Mohammed A. Khedr

99mTc-amitrole as a novel selective imaging probe for solid tumor: In silico and preclinical pharmacological study

Lactoperoxidase (LPO) inhibitors are very selective for solid tumor due to their high binding affinity to the LPO enzyme. A computational study was used to select top-ranked LPO inhibitor (alone and in complex with (99m)Tc) with high in silico affinity. The novel prepared (99m)Tc-amitrole complex demonstrated both in silico and in vivo high affinity toward solid tumors.(99m)Tc-amitrole was radio-synthesized with a high radiochemical yield (89.7±3.25). It showed in vitro stability for up to 6h. Its preclinical evaluation in solid tumor-bearing mice showed high retention and biological accumulation in solid tumor cells with a high Target/Non-Target (T/NT) ratio equal to 4.9 at 60min post-injection. The data described previously could recommend (99m)Tc-amitrole as potential targeting scintigraphic probe for solid tumor imaging.

New Coumarin Derivatives as Potent Selective COX-2 Inhibitors: Synthesis, Anti-Inflammatory, QSAR, and Molecular Modeling Studies.

Two new series of coumarin derivatives incorporating thiazoline and thiazolidinone moieties were designed, synthesized, and investigated in vivo for their anti‐inflammatory activities using the carrageenan‐induced rat paw edema model and in vitro for their inhibitory activities against the human cyclooxygenase (COX)‐1 and COX‐2 isoforms. Most of the synthesized compounds demonstrated exceptionally high in vivo anti‐inflammatory activity and displayed superior GI safety profiles (0–7% ulceration) as compared to indomethacin. All the bioactive compounds showed in vitro high affinity and selectivity toward the COX‐2 isoenzyme, compared to the reference celecoxib with IC50 values ranging from 0.31 to 0.78 μM. The ethyl thiosemicarbazone 2b, thiazoline derivatives 3a, 3b, 5b, 6a, and 7f, and the thiazolidinone compounds 8b and 9a showed the highest in vivo and in vitro anti‐inflammatory activities with remarkable COX‐2 selectivity. Quantitative structure–activity relationship study (QSAR) was done and resulted in a highly predictive power R2 (0.908). A molecular docking study revealed a relationship between the docking affinity and the biological results.

Synthesis, Characterization and Molecular Docking of Novel Bioactive Thiazolyl-Thiazole Derivatives as Promising Cytotoxic Antitumor Drug

Reactions of ethylidenethiocarbohydrazide with hydrazonoyl halides gave 1,3-thiazole or 1,3,4-thiadiazole derivatives according to the type of hydrazonoyl halides. Treatment of ethylidenethiosemicarbazide with hydrazonoyl halides and dimethylacetylene dicarboxylate (DMAD) afforded the corresponding arylazothiazoles and 1,3-thiazolidin-4-one derivatives, respectively. The structures of the synthesized products were confirmed by IR, 1H-NMR, 13C-NMR and mass spectral techniques. The cytotoxic activity of the selected products against the Hepatic carcinoma cell line (Hepg-2) was determined by MTT assay indicating a concentration dependent cellular growth inhibitory effect, especially for compounds 14c and 14e. The dose response curves indicated the IC50 (the concentration of test compounds required to kill 50% of cell population) were 0.54 μM and 0.50 μM, respectively. Confocal laser scanning imaging of the treated cells stained by Rhodamin 123 and Acridine orange dyes confirmed that the selected compounds inhibit the mitochondrial lactate dehydrogenase enzymes. The binding mode of the active compounds was interpreted by a molecular docking study. The obtained results revealed promising cytotoxic activity.

Design, synthesis, assessment, and molecular docking of novel pyrrolopyrimidine (7-deazapurine) derivatives as non-nucleoside hepatitis C virus NS5B polymerase inhibitors.

