Publications by authors named "Saleh Ihmaid"

23 Publications

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Design of molecular hybrids of phthalimide-triazole agents with potent selective MCF-7/HepG2 cytotoxicity: Synthesis, EGFR inhibitory effect, and metabolic stability.

Bioorg Chem 2021 Jun 22;111:104835. Epub 2021 Mar 22.

Pharmacognosy and Pharmaceutical Chemistry Department, College of Pharmacy, Taibah University, Al-Madinah Al-Munawarah, Saudi Arabia; Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Al-Azhar University, 11884 Nasr City, Cairo, Egypt.

This study reports an efficient and convenient click chemistry synthesis of a novel series of phthalimide scaffold linked to 1,2,3 triazole ring and terminal lipophilic fragments. Structures of newly synthesized compounds were well characterized by different spectroscopic tools. In vitro MTT cytotoxicity assay was performed comparing the cytotoxic effects of newly synthesized compounds to staurosporine using three different types: human liver cancer cell line (HepG2), Michigan cancer foundation-7 (MCF-7) and human colorectal carcinoma cell line (HCT116). The initial screening showed excellent to moderate anticancer activity for these newly synthesized compounds with high degree of cell line selectivity with micromolar (µM) half maximal inhibitory concentration (IC) values against tumor cells. The SAR analysis of these derivatives confirmed the role of molecular fragments including phthalimide, linker, triazole, and terminal tails in correlation to activity. In addition, enzymatic inhibitory assay against wild type EGFR was performed for the most active compounds to get more details about their mechanism of action. In order to further explore their binding affinities, molecular docking simulation was studied against EGFR site. The results obtained from molecular docking study and those obtained from cytotoxic screening were correlated. One of the most prominent analogs is (6f) with terminal disubstituted ring and amide linker showed selective MCF-7 cytotoxicity profile with IC 0.22 µM and 79 nM to EGFR target. Extensive structure activity relationship (SAR) analyses were also carried out. The pharmacokinetic profile of (6f) was studied showing good metabolic stability and long duration behavior. This design offered a potent selective anticancer phthalimide-triazole leads for further optimization in cancer drug discovery.
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http://dx.doi.org/10.1016/j.bioorg.2021.104835DOI Listing
June 2021

Design and Synthesis of Novel Imidazole Derivatives Possessing Triazole Pharmacophore with Potent Anticancer Activity, and In Silico ADMET with GSK-3β Molecular Docking Investigations.

Int J Mol Sci 2021 Jan 25;22(3). Epub 2021 Jan 25.

Department of Chemistry, College of Science, Taibah University, Al-Madinah Al-Munawarah 30002, Saudi Arabia.

A library of novel imidazole-1,2,3-triazole hybrids were designed and synthesized based on the hybrid pharmacophore approach. Therefore, copper(I)catalyzed click reaction of thiopropargylated-imidazole 2 with several organoazides yielded two sets of imidazole-1,2,3-triazole hybrids carrying different un/functionalized alkyl/aryl side chains and . After full spectroscopic characterization using different spectral techniques (IR, H, C NMR) and elemental analyses, the resulted adducts were screened for their anticancer activity against four cancer cell lines (Caco-2, HCT-116, HeLa, and MCF-7) by the MTT assay and showed significant activity. In-silico molecular docking study was also investigated on one of the prominent cancer target receptors, i.e., glycogen synthase kinase-3β (GSK-3β), revealing a good binding interaction with our potent compound, and was in agreement with the in vitro cytotoxic results. In addition, the ADMET profile was assessed for these novel derivatives to get an insight on their pharmacokinetic/dynamic attributes. Finally, this research design and synthesis offered click chemistry products with interesting biological motifs mainly 1,2,3 triazoles linked to phenyl imidazole as promising candidates for further investigation as anticancer drugs.
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http://dx.doi.org/10.3390/ijms22031162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7866082PMC
January 2021

Novel scaffold hopping of potent benzothiazole and isatin analogues linked to 1,2,3-triazole fragment that mimic quinazoline epidermal growth factor receptor inhibitors: Synthesis, antitumor and mechanistic analyses.

Bioorg Chem 2020 10 23;103:104133. Epub 2020 Jul 23.

Department of Chemistry, College of Science, Taibah University, Al-Madinah Al-Munawarah 30002, Saudi Arabia.

