Assem Barakat

Zwitterionic pyrimidinium adducts as antioxidants with therapeutic potential as nitric oxide scavenger

A variety of zwitterionic adducts were synthesized by using means green chemistry method. The products contain the biologically active barbituric acid moiety embedded in zwitterion products. Both features are pharmaceutically relevant. The chemical structures were deduced by (1)H-, (13)C-, NMR and HRMS spectral analysis, and X-ray diffraction techniques. In vitro evaluation for the antioxidant activities were carried out towards the inhibition of nitric oxide (NO) radical, known to regulate a mechanism of signals for various cellular functions. NO also play an important role as a mediator of various pathological conditions responsible for cellular damages such as strokes, cancers, diabetes, chronic heart failure and inflammatory disease and various neurodegenerative disorders. All tested compounds were found to be more potent nitric oxide scavengers as compared to standard drug ascorbic acid (IC50 = 618 ± 2.0 μM). Compounds 4c and e exhibiting several hundred fold more activity against nitric oxide radical with IC50 values of 69 ± 1.66 and 70.1 ± 0.89 μM respectively, as compared to standard drug ascorbic acid (IC50 = 618 ± 2.0 μM).

Tandem Aldol-Michael Reactions in Aqueous Diethylamine Medium: A Greener and Efficient Approach to Bis-Pyrimidine Derivatives

A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%).

Synthesis, reactions and biological activity of some new bis-heterocyclic ring compounds containing sulphur atom

BackgroundThe derivatives of thieno[2,3-b]thiophene belong to a significant category of heterocyclic compounds, which have shown a wide spectrum of medical and industrial application.ResultsA new building block with two electrophilic center of thieno[2,3-b]thiophene derivatives 2 has been reported by one-pot reaction of diketone derivative 1 with Br2/AcOH in excellent yield. A variety of heteroaromatics having bis(1H-imidazo[1,2a] benzimidazole), bis(1H-imidazo[1,2-b][1,2,4]triazole)-3-methyl-4-phenylthieno[2,3-b]thiophene derivatives, dioxazolo-, dithiazolo-, and 1H-imidazolo-3-methyl-4-phenylthieno[2,3-b]thiophene derivatives as well pyrrolo, thiazolo -3-methyl-4-phenylthieno[2,3-b]thiophene derivatives have been designed, synthesized, characterized, and evaluated for their biological activity. Compounds 3–9 showed good bioassay result. These new derivatives were evaluated for anti-cancer activity against PC-3 cell lines, in vitro antioxidant potential and β-glucuronidase and α-glucosidase inhibitory activities. Compound 3 (IC50 = 56.26 ± 3.18 μM) showed a potent DPPH radical scavenging antioxidant activity and found to be more active than standard N-acetylcystein (IC50 = 105.9 ± 1.1 μM). Compounds 8a (IC50 = 13.2 ± 0.34 μM) and 8b (IC50 = 14.1 ± 0.28 μM) found as potent inhibitor of α-glucusidase several fold more active than the standard acarbose (IC50 = 841 ± 1.73 μM). Most promising results were obtained in β-glucuronidase enzyme inhibition assay. Compounds 5 (IC50 = 0.13 ± 0.019 μM), 6 (IC50 = 19.9 ± 0.285 μM), 8a (IC50 = 1.2 ± 0.0785 μM) and 9 (IC50 = 0.003 ± 0.09 μM) showed a potent inhibition of β-glucuronidase. Compound 9 was found to be several hundred fold more active than standard D-Saccharic acid 1,4-lactone (IC50 = 45.75 ± 2.16 μM).ConclusionsSynthesis, characterization, and in vitro biological activity of a series of thieno[2,3-b]thiophene have been investigated.

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM).

An efficient and green procedure for synthesis of rhodanine derivatives by aldol-thia-Michael protocol using aqueous diethylamine medium

A simple, economical, and green approach to the synthesis of rhodanine derivatives using a tandem aldol condensation-thia-Michael addition process in aqueous diethylamine medium was described. The experiment protocol features simple operations, and the products were isolated in high to excellent yields (82–96%). As spontaneous precipitation always occurs at the end of the process, this leads to easy separation of the products via a simple filtration.