Hepatitis C virus (HCV) infection is highly persistent and presents an unmet medical need requiring more effective treatment options. This has spurred intensive efforts to discover novel anti-HCV agents. The RNA-dependent RNA polymerase (RdRp), NS5B of HCV, constitutes a selective target for drug discovery due to its absence in human cells; also, it is the centerpiece for viral replication. Here, we synthesized novel pyrrole, pyrrolo[2,3-d]pyrimidine and pyrrolo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidine derivatives. The non-toxic doses of these compounds on Huh 7.5 cell line were determined and their antiviral activity against HCVcc genotype 4a was examined. Compounds 7j, 7f, 5c, 12i and 12f showed significant anti HCV activity. The percent of reduction for the non-toxic doses of 7j, 7f, 5c, 12i and 12f were 90%, 76.7±5.8%, 73.3±5.8%, 70% and 63.3±5.8%, respectively. The activity of these compounds was interpreted by molecular docking against HCV NS5B polymerase enzyme.

Design, synthesis, and computational studies on dihydropyrimidine scaffolds as potential lipoxygenase inhibitors and cancer chemopreventive agents

Dihydropyrimidine scaffold has a wide range of potential pharmacological activities such as antiviral, antitubercular, antimalarial, anti-inflammatory, and anticancer properties. 5-Lipoxygenase enzyme is an enzyme responsible for the metabolism of arachidonic acid to leukotrienes. The elevated levels of this enzyme and its metabolites in cancer cells have a direct relation on the development of cancer when compared to normal cells. The development of novel lipoxygenase inhibitors can have a major role in cancer therapy. A series of substituted 1,4-dihydropyrimidine analogues were synthesized and characterized by 1H-NMR, 13C-NMR, and HRMS. Molecular docking against lipoxygenase enzyme (protein data bank code =3V99) was done using Molecular Operating Environment 2013.08 and Leadit 2.1.2 softwares and showed high affinities. The synthesized compounds were tested for their lipoxygenase inhibitory activity and showed inhibition ranging from 59.37%±0.66% to 81.19%±0.94%. The activity was explained by a molecular docking study. The title compounds were also tested for cytotoxic activity against two human cancer cell lines Michigan Cancer Foundation-7 and human melanoma cells and a normal peripheral blood mononuclear cell line.

Repositioning of 2,4-Dichlorophenoxy acetic acid as a potential anti-inflammatory agent: In Silico and Pharmaceutical Formulation study

2,4-Dichlorophenoxy acetic acid (2,4-D) is a well-known plant auxin which is widely used in plant tissue culture experiments as well as a weed killer and a herbicide. In this study, 2,4-D was rediscovered as a new anti-inflammatory agent through an in silico molecular modeling and docking studies along with drug formulation and in vivo anti-inflammatory inspection. The molecular modeling and docking studies indicated high affinity of 2,4-D toward COX-2 enzyme in a way similar to Ibuprofen, suggesting a higher anti-inflammatory activity. Molecular docking by both MOE 2013.08 and Leadit 2.1.2 revealed excellent binding pattern compared to some of well-known non-steroidal anti-inflammatory drugs. 2,4-D was formulated in different gel bases. In vitro drug release experiments were used to examine the best 2,4-D formula for in vivo studies. In vivo carrageenan-induced hind paw edema inflammatory model in rats was used to test the in silico finding. 2,4-D showed potential in vivo anti-inflammatory activity and significantly reduced the concentration of prostaglandin E2 in hind paw tissues in a way similar to Ibuprofen. These results may open the door to introduce a new anti-inflammatory molecule; especially that 2,4-D is a well-investigated regarding its toxicity and side effect.

Molecular modeling studies and anti-TB activity of trisubstituted indolizine analogues; molecular docking and dynamic inputs

A series of trisubstituted indolizine analogues has been designed as a result of a fragment-based approach to target the inhibition of mycobacterial enoyl-acyl carrier protein reductase. Anti-tuberculosis (TB) screening of the characterized compounds by a resazurin microplate assay method revealed that ethyl group at second position of indolizine nucleus exhibited activity against susceptible and multidrug-resistant strains of Mycobacterium tuberculosis at concentration of 5.5 and 11.3 μg/mL, respectively. A molecular docking study was also conducted to evaluate the stability of the active compounds, and compound with ethyl substitution at second position of indolizine nucleus showed the highest free binding energy of ΔG −24.11 (kcal/mol), a low clash score of 3.04, and high lipo score of −13.33. Indolizine analog with ethyl substitution at second position demonstrated Molecular Mechanics/Generalized Born Surface Area (−23.85 kcal/mol). Two molecular dynamics studies were computed (100 ps and 50 ns) to calculate the relationship between the potential and kinetic energies of the active anti-TB compound with time and temperature. The discovery of this lead may have a positive impact on anti-TB drug discovery.