A series of benzothiazole/isatin linked to 1,2,3-triazole moiety and terminal sulpha drugs 5a-e and 6a-e were synthesized and evaluated for cytotoxic activity against a panel of cancer cell lines. The novel compounds showed variable IC range of activity and some of them were potent compared to reference drug. The promising compounds were subjected as postulated the mimicry proposal for quinazoline-based EGFR inhibitors for their inhibitory profile against EGFR TK enzyme. That data obtained revealed that most of these compounds were potent EGFR TK inhibitors at nanomolar concentrations. Among these, compounds 5a and 5b showed more potent activity on EGFR compared to erlotinib (IC 103 and 104 versus 67.6 nM). Based upon the results, molecular docking analysis was performed on EGFR receptor and proved the strong contribution of fragments; benzothiazole, isatin, and triazole to the binding ATP pocket. When these selected compounds 5a and 5b were tested in an HepG2 model, they could effectively inhibited tumor growth, strongly induced cancer cell apoptosis, and suppressed cell cycle progression leading to DNA fragmentation. Well-DMET profile of the most active derivatives was presented and compared to the reference drugs. Taken together, we introduced novel triazole-sulpha drug hybrid for the first time as EGFR inhibitors and the results of our studies indicate that the newly discovered inhibitors have significant potential for anticancer treatment.
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http://dx.doi.org/10.1016/j.bioorg.2020.104133DOI Listing
October 2020

Novel molecular discovery of promising amidine-based thiazole analogues as potent dual Matrix Metalloproteinase-2 and 9 inhibitors: Anticancer activity data with prominent cell cycle arrest and DNA fragmentation analysis effects.

Bioorg Chem 2020 08 2;101:103992. Epub 2020 Jun 2.

Pharmacognosy and Pharmaceutical Chemistry Department, College of Pharmacy, Taibah University, Al-Madinah Al-Munawarah, Saudi Arabia; Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Al-Azhar University, 11884 Nasr City, Cairo, Egypt.

Thiazole derivatives are known to possess various biological activities such as antiparasitic, antifungal, antimicrobial and antiproliferative activities. Matrix metalloproteinases (MMPs) are important protease target involved in tumor progression including angiogenesis, tissue invasion, and migration. Therefore, MMPs have also been reported as potential diagnostic and prognostic biomarkers in many types of cancer. Herein, new aryl thiazoles were synthesized and evaluated for their anticancer effects on a panel of cancer cell lines including the invasive MDA-MB-231 line. Some of these compounds showed IC values in the submicromolar range in anti-proliferative assays. In order to examine the relationship between their anticancer activity and MMPs targets, the compounds were evaluated for their inhibitory effects on MMP-2 and 9. That data obtained revealed that most of these compounds were potent dual MMP-2/9 inhibitors at nanomolar concentrations. Among these, 2-(1-(2-(2-((E)-4-iodobenzylidene)hydrazineyl)-4-methylthiazol-5-yl)ethylidene)hydrazine-1-carboximidamide (4a) was the most potent non-selective dual MMP-2/9 inhibitor with inhibitory concentrations of 56 and 38 nM respectively. When compound 4a was tested in an MDA-MB-231, HCT-116, MCF-7 model, it effectively inhibited tumor growth, strongly induced cancer cell apoptosis, inhibit cell migration, and suppressed cell cycle progression leading to DNA fragmentation. Taken together, the results of our studies indicate that the newly discovered thiazole-based MMP-2/9 inhibitors have significant potential for anticancer treatment.
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http://dx.doi.org/10.1016/j.bioorg.2020.103992DOI Listing
August 2020

The rational design, synthesis, and antimicrobial investigation of 2-Amino-4-Methylthiazole analogues inhibitors of GlcN-6-P synthase.

Bioorg Chem 2020 06 21;99:103781. Epub 2020 Mar 21.

