Omar M. Ali

Insertion of 5-methyl-N4-(1-pyrenylmethyl)cytidine into DNA. Duplex, three-way junction and triplex stabilities

Abstract 5′- O -(4,4′-dimethoxytrityl)-5-methyl- N 4 -(1-pyrenylmethyl)cytidine( 5 ) was prepared by reaction of 1-pyrenylmethylamine with an appropriate protected 4-(1,2,4-triazolyl)thymidine derivative which was synthesized from 5- O -DMT protected thymidine by acetylation with acetic anhydride and subsequent reaction with triethylamine, 1,2,4-triazole and POCl 3 . Stabilities are reported for DNA duplexes, three-way junctions and triplexes when 5 is inserted. Most interestingly, the three-way junctions are stabilized when 5 is used for insertion into the junction region. This break-through for recognizing the foot of a stem could have far-reaching importance because new targets for antisense oligos is now rendered possible on intact secondary structures.

Anti-HIV Activity of New Substituted 1,3,4-Oxadiazole Derivatives and their Acyclic Nucleoside Analogues

A number of new 5-[(naphthalen-5-yloxy)methyl]-1,3,4-oxadiazole derivatives, 2 - 5 and 8 - 11, were synthesized. The 2-{5-[(naphthalen-5-yloxy)methyl]-1,3,4-oxadiazol-2-ylthio}acetohydrazones 6a and 6b were synthesized by the reaction of the hydrazide 4 with the corresponding monosaccharides. Cyclization of the sugar hydrazones 6a and 6b with acetic anhydride afforded the substituted oxadiazoline derivatives 7a and 7b. The synthesized compounds were evaluated for their antiviral activity against, the human immunodefi ciency virus (HIV-1) and some of these compounds showed moderate to high antiviral activity.

Synthesis of N4-β-D-glycoside cytosines and sugar N4-acetylcytosin-1-ylmethylhydrazones as antiviral agents

Reaction of monosaccharide aldoses with cytosine (1) gave stereoselectively β-N-glycosides 2a–d, which were treated with acetic anhydride in pyridine to afford the corresponding acetylated derivatives 3a–d. N4-Acetylcytosine (4) was synthesised and treated with ethyl chloroacetate to give 1-(ethoxycarbonylmethyl)-N4-acetylcytosine (5). Hydrolysis of the latter ester with hydrazine hydrate afforded the hydrazide derivative 6. Condensation of the hydrazide with monosaccharide aldoses gave the corresponding sugar hydrazones 7a–f. Acetylation of the hydrazones afforded the per-O-acetyl derivatives 8a–f. The prepared compounds were tested for antiviral activity against hepatitis B virus (HBV) which showed moderate activities.

Synthesis and antimicrobial activity of new substituted 1,2,4-triazoles and their acyclic C-nucleoside analogues.

A number of new substituted 1,2,4-triazole {[(1,2,4-triazolyl)ethyl]tetrazolyl} derivatives, their sugar hydrazones, and their acyclic C-nucleoside analogues were synthesized and tested for their antimicrobial activity against Bacillus subtilis (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Streptomyces species (Actinomycetes). The synthesized compounds displayed different degrees of antimicrobial activities or inhibitory actions.

Three Component Synthesis of New (1,3,4-Thiadiazolamino)Methylphosphonates, Their Glycoside and Oxygenated Alkylthio Analogs

Abstract A number of (1,3,4-thiadiazol-2-ylamino)methylphosphonate derivatives were synthesized in a three component reaction. The thioglycoside derivatives and oxygenated alkylthio analogs were also prepared by reaction with halo sugars or different acyclic oxygenated alkyl halides. GRAPHICAL ABSTRACT

Synthesis and antimicrobial activity of new substituted fused 1,2,4-triazole derivatives.

A number of new substituted 1,2,4-triazole, 1,2,4-triazolo[3,4-b]1,3,4-thiadiazole and 1,2,4-triazolo[3,4-b]1,3,4-thiadiazine derivatives were synthesized and tested for their antimicrobial activity against Bacillus subtilis (Gram-positive), Pseudomonas aeruginosa (Gramnegative), and Streptomyces species (Actinomycetes). The synthesized compounds displayed different degrees of antimicrobial activities or inhibitory actions.

Preparation, spectroscopic, and biological characterizations of novel and #945;-aminophosphonates bearing paracetamol

Background: α-Aminophosphonate derivatives have an important biological activity against bacteria, fungi, and anticancer activity. n nAims and Objectives: This study aims to study preparation, spectroscopic, and biological characterizations of novel α-aminophosphonates bearing paracetamol. n nMaterials and Methods: A series of α-aminophosphonate analogs and arylidene derivatives were synthesized, monitored by thin-layer chromatography, purified by chromatographic methods, and the structures were elucidated by spectroscopic methods such as H nuclear magnetic resonance. The synthesized compounds were tested for their antibacterial activity by hole well method against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), the antibacterial activity was evaluated based on inhibition zone size around dishes against Gram-positive. n nResults: Compounds 7e, 8a, 7c, 8b, and 8g are showed different degree of inhibitory effect against S. aureus; on the other hand in Gram-negative, the compounds 7a, 7c, 7d, 7e, 8a, 8b, and 8g are showed different degree of inhibitory effect against E. coli. In this study, we concluded that the results showed that increasing the zone inhibition in compared with amoxicillin and tetracycline against E. coli and S. aureus. Most of the compounds tested against microbes showed a moderate to high effect while few compounds showed a low antimicrobial effect. n nConclusion: In this study, we recommended that α-aminophosphonate and arylidene derivatives used as antimicrobial agents.