Taha M. A. Eldebss

Synthesis, spectral characterization, solution equilibria, in vitro antibacterial and cytotoxic activities of Cu(II), Ni(II), Mn(II), Co(II) and Zn(II) complexes with Schiff base derived from 5-bromosalicylaldehyde and 2-aminomethylthiophene.

Schiff base namely 2-aminomethylthiophenyl-4-bromosalicylaldehyde (ATS)(4-bromo-2-(thiophen-2-yl-imino)methylphenol) and its metal complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, ESR and thermal analysis (TGA). The analytical data of the complexes show the formation of 1:2 [M:L] ratio of the formula [ML2], where M represents Ni(II), Zn(II) and Cu(II) ions, while L represents the deprotonated Schiff base. IR spectra show that ATS is coordinated to the metal ions in a bidentate manner through azomethine-N and phenolic-oxygen groups. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria. A cytotoxicity of the compounds against colon (HCT116) and larynx (HEP2) cancer cells have been studied. Protonation constants of (ATS) ligand and stability constants of its Cu2+, Co2+, Mn2+, Zn2+ and Ni2+ complexes were determined by potentiometric titration method in 50% (v/v) DMSO-water solution at ionic strength of 0.1 M NaNO3.

Design, synthesis and structure-activity relationship study of novel pyrazole-based heterocycles as potential antitumor agents.

The versatile hitherto unreported 3-[(E)-3-(dimethylamino)acryloyl]-1,5-diphenyl-1H-pyrazole-4-carbonitrile (3) was prepared via the reaction of 3-acetyl-1,5-diphenyl-1H-pyrazole-4-carbonitrile (1) with dimethylformamid-dimethylacetal (DMF-DMA). The latter product and 3-((E)-3-morpholin-4-yl-acryloyl)-1,5-diphenyl-1H-pyrazole-4-carbonitrile (4) underwent regioselective 1,3-dipolar cycloaddition with nitrilimines to afford the corresponding pyrazole derivatives. In vivo anti-estrogenic activity and acute toxicity after single oral dose of the newly synthesized compounds were evaluated. In vitro disease-oriented primary antitumor screening utilizing 14 cell lines of breast and ovarian tumor subpanels has been also carried out. All tested compounds showed anti-estrogenic properties equipotent or superior to the reference drug, letrozole. 3-[3-(4-Cyano-1,5-diphenyl-1H-pyrazole-3-yl)-1-(4-methylphenyl)-1H-pyrazole-4-carbonyl]-1,5-diphenyl-1H-pyrazole-4-carbonitrile (27c) and 3-(3-acetyl-1-phenyl-1H-pyrazole-4-carbonyl)-1,5-diphenyl-1H-pyrazole-4-carbonitrile (8a) showed a significant cytotoxic activity in a nanomolar range against certain types of breast and ovarian tumors with tolerable toxicity.

Synthesis and Structure-activity Relationship Studies of Pyrazole-based Heterocycles as Antitumor Agents

Several 4‐cyano‐1,5‐diphenylpyrazoles attached to different heterocyclic ring systems at position 3 were synthesized starting from ethyl 4‐cyano‐1,5‐diphenyl‐1H‐pyrazole‐3‐carboxylate 1. The newly synthesized compounds were tested in vivo for their anti‐estrogenic effects and evaluated in vitro for their cytotoxic properties against estrogen‐dependent tumors. 3‐(5‐Mercapto‐1,3,4‐oxadiazole‐2‐yl)‐1,5‐diphenyl‐1H‐pyrazole‐4‐carbonitrile 13 revealed the highest cytotoxic activity with a GI50 value equal to 40 nM against the IGROVI ovarian tumor cell line. It also showed an anti‐estrogen activity 1.6 more effective than the reference drug, in addition to a high tolerable dose. 3‐(5‐(Methylthio)‐4‐phenyl‐4H‐1,2,4‐triazol‐3‐yl)‐1,5‐diphenyl‐1H‐pyrazole‐4‐carbonitrile 7 was found to have the highest anti‐estrogenic activity, while 1,5‐diphenyl‐3‐[5‐(phenylamino)‐1,3,4‐thiadiazol‐2‐yl]‐1H‐pyrazole‐4‐carbonitrile 11 showed the lowest activity. The oral LD50 values revealed that most of the tested compounds are relatively nontoxic.

Ultrasound assisted one-pot, three-components synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines: A new access via phenylsulfone synthon.

A simple, facile, efficient and three-components procedure for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines utilizing phenylsulfone synthon, under ultrasonic irradiation was developed.

Diphenylpyrroles: Novel p53 activators.

Cellular tumor antigen p53 is crucial for cancer prevention via different mechanisms. E3 ubiquitin-protein ligase HDM2 binds to p53, blocks its ability to activate transcription, and therefore acts as a negative regulator. Blocking p53 binding site on HDM2 was believed to generate efficient antitumor agents. So far, limited scaffolds were reported with HDM2 antagonist activity. Herein, diphenylpyrroles were introduced and evaluated as a novel scaffold in the field of p53 activators. An efficient synthesis of novel 3-heteroaryl-pyrroles is described via reactions of E-3-(dimethylamino)-1-(2-methyl-4,5-diphenyl-1H-pyrrol-3-yl)prop-2-en-1-one or E-1-(2-methyl-4,5-diphenyl-1H-pyrrol-3-yl)-3-morpholinoprop-2-en-1-one with hydrazine hydrate, phenyl hydrazine, hydroxylamine, various heterocyclic amines and active methylene compounds.

