An alternative approach toward 2-aryl-2H-pyrazolo[4,3-c]-quinolin-3-ones by a multistep synthesis

Design, synthesis, and biological evaluation of novel arylcarboxamide derivatives as anti-tubercular agents

Our group has previously reported several indolecarboxamides exhibiting potent antitubercular activity. Herein, we rationally designed several arylcarboxamides based on our previously reported homology model and the recently published crystal structure of the mycobacterial membrane protein large 3 (MmpL3). Many analogues showed considerable anti-TB activity against drug-sensitive (DS) Mycobacterium tuberculosis (M. tb) strain. Naphthamide derivatives 13c and 13d were the most active compounds in our study (MIC: 6.55, 7.11 μM, respectively), showing comparable potency to the first line anti-tuberculosis (anti-TB) drug ethambutol (MIC: 4.89 μM). In addition to the naphthamide derivatives, we also identified the quinolone-2-carboxamides and 4-arylthiazole-2-carboxamides as potential MmpL3 inhibitors in which compounds 8i and 18b had MIC values of 9.97 and 9.82 μM, respectively. All four compounds retained their high activity against multidrug-resistant (MDR) and extensively drug-resistant (XDR) M. tb strains. It is worth noting that the two most active compounds 13c and 13d also exhibited the highest selective activity towards DS, MDR and XDR M. tb strains over mammalian cells [IC₅₀ (Vero cells) ≥ 227 μM], indicating their potential lack of cytotoxicity. The four compounds were docked into the MmpL3 active site and were studied for their drug-likeness using Lipinski's rule of five.

Synthesis and pharmacological evaluation of arylcarboxamide derivatives based on an antimycobacterial indole-2-carboxamide scaffold. The most active compounds demonstrated activities against MDR and XDR M. tb strains.

Novel Pyrazolo[4, 3-c]Quinolin-3-One Derivatives as PDE5A Inhibitors

BACKGROUND

PDE5A is a phosphodiesterase which specifically hydrolyzes the cGMP to GMP. It takes part in several physiological and pathological pathways and is considered an important drug target. Currently, PDE5 inhibitors (ex; Sildenafil, Tadalafil) available in the market are not only being used for the treatment of erectile dysfunction but at the same time, they are also in clinical trials being investigated as anticancer agents.

MATERIALS & METHODS

In this work, we have examined pyrazolo [4,3-c]quinolin-3-ones as PDE5A inhibitors. Pyrazolo [4,3-c]quinolin-3-ones are the class of tricyclic heterocyclic derivatives having a variety of therapeutically interesting drug candidates known for their anti-inflammatory, anti-viral, anti-anxiety and anti-cancer activity. Therefore, synthetic methods providing access to pyrazolo [4, 3-c] quinolin-3-ones are immensely valuable. Here, we are reporting a simple but efficient route for the synthesis of novel 8-morpholino-2-aryl - 2, 5-dihydro-3H-pyrazolo [4, 3-c] quinolin-3-one derivatives.

RESULTS

Further, molecular docking studies of synthesized compounds with human PDE5A protein showed that all the compounds exhibited good docking score in comparison with known inhibitors. In addition, all the synthesized molecules were evaluated against HCT116 cell lines for their antitumor activity.

CONCLUSION

Among all the synthesized compounds, compound 5a, 5d, and 6e showed better cytotoxicity. Thus, these derivatives can be studied as potential inhibitors of PDE5A.

Synthesis and preliminary structure-activity relationship study of 2-aryl-2H-pyrazolo[4,3-c]quinolin-3-ones as potential checkpoint kinase 1 (Chk1) inhibitors

The serine-threonine checkpoint kinase 1 (Chk1) plays a critical role in the cell cycle arrest in response to DNA damage. In the last decade, Chk1 inhibitors have emerged as a novel therapeutic strategy to potentiate the anti-tumour efficacy of cytotoxic chemotherapeutic agents. In the search for new Chk1 inhibitors, a congeneric series of 2-aryl-2 H-pyrazolo[4,3-c]quinolin-3-one (PQ) was evaluated by in-vitro and in-silico approaches for the first time. A total of 30 PQ structures were synthesised in good to excellent yields using conventional or microwave heating, highlighting that 14 of them are new chemical entities. Noteworthy, in this preliminary study two compounds 4e₂ and 4h₂ have shown a modest but significant reduction in the basal activity of the Chk1 kinase. Starting from these preliminary results, we have designed the second generation of analogous in this class and further studies are in progress in our laboratories.

Novel Synthesis of 2-thienylcarbonyl-cyclohexane-1,3-dione as Building Block for Indazolones and Isoxazolones

A new synthetic methodology using ultrasonic treatment was applied to the C-acylation of 1,3-cyclohexanedione with thiophene-2-carbonyl chloride to afford 3-hydroxy-2-(2-thienylcarbonyl)cyclohex-2-en-1-one (5). This compound was used as a building block to prepare different bicyclic systems: tetrahydro-4H-indazol-4-ones (7a–c and 9a,b,d), and 6,7-dihydrobenzisoxazole (11) by reaction with different hydrazines and hydroxylamine, respectively. Structural elucidation of all compounds was thoroughly achieved by NMR spectroscopy.