX in the in vitro cellular experiments. These features demonstrated the promising potential of the proposed polyprodrug for long-acting drug delivery in future tumor chemotherapy.

Raposo MM, Costa SPG. Heterocyclic amino acids as fluorescent reporters for transition metals: synthesis and evaluation of novel furyl-benzoxazol-5-yl-l-alanines

Novel benzoxazol-5-yl-l-alanines with heterocyclic pendants were synthesized and investigated as fluorescent reporters for metal cations through spectrofluorimetric titrations.

Synthesis and antimicrobial activity of N-substituted-β-amino acid derivatives containing 2-hydroxyphenyl, benzo[b]phenoxazine and quinoxaline moieties

3-[(2-Hydroxyphenyl)amino]butanoic and 3-[(2-hydroxy-5-methyl(chloro)phenyl)amino]butanoic acids were converted to a series of derivatives containing hydrazide, pyrrole and chloroquinoxaline moieties. The corresponding benzo[b]phenoxazine derivatives were synthesized by the reaction of the obtained compounds with 2,3-dichloro-1,4-naphthoquinone. Five of the synthesized compounds exhibited good antimicrobial activity against Staphylococcus aureus and Mycobacterium luteum, whereas three compounds showed significant antifungal activity against Candida tenuis and Aspergillus niger.

4-amino-substituted benzenesulfonamides as inhibitors of human carbonic anhydrases

A series of N-aryl-β-alanine derivatives and diazobenzenesulfonamides containing aliphatic rings were designed, synthesized, and their binding to carbonic anhydrases (CA) I, II, VI, VII, XII, and XIII was studied by the fluorescent thermal shift assay and isothermal titration calorimetry. The results showed that 4-substituted diazobenzenesulfonamides were more potent CA binders than N-aryl-β-alanine derivatives. Most of the N-aryl-β-alanine derivatives showed better affinity for CA II while diazobenzenesulfonamides possessed nanomolar affinities towards CA I isozyme. X-ray crystallographic structures showed the modes of binding of both compound groups.