Synthesis and anticoagulant activities of substituted 2,4-diketochromans, biscoumarins, and chromanocoumarins

Controllable Synthesis of Two Isomers 4H-Chromene and 2,8-Dioxabicyclo[3.3.1]nonane Derivatives under Catalyst-Free Conditions

A one-pot method for the selective synthesis of two isomers 4H-chromene and 2,8-dioxabicyclo[3.3.1]nonane derivatives was developed without a catalyst and using EtOH/H₂O (4:1, v/v) as the solvent. The reaction was conducted under mild conditions, with forming multiple chemical bonds in one pot and high atom economy, and only a stoichiometric amount of H₂O is produced as the byproduct. Its selectivity was controlled by thermodynamics and kinetics, and the reasons for the transformation of the two structures are also discussed.

Unveiling the Anti-tubercular Properties of Biscoumarins, through Biological Evaluation and Docking Studies

Background:

Biscoumarin scaffolds are known for their promising pharmacological properties. These compounds have not been studied for their activity against tuberculosis strains.

Objective:

Unveil the antitubercular properties of biscoumarin scaffolds.

Methods:

Biscoumarin derivatives (3a-3l) were synthesized using lemon juice as a catalyst and were investigated for their in-vitro anti-tubercular activity against the H37Rv strain of Mycobacterium tuberculosis using Microplate Alamar Blue Assay Method (MABA). Their binding interaction was investigated by Molecular Docking Studies using InhA with PDB-ID: 2NSD as target receptors in the H37Rv strain of Mycobacterium tuberculosis. These derivatives (3a-3l) were subjected to the neutrophil function test.

Results:

The results revealed that compounds 3b, 3c, 3d, 3f, 3i, 3j showed excellent activity with MIC 1.6μg/mL. Molecular docking interactions for their antitubercular activity proved that the derivatives (3a-3l) can easily bind into the pockets of the enzyme. Neutrophil function test signified that they exhibit moderate neutrophil functions assuring that they do not harm the functioning of Neutrophils.

Conclusion:

These studies have awakened the property of Biscoumarins as promising antitubercular scaffolds.

Lemon Peel Powder: A Natural Catalyst for Multicomponent Synthesis of Coumarin Derivatives

Background:

Lemon peel powder was used as a natural catalyst for the synthesis of biscoumarins and 3,4-dihydropyrano[c]chromene derivatives. The catalyst is natural, biodegradable, environmentally benign and thus contributes a valuable addition to the existing sustainable methods for the synthesis of coumarin derivatives.

Objective:

Development of Green synthesis and use of Natural catalyst.

Methods:

Lemon peel powder was used as a natural, biodegradable, environmentally benign heterogenous catalyst for the synthesis of coumarin derivatives.

Results:

Natural lemon peel powder was successfully used as a heterogeneous catalyst for the synthesis of coumarin based heterocyclic compounds.

Conclusion:

In conclusion, an environmentally benign, green and one-pot multicomponent protocol has been developed for the synthesis of biscoumarins and 3,4-dihydropyrano[c]chromene derivatives using lemon peel powder as a natural and biodegradable catalyst. Lemon peel being natural, the present approach is sustainable and will highlight the emerging applications of natural resources for synthetic organic transformations. This protocol offers several advantages such as high yields, clean reaction conditions, and no pollution threat to the environment making it a useful and attractive process for the synthesis of coumarin derivatives.

