Abdulrahman M. Al-Obaid

Substituted quinazolines, part 3. Synthesis, in vitro antitumor activity and molecular modeling study of certain 2-thieno-4(3H)-quinazolinone analogs☆

The synthesis of some new 2-thieno-4(3H)-quinazolinone derivatives and their biological evaluation as antitumor agents using the National Cancer Institute (NCI) disease oriented antitumor screen protocol are investigated. Compounds 2-(2-thienylcarbonylamino)-5-iodo-N-(4-hydroxyphenyl)-benzamide (16), 2-(2-thieno)-6-iodo-3-phenylamino-3,4-dihydro-quina-zolin-4-one (26), and 2-(2-thieno)-4-[4-sulfonamidobenzylamino]-6-iodo-quinazoline (42), with GI(50) values of 12.7, 10.3, 16.9 microM, respectively, proved to be the most active members in this study, as compared to the known drug 5-FU. Conformational analysis of the most active molecules using molecular modeling and QSAR techniques enabled the understanding of the pharmacophoric requirements for 2-thieno-quinzolinone derivatives as antitumor agents. These three quinazolinone analogs (16, 26, 42) could be considered as useful templates for future development to obtain more potent antitumor agents.

Methods of analysis of 4-quinolone antibacterials.

A comprehensive review with 270 references for the analysis of the members of an important class of drugs, 4-quinolone antibacterials, is presented. The review covers most of the methods described for the analysis of these drugs either per se, in dosage forms or in biological fluids.

Non-classical antifolates. Part 2: Synthesis, biological evaluation, and molecular modeling study of some new 2,6-substituted-quinazolin-4-ones

A new series of 2,6-substituted-quinazolin-4-ones was designed, synthesized, and evaluated for their in vitro DHFR inhibition, antimicrobial, and antitumor activities. Compounds 22, 33-37, 39-43, and 45 proved to be active DHFR inhibitors with IC(50) range of 0.4-1.0microM. Compound 18 showed broad-spectrum antimicrobial activity comparable to the known antibiotic gentamicin. Compounds 34 and 36 showed antitumor activity at GI(50) (MG-MID) concentrations of 11.2, and 24.2microM, respectively. Molecular modeling study including flexible alignment; electrostatic, hydrophobic mappings; and pharmacophore prediction were performed. A main featured pharmacophore model was developed which justifies the importance of the main pharmacophoric groups as well as of their relative distances. The substitution pattern and spatial considerations of the pi-systems in regard to the quinazoline nucleus proved critical for biological activity.

2,4-disubstituted thiazoles II. A novel class of antitumor agents, synthesis and biological evaluation

Summary A series of 2,4-disubstituted thiazole derivatives bearing N-n-butyl or N-cyclohexylthioureido synthon at position 2 and N-substituted thiosemicarbazone moiety at position 4 have been synthesized and tested for antitumor activity using the National Cancer Institutes in-vitro-disease-oriented antitumor screen. All of the tested compounds showed antineoplastic activity at concentrations less than 100 μM. Compounds 7, 9, 15 and 17 in particular showed activity with GI50 (mean-graph midpoint) of 17.8, 8.5, 9.5 and 7.4 μM, respectively. The detailed syntheses, spectroscopic and biological data are discussed.

5-substituted-2-thiohydantoin analogs as a novel class of antitumor agents.

Certain series of 2-thiohydantoin derivatives, carrying various substituents at position 5 such as 5-bromo-2-thienylmethylene, 5-(2-carboxyphenylthio)-2-thienylmethylene and 2-methylene-4H-thieno[2,3-b][1]benzothiopyran-4-one, were evaluated for their antitumor activity. Compound 5-(5- bromo-2-thienylmethylene)-3-morpholinomethyl-2-(2,3,4,6- tetra-O-acetyl--D-glucopyranosylthio)hydantoin proved to possess a broad spectrum antitumor activity against a wide range of different human cell lines of nine tumor subpanels causing both cytostatic and cytotoxic effects, resulting in full panel median growth inhibition (GI50) and total growth inhibition (TGI), with a median lethal concentration (LC50) at 15.1, 41.7 and 83.2βM, respectively. On the other hand, compound 5-(5-bromo-2-thienylmethylene)-2-thiohydantoin and compound 5-(5-bromo-2-thienylmethylene)-3-phenyl-2- (2,3,4,6-tetra-O-acetyl-bb-D-galactopyranosyl-thio)hydantoin showed potential selectivity against leukemia cell lines. Further derivatization of these compounds, deduced from the obtained tentative structure activity relationships, may lead to more potent agents

Synthesis of novel 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles as potential antimicrobial agents

New series of 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles namely, 2-substitued thio-6-phenyl-3,4-dihydro-4-oxopyrimidine-5-carbonitriles (5a-d, 6, 7a-d, 8), 2-(4-chlorobenzylthio)-4-chloro-6-phenylpyrimidine-5-carbonitrile (9), 2-(4-chlorobenzylthio)-4-arylthio-6-phenylpyrimidine-5-carbonitriles (10a-d) and 2-(4-chlorobenzylthio)-4-arylamino-6-phenylpyrimidine-5-carbonitriles (11a-d) was synthesized and tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 5b, 5c, 6, 7a, 7b, 7c, 9 and 11a displayed marked antibacterial activity particularly against the tested Gram-positive bacteria, while compounds 6, 7c, 7d and 9 were moderately or weakly active against C. albicans.

