Seham Y. Hassan

Synthesis of new series of quinoxaline based MAO-inhibitors and docking studies

A series of 2-benzyl-3-(2-arylidenehydrazinyl)quinoxalines 3, 4-benzyl-1-aryl-[1,2,4]triazolo[4,3-a]quinoxalines 4 and phenyl(1-aryl-[1,2,4]triazolo[4,3-a]quinoxalin-4-yl)methanones 5 analogues were synthesized and investigated for their monoamine oxidase (MAO) inhibitory property. The inhibition profile was found to be competitive for compounds 3k, 3m, 5f and 5n with MAO-A selectivity. Observation of the docked positions of these compounds revealed interactions with many residues previously reported to have an effect on the inhibition of the enzyme. The structural features of the new compounds have been determined from the microanalytical, IR, (1)H, (13)C NMR spectral studies and X-ray crystalography.

Synthesis and biological activity of some new pyrazoline and pyrimidine derivatives

Novas series de pirazolinas, 3-aril-4,5-diidro-1H-pirazol-1-carbaldeidos (4-6), (aril-4,5-diidro1H-pirazol-1-il)etanonas (9-11) e 3-aril-4,5-diidro-1H-pirazois (24 e 25) foram sintetizadas pela reacao de chalconas (1-3) com hidrato de hidrazina em acido formico, acido acetico ou etanol, respectivamente. Novos derivados de pirimidina 6-arilpirimidina-2-amina (32-34) tambem foram sintetizados a partir das mesmas chalconas de partida. As estruturas dos novos compostos sintetizados foram estabelecidas atraves do estudo dos espectros de IV, 1

Antioxidant and Antitumor Activities of New Synthesized Aromatic C-Nucleoside Derivatives

The carbohydrazide 1 was used as the precursor for the synthesis of a number of new aromatic C-nucleosides containing 1,3,4-oxadiazole 7, [1,3,4]oxadiazolo[2,3-a]isoindole 10b and pyrazole units 18. On the other hand, the thiosemicarbazone 20 was used as the key intermediate for synthesis of 1,3,4-oxadiazole and 1,2,4-triazole-3-thione derivatives 21 and 23. The antioxidant activities of the prepared compounds were evaluated. The carbohydrazide 1 in particular was found to have potent antioxidant and antitumor activity.

A regio- and stereo-controlled approach to triazoloquinoxalinyl C-nucleosides

The synthesis of a new series of acyclic triazoloquinoxalinyl C-nucleosides and their transformation to their cyclic analogs are described following protection, activation, and deprotection with subsequent intramolecular nucleophilic substitution protocol. The antibacterial potency of the new compounds was determined using an inhibition zone diameter test. The results show that 3a and 2b exhibit good activity against Escherichiacoli and Candidaalbicans. On the other hand, the cyclic mesylated C-nucleoside 13 showed activity against the Gram-positive bacteria (Staphylococcusaureus) and antifungal activity against C. albicans.

Synthesis and morpholinolysis of N,N-diethyl carbamate derivatives of 4- HOAt, 7-HOAt and HOBt

N,N-Diethyl carbamates of 1-hydroxy-7-azabenzotriazole (7-HOAt), 1-hydroxy-4-azabenzotriazole (4-HOAt), 1-hydroxybenzotriazole (HOBt), and 1-hydroxypyrrolidine-2,5-dione have been synthesised. The reactivities of these active esters have been determined by studying the kinetics and mechanism of their morpholinolysis in acetonitrile at different temperatures.

Synthesis and Bioassay of a New Class of Furanyl-1,3,4-Oxadiazole Derivatives

Tyrosinase enzyme is a monophenol monoxygenase enzyme, which plays an important role in human as a rate limiting step enzyme for different specific metabolic pathways, as well as its useful application in industry and agriculture. So this study was carried out to test the effect of newly prepared compounds containing 1,3,4-oxadiazoles with different substituted groups on tyrosinase enzyme activity, hoping to use them in the treatment of some diseases arising from tyrosinase activity disorders such as Parkinson’s disease, schizophrenia, autism, attention deficit, hyperactivity disorder, and cancer.

5-(5-Aryl-1,3,4-oxadiazole-2-carbonyl)furan-3-carboxylate and new cyclic C-glycoside analogues from carbohydrate precursors with MAO-B, antimicrobial and antifungal activities.

Cyclization of acyclic C-glycoside derivatives 1a,b to 2a,b as the major isomers, and 4a,b as the minor isomers were carried out. The isopropylidene derivatives 3a,b were prepared, as well as the hydrazide derivative 6, which was condensed with a variety of aldehydes to give hydrazones 7a–e which were also prepared from the compounds 12a–e. Acetylation of 7a,d gave the corresponding acetyl derivatives 8a,d, respectively. In addition, the dicarbonyl compound 9 was prepared in the hydrate form, which reacted with a number of aroylhydrazines to give the corresponding bisaroyl-hydrazones 10a–d, which were cyclized into 1,3,4-oxadiazoles 11a–d. Furthermore, two of the prepared compounds were examined to show the ability to activate MAO-B. In addition a number of prepared compounds showed antibacterial and antiviral activities.

Synthesis and Characterization of Glutamic-Chitosan Hydrogel for Copper and Nickel Removal from Wastewater

Chitosan was reacted with four concentrations (2.5, 5, 10 and 20 mmol) of glutamic acid resulting in four types of glutamic-chitosan hydrogels (GCs), the activity of the resulted compounds on the removal of copper(II) and nickel(II) from wastewater were tested. The results indicated that by increasing glutamic acid concentration from GCs-1 to GCs-4, the efficiency of removing Cu(II) and Ni(II) were decreased, which may be due to a decrease in the pore size of the hydrogels as a result of the increased degree of crosslinking.

Synthesis of new 1,3,4-thiadiazole and 1,2,3,4-oxathiadiazole derivatives from carbohydrate precursors and study of their effect on tyrosinase enzyme.

5-(1,2,3,4-Tetrahydroxybutyl)-2-methylfuran-3-carbohydrazide (2) was condensed with a variety of ketones to afford carbohydrazide derivatives 3–6. Acetylation of 3–5 afforded the acetyl derivatives 7–9, while periodate oxidation of 3–6 afforded the formyl derivatives 10–13. Acid catalyzed condensation of thiosemicarbazide or o-tolylthiosemicarbazide with the prepared aldehydes 10–12 gave thiosemicarbazone derivatives 14–19. Cyclization of the latter with acetic anhydride afforded 4,5-dihydro-1,3,4-thiadiazolyl derivatives 20–25. On the other hand, condensation of p-tosylhydrazine with the prepared aldehydes 10–12 afforded p-tosylhydrazone derivatives 26–28. Cyclization of 26–28 with acetic anhydride afforded 1,2,3,4-oxathiadiazole derivatives 29–31 respectively. Moreover, the obtained results regarding to the effect of some of the prepared compounds on tyrosinase enzyme showed that the majority of these compounds having an inhibitory effect; especially compounds 12, 16, 17, and 28.