3-Substituted-4-hydroxycoumarin as a new scaffold with potent CDK inhibition and promising anticancer effect: Synthesis, molecular modeling and QSAR studies.

A new series of 3-substituted-4-hydroxycoumarin derivatives was designed, synthesized, and evaluated for CDK inhibiting and anticancer activities. All the synthesized target compounds showed remarkably high affinity and selectivity towards CDK1B, compared to flavopiridol, with Ki values in the low nanomolar range (Ki=0.35-0.88nM). Most of them elicited considerable inhibiting effect against CDK9T1 (Ki=3.26-23.45nM). Moreover, all the target compounds were tested in vitro against eighteen types of human tumor cell lines. The hydrazone 3a, N-phenylpyrazoline derivative 6b and 2-aminopyridyl-3-carbonitrile derivative 8c were the most potent anticancer agents against MCF-7 breast cancer cell line (IC50=0.21, 0.21 and 0.23nM, respectively). The target compounds 3a, 6b and 8c were further evaluated in MCF-7 breast cancer mouse xenograft model and showed in vivo efficacy at 10mg/kg dose. The docking study confirmed a unique binding mode in the active site of CDK1B with better score than flavopiridol. Quantitative structure activity relationship study was done and revealed a highly predictive power R(2) of 0.81.

Synthesis, Molecular Docking and Preliminary in-Vitro Cytotoxic Evaluation of Some Substituted Tetrahydro- naphthalene (2',3',4',6'-Tetra-O-Acetyl-β-D-Gluco / - Galactopyranosyl) Derivatives

A facile, convenient and high yielding synthesis of novel S-glycosides and N-glycosides incorporating 1,2,3,4-tetrahydronaphthalene and or 1,2-dihydropyridines moieties has been described. The aglycons 2, 4, and 7 were coupled with different activated halosugars in the presence of basic and acidic medium. The preliminary in-vitro cytotoxic evaluation revealed that compounds 3c, 3f, 5c and 7b show promising activity. A molecular docking study was performed against tyrosine kinase (TK) (PDB code: 1t46) by Autodock Vina. The docking output was analyzed and some compounds have shown hydrogen bond (H-B) formation with reasonable distances ranged from 2.06 A° to 3.06 A° with Thr 670 and Cys 673 residues found in the specified pocket. No hydrogen bond was observed with either Glu 640 nor Asp 810 residues, as was expected from pdbsum.

In Silico-Based Repositioning of Phosphinothricin as a Novel Technetium-99m Imaging Probe with Potential Anti-Cancer Activity

l-Phosphinothricin (glufosinate or 2-amino-4-((hydroxy(methyl) phosphinyl) butyric acid ammonium salt (AHPB)), which is a structural analog of glutamate, is a recognized herbicide that acts on weeds through inhibition of glutamine synthetase. Due to the structural similarity between phosphinothricin and some bisphosphonates (BPs), this study focuses on investigating the possibility of repurposing phosphinothricin as a bisphosphonate analogue, particularly in two medicine-related activities: image probing and as an anti-cancer drug. As BP is a competitive inhibitor of human farnesyl pyrophosphate synthase (HFPPS), in silico molecular docking and dynamic simulations studies were established to evaluate the binding and stability of phosphinothricin with HFPPS, while the results showed good binding and stability in the active site of the enzyme in relation to alendronate. For the purpose of inspecting bone-tissue accumulation of phosphinothricin, a technetium (99mTc)–phosphinothricin complex was developed and its stability and tissue distribution were scrutinized. The radioactive complex showed rapid, high and sustained uptake into bone tissues. Finally, the cytotoxic activity of phosphinothricin was tested against breast and lung cancer cells, with the results indicating cytotoxic activity in relation to alendronate. All the above results provide support for the use of phosphinothricin as a potential anti-cancer drug and of its technetium complex as an imaging probe.