Pharmacognosy and Pharmaceutical Chemistry Department, Pharmacy College, Taibah University, Al-Madinah Al-Munawarah 41477, Saudi Arabia; Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Al-Azhar University, Nasr City 11884, Cairo, Egypt. Electronic address:

A series of novel 2-Amino-4-Methylthiazole analogs were developed via three-step reaction encompassing hydrazine-1-carboximidamide motif to combat Gram-positive and Gram-negative bacterial and fungal infections. Noticeably, the thiazole-carboximidamide derivatives 4a-d displayed excellent antimicrobial activity and the most efficacious analogue 4d with MIC/MBC values of 0.5 and 4 μg/mL, compared to reference drugs with very low toxicity to mammalian cells, resulting in a prominent selectivity more than 100 folds. Microscopic investigation of 4d biphenyl analogue showed cell wall lysis and promote rapid bactericidal activity though disrupting the bacterial membrane. In addition, an interesting in vitro investigation against GlcN-6-P Synthase Inhibition was done which showed potency in the nanomolar range. Meanwhile, this is the first study deploying a biomimicking strategy to design potent thiazole-carboximidamides that targeting GlcN-6-P Synthase as antimicrobial agents. Importantly, Molecular modeling simulation was done for the most active 4d analogue to study the interaction of this analogue which showed good binding propensity to glucosamine binding site which support the in vitro data.
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http://dx.doi.org/10.1016/j.bioorg.2020.103781DOI Listing
June 2020

Introducing of acyclonucleoside analogues tethered 1,2,4-triazole as anticancer agents with dual epidermal growth factor receptor kinase and microtubule inhibitors.

Bioorg Chem 2020 01 23;94:103446. Epub 2019 Nov 23.

Department of Chemistry, Faculty of Sciences, Taibah University, Al-Madinah Al-Munawarah 30002, Saudi Arabia; Laboratoire de Chimie & Electrochimie des Complexes Métalliques (LCECM) USTO-MB, Department of Chemistry, Faculty of Sciences, University of Sciences and Technology Mohamed Boudiaf, B.p. 1505 El M nouar, Oran 31000, Algeria.

This study reports an efficient and convenient regioselective synthesis of a novel series of S- and S,N-bis(acyclonucleoside) analogues carrying 5-(2-chlorophenyl)-2,4-dihydro-1,2,4-triazole-3-thione. A facile and straightforward synthesis of thiazolotriazole and triazolothiazines has also been reported. Structures of all newly synthesized compounds were well characterized by infrared IR, H and C nuclear magnetic resonance (NMR) and mass (MS) spectra analyses. Cytotoxic screening was performed according to (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium (MTT) assay method using staurosporine as a reference drug against three different types: human liver cancer cell line (Hep G2), Michigan cancer foundation-7 (MCF-7) and human colorectal carcinoma cell line (HCT116). These data showed considerable anticancer activity for these newly synthesized compounds. Biological data for most of the S-acyclonucleoside analogues and S,N-bis(acyclonucleoside) analogues showed excellent activity with micromolar (µM) half maximal inhibitory concentration (IC) values against tumor cells. EGFR assay and tubulin inhibition assay analysis were performed for the most active compounds to get more details about their mechanism of action. In order to assess and explain their binding affinities, molecular docking simulation was studied against EGFR and tubulin binding sites. The results obtained from molecular docking study and those obtained from cytotoxic screening were correlated. Extensive structure activity relationship (SAR) analyses were also carried out.
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http://dx.doi.org/10.1016/j.bioorg.2019.103446DOI Listing
January 2020

First example of Azo-Sulfa conjugated chromene moieties: Synthesis, characterization, antimicrobial assessment, docking simulation as potent class I histone deacetylase inhibitors and antitumor agents.

Bioorg Chem 2019 11 5;92:103262. Epub 2019 Sep 5.

Chemistry Department, Faculty of Science, Taibah University, 30002, Al-Madinah Al-Munawarah, Saudi Arabia; Chemistry Department, Faculty of Science, Al-Azhar University, 11884 Nasr City, Cairo, Egypt. Electronic address:

This report presents the development of a novel and primary model of sulfonamide compounds encompassing a chromene azo motif with the intent of becoming applicable for drug candidates in the cases of drug-resistant pathogens. The novel molecules (7a-n) have been synthesized via a two-step reaction. First, 4-((2, 4-dihydroxyphenyl)diazenyl)benzenesulfonamide (3a-e) were obtained through the reaction of their corresponding diazotized 4-aminobenzenesulfonamides (1a-e) with resorcinol, followed by the heterocyclization of 3a-e with arylidenemalononitriles (6a-d). Upon structural identification, the newly synthesized compounds were evaluated for their antibacterial and antifungal activities. Moreover, their cytotoxic screening was performed against three cancer cell lines: HCT-116, HepG-2, and MCF-7. Further examinations were comprised of the inhibitory effect analyses of the novel sulfonamide/chromene derivatives against the HDAC classes and the Tubulin polymerization in order to discern the prime antitumor drug candidates.
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http://dx.doi.org/10.1016/j.bioorg.2019.103262DOI Listing
November 2019

Introducing novel potent anticancer agents of 1H-benzo[f]chromene scaffolds, targeting c-Src kinase enzyme with MDA-MB-231 cell line anti-invasion effect.

