El-Sayed A. Soliman

Improvement of antioxidant activity of chitosan by chemical treatment and ionizing radiation.

Modification of chitosan (CS) to N-maleoylchitosan (NMCS), N-phthaloylchitosan (NPhCS) and sulfonated-chitosan (SCS) was done using maleic anhydride, phthalic anhydride and chlorosulfonic acid, respectively followed by exposing them to γ-rays at different doses. The molecular weights and structural changes of irradiated chitosan derivatives were determined by GPC, FT-IR and UV-vis spectrophotometer. The molecular weights decreased with increasing irradiation dose. Results revealed that the main polysaccharide structure remained after irradiation. To investigate the enhancement of antioxidant activity of chitosan and its derivatives of different molecular weights, radical mediated lipid peroxidation inhibition, scavenging effect of DPPH radicals, reducing power and ferrous ion chelating activity assays were used. Chitosan derivatives with different molecular weights exhibit antioxidant activity. The lower the molecular weights of chitosan and its derivatives, the higher the antioxidant activity. NMCS possessed high scavenging effect on DPPH radicals compared with NPhCS, SCS and ascorbic acid. The irradiated chitosan and its derivatives could be used as natural antioxidants.

UTILITY OF 1-(2,4-DIMETHOXYPHENYL)-3-ARYL-PROP-2-ENE-1-ONES AS RING TRANSFORMER IN PREPARING HETEROCYCLIC COMPOUNDS AND THEIR POTENTIAL BIOLOGICAL ACTIVITIES

As an effort to synthesize new heterocyclic compounds, which would be expected to have a pharmacological and biological activities, we report here the reactivity of 1-(2,4-dimethoxyphenyl)-3-aryl-2-propen-1-ones (Ia&b), as Michael acceptors under different conditions, towards different Michael donors namely, pyrazolin-5-one, 2-cyanomethylthiazolidin-4-one, thiobarbituric acid, cyclohexanone, and ethyl cyanoacetate affording the adducts bispyrazolo[5,4-b]-4H-pyranes III, 5-oxopyrazolin-4-yl-propan-1-ones IV, 2-(4-oxothiazolidine-2-yl)-5-oxopentano-carbonitrile XI, 4-oxo-4H-pyranol[2,3-d]tetrahydropyrimidin-2-thiones XVI, cyclohexano[b]-4H-pyran XVII, ethyl-5-oxo-pentanoate XVIII, and 1-aroyl-2-arylcyclopropanes XIX respectively. Fusion of XI with excess ammonium acetate yielded 2-aminopyridine derivative XII and 2-aminotetrahydropyridine derivative XIII. Diazotization of XII by treatment with HNO2 at 0°C produced the diazonium chloride derivative XIV which underwent coupling reaction with phenolic compounds to yield the azo-disperse dyes XV. Alkaline hydrolysis of XVIII afforded the corresponding acid XX which reacted with hydrazines by fusion to yield the diazapinone derivatives XXI. The structures of the products obtained were confirmed by elemental analysis, infrared, 1H-NMR, 13C-NMR, and mass spectra. The biological activity for some synthesized products are screened.

A FACILE ONE-POT SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF AZIRIDINES AND THIAZINES FROM 1,3-DIARYLPROP-2-ENONES

Abstract The title compounds 1a,b as examples for acyclic alkenones were utilized for the synthesis of some heterocycles namely, thiazines 2a,b and 3a-d, pyrimidines 4a,b. aziridines 7a,b. The unexpected tribromides 8a,b, obtained from bromination of 1a,b, were readily used to afford the pyrazoles 9a,b and isoxazoles 10 a,b. Biological screening of some selective synthesised compounds was determined in vitro using Gram-negative and Gram-positive bacterial strains.

Synthesis of New Thiadiazoles, 1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazoles, and 1,2,4-Triazolo[2,3-c]quinazoline Derivatives from 3,1-Benzoxazin(4H)-one Derivative

3,1-benzoxazin-4H-one derivative was reacted with Grignard reagents, primary and secondary amines, glycine, hydrazine hydrate, azines, and Schiffs base. The acid hydrazide derivative was the key starting material for the synthesis of triazole, triazolo[3,4-b]thiadiazole, thiadiazole, and triazolo[2,3-c]quinazoline.

