Investigation of 5’-norcarbocyclic nucleoside analogues as antiprotozoal and antibacterial agents

Carbocyclic nucleosides have long played a role in antiviral, antiparasitic, and antibacterial therapies. Recent results from our laboratories from two structurally related scaffolds have shown promising activity against both Mycobacterium tuberculosis and several parasitic strains. As a result, a small structure activity relationship study was designed to further probe their activity and potential. Their synthesis and the results of the subsequent biological activity are reported herein

Synthetic Optimizations for Gram-Scale Preparation of 1-O-Methyl d-Glycero-α-d-gluco-heptoside 7-Phosphate from d-Glucose

Heptose phosphates—unique linkers between endotoxic lipid A and O-antigen in the bacterial membrane—are pathogen-associated molecular patterns recognized by the receptors of the innate immune system. Understanding the mechanisms of immune system activation is important for the development of therapeutic agents to combat infectious diseases and overcome antibiotic resistance. However, in practice, it is difficult to obtain a substantial amount of heptose phosphates for biological studies due to the narrow scope of the reported synthetic procedures. We have optimized and developed an inexpensive and convenient synthesis for the first performed gram-scale production of 1-O-methyl d-glycero-α-d-gluco-heptoside 7-phosphate from readily available d-glucose. Scaling up to such amounts of the product, we have increased the efficiency of the synthesis and reduced the number of steps of the classical route through the direct phosphorylation of the O6,O7-unprotected heptose. The refined method could be of practical value for further biological screening of heptose phosphate derivatives

Novel 5′-Norcarbocyclic Derivatives of Bicyclic Pyrrolo- and Furano[2,3-d]Pyrimidine Nucleosides

Here we report the synthesis and biological activity of new 5′-norcarbocyclic derivatives of bicyclic pyrrolo- and furano[2,3-d]pyrimidines with different substituents in the heterocyclic ring. Lead compound 3i, containing 6-pentylphenyl substituent, displays inhibitory activity with respect to a number of tumor cells with a moderate selectivity index value. Compound 3i induces cell death by the apoptosis pathway with the dissipation of mitochondrial potential

Synthesis of the Indole-Based Inhibitors of Bacterial Cystathionine γ-Lyase NL1-NL3

Bacterial cystathionine γ-lyase (bCSE) is the main producer of H2S in pathogenic bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, etc. The suppression of bCSE activity considerably enhances the sensitivity of bacteria to antibiotics. Convenient methods for the efficient synthesis of gram quantities of two selective indole-based bCSE inhibitors, namely (2-(6-bromo-1H-indol-1-yl)acetyl)glycine (NL1), 5-((6-bromo-1H-indol-1-yl)methyl)- 2-methylfuran-3-carboxylic acid (NL2), as well as a synthetic method for preparation 3-((6-(7-chlorobenzo[b]thiophen-2-yl)-1H-indol-1-yl)methyl)- 1H-pyrazole-5-carboxylic acid (NL3), have been developed. The syntheses are based on the use of 6-bromoindole as the main building block for all three inhibitors (NL1, NL2, and NL3), and the designed residues are assembled at the nitrogen atom of the 6-bromoindole core or by the substitution of the bromine atom in the case of NL3 using Pd-catalyzed cross-coupling. The developed and refined synthetic methods would be significant for the further biological screening of NL-series bCSE inhibitors and their derivatives

Modulation of Cell Death Pathways by Hepatitis C Virus Proteins in Huh7.5 Hepatoma Cells

The hepatitis C virus (HCV) causes chronic liver disease leading to fibrosis, cirrhosis, and hepatocellular carcinoma. HCV infection triggers various types of cell death which contribute to hepatitis C pathogenesis. However, much is still unknown about the impact of viral proteins on them. Here we present the results of simultaneous immunocytochemical analysis of markers of apoptosis, autophagy, and necrosis in Huh7.5 cells expressing individual HCV proteins or their combinations, or harboring the virus replicon. Stable replication of the full-length HCV genome or transient expression of its core, Е1/Е2, NS3 and NS5B led to the death of 20–47% cells, 72 h posttransfection, whereas the expression of the NS4A/B, NS5A or NS3-NS5B polyprotein did not affect cell viability. HCV proteins caused different impacts on the activation of caspases-3, -8 and -9 and on DNA fragmentation. The structural core and E1/E2 proteins promoted apoptosis, whereas non-structural NS4A/B, NS5A, NS5B suppressed apoptosis by blocking various members of the caspase cascade. The majority of HCV proteins also enhanced autophagy, while NS5A also induced necrosis. As a result, the death of Huh7.5 cells expressing the HCV core was induced via apoptosis, the cells expressing NS3 and NS5B via autophagy-associated death, and the cells expressing E1/E2 glycoproteins or harboring HCV the replicon via both apoptosis and autophagy

Novel 5′-Norcarbocyclic Pyrimidine Derivatives as Antibacterial Agents

A series of novel 5′-norcarbocyclic derivatives of 5-alkoxymethyl or 5-alkyltriazolyl-methyl uracil were synthesized and the activity of the compounds evaluated against both Gram-positive and Gram-negative bacteria. The growth of Mycobacterium smegmatis was completely inhibited by the most active compounds at a MIC99 of 67 μg/mL (mc2155) and a MIC99 of 6.7⁻67 μg/mL (VKPM Ac 1339). Several compounds also showed the ability to inhibit the growth of attenuated strains of Mycobacterium tuberculosis ATCC 25177 (MIC99 28⁻61 μg/mL) and Mycobacterium bovis ATCC 35737 (MIC99 50⁻60 μg/mL), as well as two virulent strains of M. tuberculosis; a laboratory strain H37Rv (MIC99 20⁻50 μg/mL) and a clinical strain with multiple drug resistance MS-115 (MIC99 20⁻50 μg/mL). Transmission electron microscopy (TEM) evaluation of M. tuberculosis H37Rv bacterial cells treated with one of the compounds demonstrated destruction of the bacterial cell wall, suggesting that the mechanism of action for these compounds may be related to their interactions with bacteria cell walls