J Enzyme Inhib Med Chem 2018 Dec;33(1):1074-1088

c Chemistry Department, Faculty of Science , Al-Azhar University , Cairo , Egypt.

In our effort to develop novel and powerful agents with anti-proliferative activity, two new series of 1H-benzo[f]chromene derivatives, 4a-h and 6a-h, were synthesised using heterocyclocondensation methodologies under microwave irradiation condition. The structures of the target compounds were established on the basis of their spectral data, IR, H NMR,  C NMR,  C NMR-DEPT/APT, and MS data. The new compounds have been examined for their anti-proliferative activity against three cancer cell lines, MCF-7, HCT-116, and HepG-2. Vinblastine and Doxorubicin have been used as positive controls in the viability assay. The obtained results confirmed that most of the tested molecules revealed strong and selective cytotoxic activity against the three cancer cell lines. Moreover, these molecules exhibited weak cytotoxicity on the HFL-1 line, which suggested that they might be ideal anticancer candidates. The SAR study of the new benzochromene compounds verified that the substituents on the phenyl ring of 1H-benzo[f]chromene nucleus, accompanied with the presence of bromine atom or methoxy group at the 8-position, increases the ability of these molecules against the different cell lines. Due to their high anti-proliferative activity, compounds 4c and 6e were selected to be examined their proficiency to inhibit the invasiveness of the highly sensitive and invasive breast cancer cell line, MDA-MB-231. The anti-invasion behaviour of these molecules against the highly sensitive, non-oestrogen, and progesterone MDA-MB-231 cell line gave rise to their decreasing metastatic effect compared to the reference drug. Furthermore, this report explores the apoptotic mechanistic pathway of the cytotoxicity of the target compounds and reveals that most of these compounds enhance the Caspase 3/7 activity that could be considered as potential anticancer agents.
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http://dx.doi.org/10.1080/14756366.2018.1476503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6022228PMC
December 2018

Design, Synthesis, Cytotoxic Evaluation and Molecular Docking of New Fluoroquinazolinones as Potent Anticancer Agents with Dual EGFR Kinase and Tubulin Polymerization Inhibitory Effects.

Int J Mol Sci 2018 06 11;19(6). Epub 2018 Jun 11.

Pharmacognosy and Pharmaceutical Chemistry Department, College of Pharmacy, Taibah University, Al-Madinah Al-Munawarah 41477, Saudi Arabia.

A series of new fluoroquinazolinone ⁻ and ⁻ derivatives was designed, prepared and screened for their in vitro cytotoxic activity against human cancer cell lines MCF-7 and MDA-MBA-231. Compounds (IC = 0.35 ± 0.01 µM), (IC = 0.71 ± 0.01 µM), (IC = 0.89 ± 0.02 µM) and (IC = 0.95 ± 0.01 µM) displayed broad spectrum anticancer activity better than the reference drug gefitinib (IC = 0.97 ± 0.02 µM) against MCF-7. Compounds (IC = 0.28 ± 0.02 µM), (IC = 0.38 ± 0.01 µM), (IC = 0.94 ± 0.07 µM) and (IC = 1.09 ± 0.01 µM) showed better activity than the reference gefitinib (IC = 1.30 ± 0.04 µM) against MDA-MBA-231. Moreover, EGFR and tubulin inhibition assays were performed for the highest active derivatives and showed remarkable results comparing to the reference drugs. In order to assess and explain their binding affinities, molecular docking simulation was studied against EGFR and tubulin binding sites. The results obtained from molecular docking study and those obtained from cytotoxic screening were correlated.
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http://dx.doi.org/10.3390/ijms19061731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6032053PMC
June 2018

Exploring the Dual Inhibitory Activity of Novel Anthranilic Acid Derivatives towards α-Glucosidase and Glycogen Phosphorylase Antidiabetic Targets: Design, In Vitro Enzyme Assay, and Docking Studies.

Authors:
Saleh Ihmaid

Molecules 2018 May 29;23(6). Epub 2018 May 29.

