Synthesis and biological evaluation of new quinoline derivatives as antileishmanial and antitrypanosomal agents

As a part of our project aimed at developing new safe chemotherapeutic agents against tropical diseases, a series of aryl derivatives of 2- and 3-aminoquinoline, some of them new compounds, was designed, synthesized, and evaluated as antiproliferative agents against Trypanosoma cruzi, the parasite responsible for American trypanosomiasis (Chagas' disease), and Leishmania mexicana, the etiological agent of Leishmaniasis. Some of them showed a remarkable activity as parasite growth inhibitors. Fluorine-containing derivatives 11b and 11c were more than twice more potent than geneticin against intracellular promastigote form of Leishmania mexicana exhibiting both IC₅₀ values of 41.9 μM. The IC₅₀ values corresponding to fluorine and chlorine derivatives 11b-d were in the same order than benznidazole against epimastigote form. These drugs are interesting examples of effective antiparasitic agents with outstanding potential not only as lead drugs but also to be used for further in vivo studies. In addition, the obtained compounds showed no toxicity in Vero cells, which makes them good candidates to control tropical diseases. Regarding the probable mode of action, assayed quinoline derivatives interacted with hemin, inhibiting its degradation and generating oxidative stress that is not counteracted by the antioxidant defense system of the parasite.

Synthesis, characterization, biological evaluation and molecular docking studies of 2-(1H-benzo[d]imidazol-2-ylthio)-N-(substituted 4-oxothiazolidin-3-yl) acetamides

BACKGROUND

A series of 2-(1H-benzo[d]imidazol-2-ylthio)-N-(substituted 4-oxothiazolidin-3-yl) acetamides was synthesized and characterized by physicochemical and spectral means. The synthesized compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans and Aspergillus niger by tube dilution method. The in vitro cytotoxicity study of the compounds was carried out against human colorectal (HCT116) cell line. The most promising anticancer derivatives (5l, 5k, 5i and 5p) were further docked to study their binding efficacy to the active site of the cyclin-dependent kinase-8.

RESULTS

All the compounds possessed significant antimicrobial activity with MIC in the range of 0.007 and 0.061 µM/ml. The cytotoxicity study revealed that almost all the derivatives were potent in inhibiting the growth of HCT116 cell line in comparison to the standard drug 5-fluorouracil. Compounds 5l and 5k (IC₅₀ = 0.00005 and 0.00012 µM/ml, respectively) were highly cytotoxic towards HCT116 cell line in comparison to 5-fluorouracil (IC₅₀ = 0.00615 µM/ml) taken as standard drug.

CONCLUSION

The molecular docking studies of potent anticancer compounds 5l, 5k, 5i and 5p showed their putative binding mode and significant interactions with cyclin-dependent kinase-8 as prospective agents for treating colon cancer.

Imidoyl dichlorides as new reagents for the rapid formation of 2-aminobenzimidazoles and related azoles

The development of a reagent for the efficient synthesis of 5- and 6-membered azoles at room temperature is proposed. A variety of substituted 2-aminobenzimidazoles are synthesized in good to excellent yields. The ability to incorporate various protecting groups makes the imidoyl dichloride reagent amenable to a large number of syntheses. The reagent is applied to the total synthesis of the 2-aminobenzimidazole containing carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), from 2-chloro-3-nitropyridine in >60 % yield in 6 steps.

Chloroquine-based hybrid molecules as promising novel chemotherapeutic agents

Chloroquine (CQ) has a broad spectrum of pharmacological activities including anticancer and anti-inflammatory, in addition to its well-known antimalarial activity. This very useful property of CQ may be rendered through a variety of different molecular and cellular mechanisms, including the induction of apoptosis, necrosis and lysosomal dysfunction. CQ alone may not be as effective as many well-known anticancer drugs; however, it often shows synergisticts when combined with other anticancer agents, without causing substantial ill-effects. To increase its pharmacological activity, scientists synthesized many different chloroquine derivatives by a repositioning approach, some of which show higher activities than the parental CQ. To further improve anticancer activity, medicinal chemists have recently been focusing on generating CQ hybrid molecules by joining, directly or through a linker, 4-aminoquinoline and other pharmacologically active phamarcophore(s). Indeed, some CQ hybrid molecules substantially improved anticancer activity while maintaining desirable CQ property, providing an excellent opportunity of developing effective and safe novel anticancer agents. Since the approach of developing CQ hybrid molecules has advanced much more in the antimalarial drug research, it can provide an excellent template for anticancer drug development. This review provides an overview of CQ-based hybrid molecules by focusing on: (1) the potential advantage of the hybrid approach in developing effective and safe anticancer agents; (2) what we can learn from the CQ hybrid approach used in the development of effective antimalarial agents; and (3) CQ hybrid molecules as potential anticancer agents in different categories classified based on their chemical compositions.