MnO2-Mediated Oxidative Cyclization of "Formal" Schiff's Bases: Easy Access to Diverse Naphthofuro-Annulated Triazines

A different type of MnO₂-induced oxidative cyclization of dihydrotriazines has been developed. These dihydrotriazines are considered as a "formal" Schiff's base. This method provided easy access to naphthofuro-fused triazine via the C-C/C-O oxidative coupling reaction. The reaction sequence comprised the nucleophilic addition of 2-naphthol or phenol to 1,2,4-triazine, followed by oxidative cyclization. The scope and limitations of this novel coupling reaction have been investigated. Further application of the synthesized compound has been demonstrated by synthesizing carbazole-substituted benzofuro-fused triazines. The scalability of the reaction was demonstrated at a 40 mmol load. The mechanistic study strongly suggests that this reaction proceeds through the formation of an O-coordinated manganese complex.

Pd catalyzed facile synthesis of cyclopenta[b]quinolin-1-one via sequential Sonogashira coupling and annulation. An unusual mode of ring closure, using sulphur as a soft nucleophile

Pd mediated one pot sequential Sonogashira coupling followed by annulation using o-alkynyl aldehyde is reported.

Structure-activity relationship studies of 4-methylcoumarin derivatives as anticancer agents

CONTEXT

Cancer is a leading cause of death worldwide and novel chemotherapeutic agents with better efficacy and safety profiles are much needed. Coumarins are natural polyphenolic compounds with important pharmacological activities, which are present in many dietary plants and herbal remedies.

OBJECTIVES

The objective of this study is to investigate natural and synthetic coumarin derivatives with considerable anticancer capacity against three human cancer cell lines.

MATERIALS AND METHODS

We synthesized 27 coumarin derivatives (mostly having 4-methyl moiety) and examined their cytotoxic effect on three human cancer cell lines, K562 (chronic myelogenous leukemia), LS180 (colon adenocarcinoma), and MCF-7 (breast adenocarcinoma) by MTT reduction assay. Screened compounds included 7-hydroxy-4-methylcoumarins (7-HMCs), 7-acetoxy-4-methylcoumarins (7-AMCs), and different dihydroxy-4-methylcoumarin (DHMC) and diacetoxy-4-methylcoumarin (DAMC) derivatives. Some compounds with methoxy, amine, and bromine substitutions were also examined.

RESULTS

7,8-DHMCs bearing alkyl groups at C3 position were the most effective subgroup, and of which, the most potent is compound 11, with an n-decyl chain at C3, which had IC50 values of 42.4, 25.2, and 25.1 µM against K562, LS180, and MCF-7 cells, respectively. The second most active subgroup was 7,8-DAMCs containing ethoxycarbonylmethyl and ethoxycarbonylethyl moieties at C3 position. Compound 27 (6-bromo-4-bromomethyl-7-hydroxycoumarin), the only derivative containing bromine also showed reasonable cytotoxic activities (IC50 range: 32.7-45.8 µM).

DISCUSSION AND CONCLUSION

This structure-activity relationship (SAR) study of 4-methylcoumarins shows that further investigation of these derivatives may lead to the discovery of novel anticancer agents.

Novel 9-(alkylthio)-Acenaphtho[1,2-e]-1,2,4-triazine derivatives: synthesis, cytotoxic activity and molecular docking studies on B-cell lymphoma 2 (Bcl-2)

Background and purpose of the study

Acenaphtho derivatives have been reported as antitumor agents. Due to this fact and also with the aim of developing the chemistry of potentially bioactive heterocyclic compounds via efficient reactions, a facile procedure for the synthesis of 9-(alkylthio)-acenaphtho[1,2-e]-1,2,4-triazines via two step condensation of thiosemicarbazide and acenaphtylene-9,10-quinone to form acenaphtho[1,2-e]-1,2,4-triazine-9(8H)-thiones and subsequent reaction with benzyl chloride derivatives is reported.

Methods

9-(alkylthio) acenaphtho[1,2-e]-1,2,4-triazines were synthesized via the reaction of acenaphtho-9,10-quinone with thiosemicarbazide, and then with the benzyl chloride derivatives. Cytotoxicity of some prepared compounds was assessed through MTT assay on three different human cancerous cell lines (HL-60, MCF7, and MOLT-4 cells). Molecular docking studies were performed via AutoDock4.2 software in order to confirm an apoptosis-inducing activity of acenaphtho scaffolds via the Bcl-2 protein.

Results

Excellent yields of the products, short reaction times and simple work-up are attractive features of this synthetic protocol. The evaluated compounds exhibited moderate to good cytotoxic activities. Docking results on the active site of B-cell lymphoma 2 (Bcl-2) supported the experimental biological data and agreed well with previous in silico data for commonly used anti-cancer drugs. Moreover; results were analyzed considering binding efficiency indices.

Conclusions

The outcomes of the present study may be helpful in future targeting of Bcl-2 with the aim of developing apoptosis-inducing agents.

Synthesis and antiproliferative activity evaluation of imidazole-based indeno[1,2-b]quinoline-9,11-dione derivatives

A series of new imidazole substituted indeno[1,2-b]quinoline-9,11-dione derivatives were synthesized and evaluated for their antiproliferative effects on HeLa, LS180, MCF-7 and Jurkat human cancer cell lines. Antiproliferative effects were evaluated using MTT assay. Prepared compounds exhibited weak to good antiproliferative activity in evaluated cell lines. Prepared compounds were more potent in Jurkat cell line when compared to LS180, HeLa and MCF-7 cell lines. Compounds 29 (IC16 = 0.7 μM) and 31 (IC16 = 1.7 μM) and 33 (IC16 = 1.7 μM) were found to be the most potent molecules on Jurkat cell lines. Moreover; it was found that some of the tested compounds bearing imidazole-2-yl moiety on the C11-position of dihydropyridine ring exhibited superior antiproliferative activity in comparison to cis-platin especially in Jurkat cell line (compounds 29, 31, and 33). It seemed that the introduction of electron-withdrawing groups on the imidazole ring enhanced the antiproliferative potential of these compounds (compounds 27, 29 and 31). The results of this study proposed that some of the imidazole substituted indeno[1,2-b]quinoline-9,11-dione compounds may act as efficient anticancer agents in vitro, emphasizing their potential role as a source for rational design of potent antiproliferative agents.