Novel 4-heteroaryl-antipyrines as DPP-IV inhibitors.

Type 2 diabetes mellitus is a vast growing progressive disease that almost affects one person among every twelve globally. Regardless the availability of wide variety of oral hypoglycemics, only one‐third of patients achieves proper glycemic control. With the advantage of the low risk of hypoglycemia, DPP‐IV attracted the attention of medicinal chemists as a new target for oral hypoglycemics. In this report, a lead compound 1, with antipyrine scaffold, was obtained, and its binding mode was calculated. Several derivatives with bridged nitrogenous heterocycles have been synthesized via multicomponent reaction under controlled microwave heating conditions. The antidiabetic activity versus DPP‐IV protein was evaluated and compared with sitagliptin. Compounds with smaller‐ or medium‐sized nitrogenous bridges were comparable with sitagliptin in terms of DPP‐IV inhibitory activity, potentially via targeting Glu203 and Glu204. The oral hypoglycemic activities of compounds with submicromolar IC50 values were further evaluated using diabetic mouse model.

A convenient synthesis of pyrazole-substituted heterocycles

(E)-1-(5-Methyl-1-phenylpyrazol-4-yl)-3-(N,N-dimethylamino)-2-propen-1-one reacts with hydrazine, hydroxylamine, guanidine and aminopyrazole derivatives to afford the corresponding 3,4′-bipyrazole, pyrazolylisoxazole, pyrazolylpyrimidine and pyrazolo[1,5-a]pyrimidine derivatives, respectively. It reacts also with benzoquinone, naphthoquinone and N-benzoylglycine to give the corresponding benzofuran and pyrazolylpyranone derivatives, respectively.

Synthesis and antiviral activity of some new bis-1,3-thiazole derivatives

Treatment of 3-phenyl-1,3-thiazolidin-4-one derivative 1 with phenylisothiocyanate in DMF, in the presence of potassium hydroxide, at room temperature gave the non-isolable potassium salt 2. The in-situ reaction of 2 with differently substituted N-aryl hydrazonoyl chlorides 3, 7a-d and 14a-d afforded the corresponding 2-(pyrazolyl)thiazolylimino-5-(thiadiazolylidene)thiazolidin-4-one derivatives 6, 10a-d and 17a-d, respectively. Reaction of 2 with further α-haloketones yielded the 4-(pyrazolyl)thiazolylimino-bis-thiazolidine derivatives 22, 25 and 26. Single crystal X-ray analysis was used in structure elucidation of the products. The in-vitro antiviral screening against four viruses (Poliovirus, Influenza A (H1N1) virus, Hepatitis B virus and Hepatitis C virus) for the obtained compounds was examined. Structure activity relationship (SAR) was also studied. The goal of the work was achieved in discovering a very active compound 10a as anti HCV agent (EC50 0.56 μM).

Novel Benzo[d]imidazole-based Heterocycles as Broad Spectrum Anti-viral Agents: Design, Synthesis and Exploration of Molecular Basis of Action

The design and synthesis of a novel series of benzo[d]imidazole-based heterocycles and their biological evaluation as antiviral agents are reported herein. 1-(1-Methyl-1H-benzo[d]imidazol- 2-yl)-2-thiocyanatoethanone 2 was used as a key intermediate for the synthesis of the thiazolylhydrazine 4, the thiazolylamine 5 and the methylthiazole 7. Coupling of compounds 5 or 7 with the appropriate diazotized aromatic amines gave the diazenyl derivatives 6a-c and 8a-c, respectively. The quinazoline derivative 12 was also synthesized. On the other hand, the phenylthio 20 and the phenylsulphonyl 22 bioisosteresand their respective diazenyl derivatives 21a-c and 23a-c were prepared. The synthesized compounds were evaluated for their HIV-1, HCV, SSPE and H1N1 inhibitory activities and were found to display very promising results. Furthermore, to investigate the underlying possible mechanism of action, in vitro and in silico screening of this series of benzo[d]imidazoles was performed against the viral enzymes HIV-1 RT, HCV NS3/4A serine protease and H1N1 NA1. Overall findings of the executed investigations highlight these novel compounds as very promising potent, broad spectrum antiviral agents.

Novel pyrrole derivatives as selective CHK1 inhibitors: design, regioselective synthesis and molecular modeling

An efficient synthesis of hitherto unreported 3-heteroaryl-pyrroles was described via regioselective 1,3-dipolar cycloaddition reactions of enaminone2 or 3 with nitrilimines 5a–j to afford the corresponding pyrazole derivatives 7a–j. Hydrazinolysis of 7a–f yielded the respective pyrazolo[3,4-d]pyridazines 10a–f. Furthermore, pyrrole analogs substituted on the 3-position with pyranone (14), benzofuran (16) or naphthofuran (18) were also synthesized. The structures of the synthesized compounds were determined by spectral, elemental analyses and alternative syntheses wherever possible. The synthesized compounds were evaluated for their protein kinase inhibitory activities against 25 kinases belonging to 4 kinase groups viz. AGC (5 kinases), CAMK (5 kinases), CMGC (4 kinases) and TK (11 kinases). While the tested compounds were found to be good inhibitors of VEGFR-2 and EGFR, exhibiting low micromolar IC50 values, they were selectively more potent against CHK1 eliciting a potent inhibitory effect with IC50 values in the submicromolar range. Finally, docking studies were performed to interpret the possible binding mode of the target compounds with CHK1.