Pharmacognosy and Pharmaceutical Chemistry Department, Pharmacy College, Taibah University, Al-Madinah Al-Munawarah 41477, Saudi Arabia.

A few new anthranilate diamide derivatives, ⁻, ⁻ and ⁻, were designed, synthesized, and evaluated for their inhibitory activity against two interesting antidiabetic targets, α-glucosidase and glycogen phosphorylase enzymes. Different instrumental analytical tools were applied in identification and conformation of their structures like; C NMR, ¹H NMR and elemental analysis. The screening of the novel compounds showed potent inhibitory activity with nanomolar concentration values. The most active compounds () and () showed the highest inhibitory activity against α-glucosidase and glycogen phosphorylase enzymes IC = 0.01247 ± 0.01 µM and IC = 0.01372 ± 0.03 µM, respectively. In addition, in vivo testing of the highly potent α-glucosidase inhibitor () on rats with DTZ-induced diabetes was done and showed significant reduction of blood glucose levels compared to the reference drug. Furthermore, a molecular docking study was performed to help understand the binding interactions of the most active analogs with these two enzymes. The data obtained from the molecular modeling were correlated with those obtained from the biological screening. These data showed considerable antidiabetic activity for these newly synthesized compounds.
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http://dx.doi.org/10.3390/molecules23061304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6100603PMC
May 2018

The Design and Development of Potent Small Molecules as Anticancer Agents Targeting EGFR TK and Tubulin Polymerization.

Int J Mol Sci 2018 Jan 30;19(2). Epub 2018 Jan 30.

Pharmacognosy and Pharmaceutical Chemistry Department, Pharmacy College, Taibah University, Al-Madinah Al-Munawarah 41477, Saudi Arabia.

Some novel anthranilate diamides derivatives -, - and - were designed and synthesized to be evaluated for their in vitro anticancer activity. Structures of all newly synthesized compounds were confirmed by infra-red (IR), high-resolution mass (HR-MS) spectra, ¹H nuclear magnetic resonance (NMR) and C nuclear magnetic resonance (NMR) analyses. Cytotoxic screening was performed according to (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium (MTT) assay method using erlotinib as a reference drug against two different types of breast cancer cells. The molecular docking study was performed for representative compounds against two targets, epidermal growth factor receptor (EGFR) and tubulin in colchicine binding site to assess their binding affinities in order to rationalize their anticancer activity in a qualitative way. The data obtained from the molecular modeling was correlated with that obtained from the biological screening. These data showed considerable anticancer activity for these newly synthesized compounds. Biological data for most of the anthranilate diamide showed excellent activity with nanomolar or sub nanomolar half maximal inhibitory concentration (IC) values against tumor cells. EGFR tyrosine kinase (TK) inhibition assay, tubulin inhibition assay and apoptosis analysis were performed for selected compounds to get more details about their mechanism of action. Extensive structure activity relationship (SAR) analyses were also carried out.
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http://dx.doi.org/10.3390/ijms19020408DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5855630PMC
January 2018

Design, Synthesis and Cytotoxic Evaluation of Novel Chalcone Derivatives Bearing Triazolo[4,3-a]-quinoxaline Moieties as Potent Anticancer Agents with Dual EGFR Kinase and Tubulin Polymerization Inhibitory Effects.

Molecules 2017 Dec 27;23(1). Epub 2017 Dec 27.

Pharmacognosy and Pharmaceutical Chemistry Department, Pharmacy College, Taibah University, Al-Madinah Al-Munawarah 41477, Saudi Arabia.

A series of hybrid of triazoloquinoxaline-chalcone derivatives - were designed, synthesized, fully characterized, and evaluated for their cytotoxic activity against three target cell lines: human breast adenocarcinoma (MCF-7), human colon carcinoma (HCT-116), and human hepatocellular carcinoma (HEPG-2). The preliminary results showed that some of these chalcones like -, and - exhibited significant antiproliferative effects against most of the cell lines, with selective or non-selective behavior, indicated by IC values in the 1.65 to 34.28 µM range. In order to investigate the mechanistic aspects of these active compounds, EGFR TK and tubulin inhibitory activities were measured as further biological assays. The EGFR TK assay results revealed that the derivatives -, , and could inhibit the EGFR TK in the submicromolar range (0.093 to 0.661 µM). Moreover, an antitubulin polymerization effect was noted for the active derivatives compared to the reference drug colchicine, with compounds and displaying 14.7 and 8.4 micromolar activity, respectively. Furthermore, a molecular docking study was carried out to explain the observed effects and the binding modes of these chalcones with the EGFR TK and tubulin targets.
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http://dx.doi.org/10.3390/molecules23010048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5943945PMC
December 2017

Design, synthesis, molecular docking of new lipophilic acetamide derivatives affording potential anticancer and antimicrobial agents.