The voltammetric study and determination of ramipril in dosage forms and biological fluids

The voltammetric behavior of ramipril was studied using cyclic voltammetry, direct current polarography (DCt), differential pulse polarography (DPP) and alternating current polarography (ACt). Ramipril developed well-defined cathodic waves in Britton-Robinson buffers over the pH range 6-12. The waves were characterized as being diffusion-controlled, irreversible and partially affected by adsorption phenomenon. The diffusion-current constant (Id) was 1.24 +/- 0.02. The current-concentration plots were rectilinear over the range 10-50, 4-40 and 0.16-12 micrograms/ml in the DCt, DPP and ACt modes, respectively, with a minimum detectability (S/N = 2) of 0.02 microgram/ml (4.8 x 10(-8) M) using the latter mode. The proposed method was successfully applied to the determination of ramipril in commercial tablets. Hydrochlorothiazide, which is frequently co-formulated with ramipril, did not interfere with the assay. Furthermore, the proposed method was applied to the determination of ramipril in urine and plasma adopting the ACt technique. The percentage recoveries were 97.12 +/- 0.56 and 94.97 +/- 0.62%, respectively. A pathway for the electrode reaction was proposed.

Molecular design, synthesis and biological evaluation of cyclic imides bearing benzenesulfonamide fragment as potential COX-2 inhibitors. Part 2

A group of cyclic imides (1-10) was designed for evaluation as a selective COX-2 inhibitors and investigated in vivo for their anti-inflammatory activity. Compounds 6a, 6b, 8a, 8b, 9a, 9b, 10a and 10b were proved to be potent COX-2 inhibitors with IC50 range of 0.1-4.0 μM. In vitro COX-1/COX-2 inhibition structure-activity studies identified compound 8a as a highly potent (IC50=0.1 μM), and an extremely selective [COX-2 (SI)>1000] comparable to celecoxib [COX-2 (SI)>384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED50=72.4 mg/kg) relative to diclofenac (ED50=114 mg/kg). Molecular modeling was carried out through docking the designed compounds into the COX-2 binding site to predict if these compounds have analogous binding mode to the COX-2 inhibitors. The study showed that the homosulfonamide fragment of 8a inserted deep inside the 2°-pocket of the COX-2 active site, where the SO2NH2 group underwent H-bonding interaction with Gln(192)(2.95 Å), Phe(518)(2.82 Å) and Arg(513)(2.63 and 2.73 Å). Docking study of the synthesized compound 8a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.

SYNTHESIS, CONFORMATIONAL ANALYSIS AND ANTITUMOR TESTING OF 5-(Z)-ARYLIDENE-4-IMIDAZOLIDINONE DERIVATIVES

Abstract A series of 5-(Z)-arylidene-2-amino-4-imidazolidinones 16–34, 5-(Z)-arylidene-2-(2-carboxyphenylamino)-4-imidazolidinones 35–41, 5-(Z)-arylidene-3-aminomethyl-2-thioxo-4-imidazolidinones 42–55 and 5-(Z)-arylidene-3-aminomethyl-2-methylmercapto-4-imidazolidinones 56–67 have been synthesized via two different routes. Conformational analysis and antitumor activities have been studied. The antitumor activity of these compounds showed broad spectrum of activity against a wide range of different human cell lines of nine tumor subpanels causing both cytostatic and cytotoxic potency.

Synthesis and anticancer potential of certain novel 2-oxo-N'-(2-oxoindolin-3-ylidene)-2H-chromene-3-carbohydrazides

Treatment of ethyl 3-hydrazinyl-3-oxopropanoate (6) with indoline-2,3-dione derivatives 7a-g gave ethyl 3-oxo-3-(2-(2-oxoindolin-3-ylidene)hydrazinyl)propanoates 8a-g which were allowed to react with the appropriate salicyaldehyde 9a and/or 9b to furnish the chromene-based hydrazones 10a-i. Compounds 10a-i displayed a significant activity against HT-29 colon cancer cell line and a moderate activity against leukemia K562 cell line. Compound 10f emerged as the most active congener toward HT-29 colon cancer cell line with IC₅₀ = 7.98 ± 0.05 μM whereas compound 10c exhibited the best antiproliferative activity against leukemia K562 cell line with IC₅₀ = 9.44 ± 0.02 μM. Moreover, compound 1e showed 87.81 ± 7% inhibition of side population (SP) HT-29 colon cancer stem cells.