Study on the regioselectivity of the N-ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide.

4-Oxoquinolines are a class of organic substances of great importance in medicinal chemistry, due to their biological and synthetic versatility. N-1-Alkylated-4-oxoquinoline derivatives have been associated with different pharmacological activities such as antibacterial and antiviral. The presence of a carboxamide unit connected to carbon C-3 of the 4-oxoquinoline core has been associated with various biological activities. Experimentally, the N-ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide occurs at the nitrogen of the oxoquinoline group, in a regiosselective way. In this work, we employed DFT methods to investigate the regiosselective ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide, evaluating its acid/base behavior and possible reaction paths.

1,2,3-Triazolyl-4-oxoquinolines: A feasible beginning for promising chemical structures to inhibit oseltamivir-resistant influenza A and B viruses.

We described the synthesis of a new congener series of 1,2,3-triazolyl-4-oxoquinolines and evaluated their ability to inhibit oseltamivir (OST)-resistant influenza strains. Oxoquinoline derivative 1i was the most potent compound within this series, inhibiting 94% of wild-type (WT) influenza neuraminidase (NA) activity. Compound 1i inhibited influenza virus replication with an EC50 of 0.2µM with less cytotoxicity than OST, and also inhibited different OST-resistant NAs. These results suggest that 1,2,3-triazolyl-4-oxoquinolines represent promising lead molecules for further anti-influenza drug design.

Synthesis, cytotoxicity and mechanistic evaluation of 4-oxoquinoline-3-carboxamide derivatives: finding new potential anticancer drugs.

As part of a continuing search for new potential anticancer candidates, we describe the synthesis, cytotoxicity and mechanistic evaluation of a series of 4-oxoquinoline-3-carboxamide derivatives as novel anticancer agents. The inhibitory activity of compounds 10-18 was determined against three cancer cell lines using the MTT colorimetric assay. The screening revealed that derivatives 16b and 17b exhibited significant cytotoxic activity against the gastric cancer cell line but was not active against a normal cell line, in contrast to doxorubicin, a standard chemotherapeutic drug in clinical use. Interestingly, no hemolytical activity was observed when the toxicity of 16b and 17b was tested against blood cells. The in silico and in vitro mechanistic evaluation indicated the potential of 16b as a lead for the development of novel anticancer agents against gastric cancer cells.

Design, synthesis, in vitro and in silico studies of novel 4-oxoquinoline ribonucleoside derivatives as HIV-1 reverse transcriptase inhibitors.

Human immunodeficiency virus type 1 (HIV-1) is a public health problem that affects over 38 million people worldwide. Although there are highly active antiretroviral therapies, emergence of antiviral resistant strains is a problem which leads to almost a million death annually. Thus, the development of new drugs is necessary. The viral enzyme reverse transcriptase (RT) represents a validated therapeutic target. Because the oxoquinolinic scaffold has substantial biological activities, including antiretroviral, a new series of 4-oxoquinoline ribonucleoside derivatives obtained by molecular hybridization were studied here. All synthesized compounds were tested against human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT), and 9a and 9d displayed the highest antiviral activities, with IC50 values of 1.4 and 1.6 µM, respectively. These compounds were less cytotoxic than AZT and showed CC50 values of 1486 and 1394 µM, respectively. Molecular docking studies showed that the most active compounds bound to the allosteric site of the enzyme, suggesting a low susceptibility to the development of antiviral resistance. In silico pharmacokinetic and toxicological evaluations reinforced the potential of the active compounds as anti-HIV candidates for further exploration. Overall, this work showed that compounds 9a and 9d are promising scaffold for future anti-HIV-1 RT drug design.