Antiestrogenic Activity and Possible Mode of Action of Certain New Nonsteroidal Coumarin-4-acetamides

The preparation of certain 2-(2-oxo-2H-chromen-4-yl)-N-substituted acetamides IIIa-h was planned as a step in the development of new modified nonsteroidal antiestrogens. The purity of target compounds IIIa-h was checked by thin-layer chromatography (TLC), and their structures were confirmed using various spectroscopic tools including IR, 1H-NMR, 13C-NMR, and MS spectroscopy. Viability tests were applied using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay to evaluate the cytotoxic effect of the synthesized compounds against two breast cancer cell lines, MCF-7 and MDA-MB-231. Compound IIIb proved the most active against MCF-7 cells, with an IC50 value of 0.32 μM. The results of an analysis of in vitro antiestrogenic activity indicated that only compound IIIb exhibited antiestrogenic activity; its IC50 value of 29.49 μM was about twice as potent as that of the reference compound, MIBP. The aromatase activity was evaluated for the synthesized target compounds IIIa-g and the intermediates Ib and IIa. A significant aromatase inhibition was observed for the intermediate Ib and compound IIIe, with IC50 values of 14.5 and 17.4 μM, respectively. Compound IIIb, namely 7-methoxy-4-(2-oxo-2-(piperidin-1-yl)ethyl)-2H-chromen-2-one, could be used as an antiestrogen and/or cytotoxic agent with selective activity against tumor cells.

Novel Carbon-based Solid Acid from Green Pistachio Peel as an Efficient Catalyst for the Chemoselective Acylation, Acetalization and Thioacetalization of Aldehydes, Synthesis of Biscoumarins and Antimicrobial Evaluation

Background:

Much attention has been focused on heterogeneous catalysts. Reactions with these recoverable and reusable catalysts are clean, selective with high efficiency. Among the heterogeneous solid acid catalyst in organic synthesis, Carbon-Based Solid Acids (CBSAs), which are important solid acid with many practical and research applications have been extensively studied. In this work, green Pistachio peel, a biomass waste, was converted into a novel carbon-based solid acid catalyst (Pis-SO3H).

Objective:

The aim of this work is to synthesize highly sulfonated carbon as an efficient, recyclable, nontoxic solid acid catalyst by simultaneous sulfonation, dehydration and carbonization of green Pistachio peel as biomass and investigate the catalytic activity of Pis-SO3H in acetalization, thioacetalization, acylation of aldehydes and synthesis of 3,3'-Arylmethylene-bis(4-hydroxycoumarin) derivatives.

Method:

Pis-SO3H was synthesized by an integrated fast one-step hydrothermal carbonization and sulfonation process in the presence of sulfuric acid. The characterization of the physicochemical properties of Pis-SO3H was achieved by XRD, FT-IR, FE-SEM, and elemental analysis.

Results:

The result of acid-base titration showed that the total acidity of the catalyst was 7.75 mmol H+g−1. This new heterogeneous catalyst has been efficiently used for the chemoselective thioacetalization, acetalization and acylation of aldehyde and the synthesis of biscoumarins under solvent-free conditions. All the reactions work easily in high yields. The antimicrobial activity of some of the biscoumarins was evaluated in screening by disk diffusion assay for the zone of inhibition.

Conclusion:

The catalytic activity of the Pis-SO3H was investigated during acetalization, thioacetalization, acylation and synthesis of biscoumarins. The results of protection of carbonyl groups and synthesis of biscoumarins in the present work offer effective alternatives for environmentally friendly utilization of abundant biomass waste.

Development of New Multicomponent Reactions in Eco-Friendly Media-Greener Reaction and Expeditious Synthesis of Novel Bioactive Benzylpyranocoumarins

Multicomponent cyclocondensation of hydrazine derivatives, ethyl acetoacetate, aromatic aldehydes, and 4-hydroxycoumarin has been reported. The optimization details of the developed novel protocol are recorded. The novel procedure features short reaction time, moderate yields, and simple workup. In addition, BMIM[triflate] was chosen as a green solvent. The structures of the obtained benzylpyrazolyl coumarins were determined and confirmed by 1H NMR, 13C NMR, IR, and elemental analysis. The MIC values of benzylpyrazolyl coumarin derivatives were determined by the microbroth dilution method using 96-well plates. However, the derivatives 5a, 5b, 5d, and 5g possess the strongest activities. Compound 5b was the most active derivative against Candida albicans. Moreover, the antioxidant activity determination of these coumarins derivatives 5(a–g)–6(a–g) were studied with the DPPH and compared with gallic acid (GA)and butylated hydroxytoluene (BHT). Molecular modelling studies using DFT (density functional theory) calculations showed that there two tautomers A and B in which A is more stable than B. The benzylpyrazolyl coumarin derivatives 5e and 6f exhibited the most cytotoxic effect on the promising cytotoxic activity with IC50 values 4.45 μg/mL against MDA-MB-231 and 4.85 μg/mL against MCF7, respectively.