Bioorg Chem 2018 02 2;76:332-342. Epub 2017 Dec 2.

The Regional Center for Mycology and Biotechnology, Al-Azhar University, Cairo, Egypt.

Fifteen new substituted N-2-(2-oxo-3-phenylquinoxalin-1(2H)-yl) acetamides 5a-f, 6a-f, and 8a-c were synthesized by reacting ethyl 2-(2-oxo-3-phenylquinoxalin-1(2H)-yl)acetate with various primary amines including benzylamines, sulfonamides, and amino acids. The in vitro antimicrobial screening of the target compounds was screened to assess their antibacterial and antifungal activity. As a result, seven compounds namely; 5a, 5c, 5d, 6a, 6c, 8b and 8c showed a promising broad spectrum antibacterial activity against both Gram-positive and Gram-negative strains. Among these, the analogs 5c and 6d were nearly as equiactive as ciprofloxacin drug. Meanwhile, four compounds namely; 5c, 6a, 6f and 8c exhibited appreciable antifungal activity with MIC values range 33-40 mg/mL comparable with clotrimazole (MIC 25 mg/mL). In addition, the anticancer effects of the synthesized compounds were evaluated against three cancer lines. The data obtained revealed the benzylamines and sulpha derivatives were the most active compounds especially 5f and 6f ones. Further EGFR enzymatic investigation was carried out for these most active compounds 5f and 6f resulting in inhibitory activity by 1.89 and 2.05 µM respectively. Docking simulation was performed as a trial to study the mechanisms and binding modes of these compounds toward the enzyme target, EGFR protein kinase enzyme. The results revealed good compounds placement in the active sites and stable interactions similar to the co-crystallized reference ligand. Collectively, the analogs 5f and 6f could be further utilized and optimized as good cytotoxic agents.
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http://dx.doi.org/10.1016/j.bioorg.2017.11.019DOI Listing
February 2018

Rational design, synthesis, pharmacophore modeling, and docking studies for identification of novel potent DNA-PK inhibitors.

Bioorg Chem 2017 06 2;72:234-247. Epub 2017 May 2.

Pharmacognosy and Pharmaceutical Chemistry Department, College of Pharmacy, Taibah University, Al-Madinah Al-Munawarah, Saudi Arabia; Department of Pharmaceutical and Medicinal Chemistry, Pharmacy College, Misr University for Science and Technology, Cairo, Egypt.

Drugs of cancer based upon ionizing radiation or chemotherapeutic treatment may affect breaking of DNA double strand in cell. DNA-PK enzyme has emerged as an attractive target for drug discovery efforts toward DNA repair pathways. Hence, the search for potent and selective DNA-PK inhibitors has particularly considered state-of-the art and several series of inhibitors have been designed. In this article, a novel benchmark DNA-PK database of 43 compounds was built and described. Ligand-based approaches including pharmacophore and QSAR modeling were applied and novel models were introduced and analyzed for predicting activity test for DNA-PK drug candidates. Based upon the modeling results, we gave a report of synthesis of fifteen novel 2-((8-methyl-2-morpholino-4-oxo-4H-benzo[e][1,3]oxazin-7-yl)oxy)acetamide derivatives and in vitro evaluation for DNA-PK inhibitory and antiproliferative activities. These fifteen compounds overall are satisfied with Lipinski's rule of five. The biological testing of target compounds showed five promising active compounds 7c, 7d, 7f, 9e and 9f with micromolar DNA-PK activity range from 0.25 to 5µM. In addition, SAR of the compounds activity was investigated and confirmed that the terminal aryl moiety was found to be quite crucial for DNA-PK activity. Moreover flexible docking simulation was done for the potent compounds into the putative binding site of the 3D homology model of DNA-PK enzyme and the probable interaction model between DNA-PK and the ligands was investigated and interpreted.
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http://dx.doi.org/10.1016/j.bioorg.2017.04.014DOI Listing
June 2017

Synthesis, Modelling, and Anticonvulsant Studies of New Quinazolines Showing Three Highly Active Compounds with Low Toxicity and High Affinity to the GABA-A Receptor.