Synthesis, in vitro biological activities and in silico study of dihydropyrimidines derivatives

We describe here the synthesis of dihydropyrimidines derivatives 3a-p, and evaluation of their α-glucosidase enzyme inhibition activities. Compounds 3b (IC50=62.4±1.5 μM), 3c (IC50=25.3±1.26 μM), 3d (IC50=12.4±0.15 μM), 3e (IC50=22.9±0.25 μM), 3g (IC50=23.8±0.17 μM), 3h (IC50=163.3±5.1 μM), 3i (IC50=30.6±0.6 μM), 3m (IC50=26.4±0.34 μM), and 3o (IC50=136.1±6.63 μM) were found to be potent α-glucosidase inhibitors in comparison to the standard drug acarbose (IC50=840±1.73 μM). The compounds were also evaluated for their in vitro cytotoxic activity against PC-3, HeLa, and MCF-3 cancer cell lines, and 3T3 mouse fibroblast cell line. All compounds were found to be non cytotoxic, except compounds 3f and 3m (IC50=17.79±0.66-20.44±0.30 μM), which showed a weak cytotoxic activity against the HeLa, and 3T3 cell lines. In molecular docking simulation study, all the compounds were docked into the active site of the predicted homology model of α-glucosidase enzyme. From the docking result, it was observed that most of the synthesized compounds showed interaction through carbonyl oxygen atom and polar phenyl ring with active site residues of the enzyme.

Synthesis of Thieno[2,3-b]thiophene Containing Bis-Heterocycles-Novel Pharmacophores

Thioenethiophene derivatives represent an important class of compounds with diverse biological activities. We describe here the synthesis of a new series of thieno[2,3-b]thiophene containing bis-heterocyclic compounds 3–7. All the compounds were evaluated for their in vitro antioxidant potential, α-glucosidase and β-glucuronidase inhibiton and anticancer activity against PC-3 cell lines. Compounds 2b (IC50 = 1.3 ± 0.2 μM), 5a (IC50 = 2.3 ± 0.4 μM) and 5b (IC50 = 8.7 ± 0.1 μM) showed a potent inhibition of β-glucuronidase enzyme, more active than the standard d-saccharic acid 1,4-lactone (IC50 = 45.8 ± 2.5 μM). Compounds 5a (IC50 = 22.0 ± 0.3 μM) and 5b (IC50 = 58.4 ± 1.2 μM) were also found to be potent α-glucosidase inhibitors as compared to standard drug (acarbose, IC50 = 841 ± 1.7 μM).

1,1'-(3-methyl-4-phenylthieno[2,3-b]thiophene-2,5-diyl)diethanone as a building block in heterocyclic synthesis. Novel synthesis of some pyrazole and pyrimidine derivatives.

A series of new bis(heterocycles) featuring thieno[2,3-b]thiophene rings was synthesized in a combinatorial manner. Intramolecular cyclization of enaminone derivativeswith appropriate N-nucleophiles afforded the target compounds. All compounds were characterized by 1H-, 13C-NMR, GCMS, IR, and UV-Vis spectrometry. These compounds represent a new class of sulfur- and nitrogen-containing heterocycles that should also be of interest as new materials.

A Greener, Efficient Approach to Michael Addition of Barbituric Acid to Nitroalkene in Aqueous Diethylamine Medium

An efficient method for the synthesis of a variety of pyrimidine derivatives 3a–t by reaction of barbituric acids 1a,b as Michael donor with nitroalkenes 2a–k as Michael acceptor using an aqueous medium and diethylamine is described. This 1,4-addition strategy offers several advantages, such as using an economic and environmentally benign reaction media, high yields, versatility, and shorter reaction times. The synthesized compounds were identified by 1H-NMR, 13C-NMR, CHN, IR, and MS. The structure of compound 3a was further confirmed by single crystal X-ray structure determination.

Synthesis of pyrimidine-2,4,6-trione derivatives: Anti-oxidant, anti-cancer, α-glucosidase, β-glucuronidase inhibition and their molecular docking studies.

This paper describes a facile protocol, efficient, and environmentally benign for the synthesis a series of barbiturate acid substituted at C5 position 3a-o. The desired compounds subjected in vitro for different set of bioassays including against anti-oxidant (DPPH and super oxide scavenger assays), anti-cancer, α-glucosidase and β-glucuronidase inhibitions. Compound 3m (IC50=22.9±0.5μM) found to be potent α-glucosidase enzyme inhibitors and showed more activity than standard acarbose (IC50=841±1.73μM). Compound 3f (IC50=86.9±4.33μM) found to be moderate β-Glucuronidase enzyme inhibitors and showed activity comparatively less than the standard d-saccharic acid 1,4-lactone (IC50=45.75±2.16μM). Furthermore, in sillico investigation was carried out to investigate bonding mode of barbiturate acid derivatives.