Radiation induced crosslinking of polyacrylamide incorporated low molecular weights natural polymers for possible use in the agricultural applications

Superabsorbent hydrogels based on polyacrylamide (PAAm) and Na-alginate (Alg) or chitosan (CS) were synthesized by γ-rays. The effect of dose and copolymer composition on gel content and water absorbency of PAAm/Alg, PAAm/CS and PAAm/Alg/CS hydrogels were studied. The gel content and water absorbency follows the order PAAm/Alg>PAAm/Alg/CS>PAAm/CS. The effect of different cations, fertilizers, buffers on water absorbency of the hydrogels was investigated. Water retention capability of swollen hydrogels as a function of time was studied. PAAm/Alg hydrogel has a high water retention capability. An application of the prepared hydrogels in agricultural fields was performed using maize plants. The results showed that the presence of hydrogels had growth promotion effect on quality and quantity of maize plants. The plants treated by PAAm/Alg hydrogels showed 50% increase in the grain yield suggesting their possible use as a soil conditioner and a water reservoir for plant-soil system.

Spectral Characterization of Novel 3-Phenyl-2-Substituted Quinazoline and Fused Quinazoline Derivatives

Abstract 3-phenyl-2-thioxo-quinazolin-4(3H)one 1 was utilized for the construction of some novel 2-substituted quinazolin-4(3H)one derivatives through the formation of 2-hydrazinyl quinazolinone, which was used as the key starting material for the synthesis of 2-heteryl quinazolines via the reaction with one carbon donors, β-diketones and β-ketoester. Infrared, 1H NMR, and mass spectra of the synthesized compounds were discussed. Some of them showed promising anti-inflammatory activity. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

Synthesis and spectral characterisation of novel 2,3-disubstituted quinazolin-4(3 H )-one derivatives

A new series of 2,3-disubstituted quinazolinones was synthesised via the reaction of readily obtainable 2-thioxo-3-phenylquinazolin-4(3H)-one 1 with ethyl chloroacetate followed by hydrazinolysis to afford the hydrazide 3. This was allowed to react with different electrophilic reagents such as carbon disulfide, phenyl isothiocyanate, β-diketones, anhydrides, acrylonitrile, ethyl cinnamate, aldehydes, arylidene malononitrile and lauroyl chloride. Some of the newly synthesised compounds showed promising anti-inflammatory activities.

Activated Nitriles with Ammonium Benzyldithiocarbamate, Synthesis of Thietane Derivatives

4-Aryl-2-iminothietane-3-carbonitriles 3 were obtained in a moderate yield via the reaction of substituted arylidene malononitriles with ammonium benzyldithio-carbamate. The reaction of 3a with hydrazine hydrate, ethyl carbazate, phenylisothiocyanate, and carbon disulphide have been investigated.

Nano-modification of polyamide thin film composite reverse osmosis membranes by radiation grafting

Abstract Radiation synthesis of reverse osmosis membranes were carried out by grafting of N-Isopropyl acrylamide (NIPAM) and ZnO nanoparticles incorporation onto polyamide thin film composite reverse osmosis membranes PA(TFC). The effect of monomer concentration, radiation time and concentration of ZnO nanoparticles on the grafting percent were investigated. The properties of the prepared grafted reverse osmosis membranes were characterized by using different analytical tools such as contact angles goniometer, Fourier transform IR (FTIR), X-ray diffraction (XRD), Field Emission-Scanning Electron Microscope (FESEM). The performance of the reverse osmosis process of the neat and the modified PA(TFC) membranes in terms of water flux and salt rejection (%) was investigated. The chlorine and biofouling resistance properties of the neat and the modified PA(TFC) membrane were evaluated. It is found that, the performance of the modified ZnO NPs/P(NIPAM)-g-PA(TFC) membrane is much better than the neat PA(TFC) membrane.