Molecules 2017 Jan 24;22(2). Epub 2017 Jan 24.

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo 11884, Egypt.

Some novel fluorinated quinazolines (-) were designed and synthesized to be evaluated for their anticonvulsant activity and their neurotoxicity. Structures of all newly synthesized compounds were confirmed by their infrared (IR), mass spectrometry (MS) spectra, ¹H nuclear magnetic resonance (NMR), C-NMR, and elemental analysis (CHN). The anticonvulsant activity was evaluated by a subcutaneous pentylenetetrazole (scPTZ) test and maximal electroshock (MES)-induced seizure test, while neurotoxicity was evaluated by a rotorod test. The molecular docking was performed for all newly-synthesized compounds to assess their binding affinities to the GABA-A receptor in order to rationalize their anticonvulsant activities in a qualitative way. The data obtained from the molecular modeling was correlated with that obtained from the biological screening. These data showed considerable anticonvulsant activity for all newly-synthesized compounds. Compounds , , and showed the highest binding affinities toward the GABA-A receptor, along with the highest anticonvulsant activities in experimental mice. These compounds also showed low neurotoxicity and low toxicity in the median lethal dose test compared to the reference drugs. A GABA enzymatic assay was performed for these highly active compounds to confirm the obtained results and explain the possible mechanism for anticonvulsant action. The most active compounds might be used as leads for future modification and optimization.
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http://dx.doi.org/10.3390/molecules22020188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6155771PMC
January 2017

Self Organizing Map-Based Classification of Cathepsin k and S Inhibitors with Different Selectivity Profiles Using Different Structural Molecular Fingerprints: Design and Application for Discovery of Novel Hits.

Molecules 2016 Jan 30;21(2):175. Epub 2016 Jan 30.

Pharmacognosy and Pharmaceutical Chemistry Department, College of Pharmacy, Taibah University, P. O. Box 30039, Al-Madinah Al-Munawarah 41477, Saudi Arabia.

The main step in a successful drug discovery pipeline is the identification of small potent compounds that selectively bind to the target of interest with high affinity. However, there is still a shortage of efficient and accurate computational methods with powerful capability to study and hence predict compound selectivity properties. In this work, we propose an affordable machine learning method to perform compound selectivity classification and prediction. For this purpose, we have collected compounds with reported activity and built a selectivity database formed of 153 cathepsin K and S inhibitors that are considered of medicinal interest. This database has three compound sets, two K/S and S/K selective ones and one non-selective KS one. We have subjected this database to the selectivity classification tool 'Emergent Self-Organizing Maps' for exploring its capability to differentiate selective cathepsin inhibitors for one target over the other. The method exhibited good clustering performance for selective ligands with high accuracy (up to 100 %). Among the possibilites, BAPs and MACCS molecular structural fingerprints were used for such a classification. The results exhibited the ability of the method for structure-selectivity relationship interpretation and selectivity markers were identified for the design of further novel inhibitors with high activity and target selectivity.
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http://dx.doi.org/10.3390/molecules21020175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6272978PMC
January 2016

Discovery of novel phthalimide analogs: Synthesis, antimicrobial and antitubercular screening with molecular docking studies.

EXCLI J 2016 6;15:781-796. Epub 2016 Dec 6.

Chemistry Department, Faculty of Science, Taibah University, 30002, Al-Madinah Al-Munawarah, Saudi Arabia.

In continuation of our endeavor towards the design and development of potent and effective antimicrobial agents, three series of phthalimide derivatives ( and ) were synthesized, fully characterized and evaluated for their potential antibacterial, antifungal and antimycobacterial activities. These efforts led to the discovery of nine compounds , and (MIC range from 0.49 to 31.5 μg/mL) with potent antibacterial, antifungal, and antimycobacterial activities. Ampicillin, ciprofloxacin, amphotericin B were used as references for antibacterial and antifungal screening respectively, while isoniazid was used as a reference for antimycobacterial testing. Furthermore, molecular modeling studies were done to explore the binding mode of the most active derivatives to M. tuberculosis enoyl reductase (InhA) and DNA gyrase B. Our study showed the importance of both hydrogen bonding and hydrophobic interactions as a key interaction with the target enzymes.
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http://dx.doi.org/10.17179/excli2016-654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5318679PMC
December 2016

Radiosensitizing activity of a novel Benzoxazine through the promotion of apoptosis and inhibition of DNA repair.