Synthesis and characterization of a magnetic graphene oxide/Zn–Ni–Fe layered double hydroxide nanocomposite: an efficient mesoporous catalyst for the green preparation of biscoumarins

A novel magnetic graphene oxide/Zn–Ni–Fe-layered double hydroxide was prepared and then utilized as an efficient heterogeneous as well mesoporous catalyst towards the synthesis of biscoumarin materials.

Development of pyridine dicoumarols as potent anti HIV-1 leads, targeting HIV-1 associated topoisomeraseIIβ kinase

Aim: A structural study of a series of pyridine dicoumarol derivatives with potential activity against a novel Topoisomerase IIβ kinase which was identified in the HIV-1 viral lysate, compounds were designed and synthesized based on a 3D-QSAR study. Materials & methods: Based on QSAR model we have designed and synthesized a series of pyridine dicoumarol derivatives and characterized by spectral studies, all the molecules are biologically evaluated by kinase assay, cytotoxicity assay, ELISA and PCR method. Result: We demonstrated the achievement of water soluble disodium pyridine dicoumarate derivatives showing high anti-HIV-1 activity (IC50 <25 nM) which provides a crucial point for further development of pyridine dicoumarol series as HIV-1-associated topoisomerase IIβ kinase inhibitors for clinical application against AIDS. Conclusion: A new class of anti-HIV-1 lead compounds have been designed and tested. Further studies would result in development of  novel and potential drugs.

Friedel–Crafts alkylation of 4-hydroxycoumarin over silica-bonded 1,4-diaza-bicyclo[2.2.2] octane-sulfonic acid chloride as nanostructured heterogeneous catalyst

A novel nanostructured heterogeneous catalyst, namely silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride (SBDBSAC), has been synthesized and fully characterized by several techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), scanning electron microscope (SEM), and energy dispersive X-ray analysis (EDX). Afterward, the nanostructured catalyst was utilized as an efficient catalyst for the synthesis of bis-coumarin derivatives by the condensation reaction of arylaldehydes with 4-hydroxycoumarin at 70 °C under solvent-free conditions.

Dicoumarol complexes of Cu(II) based on 1,10-phenanthroline: synthesis, X-ray diffraction studies, thermal behavior and biological evaluation

A series of Cu(II) complexes containing dicoumarol derivatives and 1, 10-phenanthroline have been synthesized. Structural and spectroscopic properties of ligands were studied on the basis of mass spectra, NMR ((1)H and (13)C) spectra, FT-IR spectrophotometry and elemental analysis, while physico-chemical, spectroscopic and thermal properties of mixed ligand complexes have been studied on the basis of infrared spectra, mass spectra, electronic spectra, powder X-ray diffraction, elemental analysis and thermogravimetric analysis. X-ray diffraction study suggested the suitable octahedral geometry for hexa-coordinated state. The kinetic parameters such as order of reaction (n), energy of activation (Ea), entropy (S(*)), pre-exponential factor (A), enthalpy (H(*)) and Gibbs free energy (G(*)) have been calculated using Freeman-Carroll method. Ferric-reducing antioxidant power (FRAP) of all complexes were measured. All the compounds were screened for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Streptococcus pyogenes and Bacillus subtilis, while antifungal activity against Candida albicans and Aspergillus niger have been carried out. Also compounds against Mycobacterium tuberculosis shows clear enhancement in the anti-tubercular activity upon copper complexation.