Invest New Drugs 2014 Jun 14;32(3):424-35. Epub 2014 Mar 14.

School of Pharmacy and Applied Science, La Trobe Institute of Molecular Sciences, La Trobe University, P.O. Box 199, Bendigo, VIC, 3552, Australia.

The DNA dependant protein kinase (DNA-PK) enzyme plays a major part in the repair of double stranded breaks induced by radiation and hence in the radio-resistance of tumour cells. Inhibitors of DNA-PK have been tested successfully in the past for their ability to sensitize cancer cells to the effects of radiation. Here we present a novel benzoxazine, 8-methyl-2-(morpholine-4yl)-7-(pyridine-3-methoxy)-4H-1,3-benzoxacine-4-one (LTU27) and analyse its ability to cause sensitization of lung cancer and colon cancer cells to radiation. There was a significant reduction in survival rate, increase in apoptosis and inhibition in autophosphorylation of DNA-PK and AKT1 after treating them concomitantly with both radiation and LTU27. The mechanism of action appears to be through inhibition of DNA-PK leading to delayed DNA repair and promotion of apoptosis.
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http://dx.doi.org/10.1007/s10637-014-0079-4DOI Listing
June 2014

Chemo-sensitisation of HeLa cells to etoposide by a benzoxazine in the absence of DNA-PK inhibition.

Invest New Drugs 2013 Dec 22;31(6):1466-75. Epub 2013 Sep 22.

La Trobe Institute of Molecular Science, La Trobe University, Bendigo, Australia.

The benzoaxines have been developed from structurally similar chromones as specific inhibitors of the PI3K family to sensitize cancer cells to the effects of chemotherapeutic agents; most have been shown to do this through specific inhibition of DNA-PK and DNA repair mechanisms. In this study we examined the benzoxazine, 2-((3-methoxybut-3en-2-yl)amino)-8methyl-4H-benzo[1,3]oxazin-4one (LTUSI54). This compound had no DNA-PK or PI3K inhibitory activity but still sensitized HeLa cells to the effects of Etoposide. LTUSI54 works synergistically with Etoposide to inhibit growth of HeLa cells and sub G1 analysis indicates that this is not due to an increase in apoptosis. LTUSI54 neither enhances DSB formation due to Etoposide nor does it delay the repair of such damage. Cell cycle analysis shows a clear G2 block with Etoposide alone while, in combination with LTUSI54 there is an additional S phase arrest. Phospho-kinase analysis indicated that LTUSI54 engages key regulators of cell cycle progression, specifically p38α, p53 and ERK 1/2. From our results we hypothesize that LTUSI54 is promoting the cell cycle arrest through activation of p38α pathways, independent of p53 mechanisms. This results in a decrease in p53 phosphorylation and hence, restricted apoptosis. Changes in cell number appear to be the result of p38α pathways disrupting cell cycle progression, at the S and G2 checkpoints. Further investigation into the finer mechanisms by which LTUSI54 effects cell cycle progression would be of great interest in assessing this compound as a chemosensitising agent.
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http://dx.doi.org/10.1007/s10637-013-0031-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3825418PMC
December 2013

Synthesis Characterization and Antibacterial, Antifungal Activity of N-(Benzyl Carbamoyl or Carbamothioyl)-2-hydroxy Substituted Benzamide and 2-Benzyl Amino-Substituted Benzoxazines.

Int J Med Chem 2013 31;2013:436397. Epub 2013 Oct 31.

School of Pharmacy and Applied Science, La Trobe University, P.O. Box 199, Bendigo, UIC 3552, Australia.

New N-(benzyl carbamothioyl)-2-hydroxy substituted benzamides 13, 20, and 21 were synthesized using sodium bicarbonate and benzyl amine with 2-thioxo-substituted-1,3-benzoxazines 6, 10a, b, 11c, and 12a-n. The 2-thioxo-substituted-1,3-oxazines 6, 10a-b, 11d 12a-n, and 26 were converted to the corresponding 2-methylthio-substituted-1,3-oxazines 14a-l and 24 which were then converted to 2-benzyl amino-substituted-benzoxazines 15a-i by refluxing with benzylamine. Products 15a, b, e, f, and g were also synthesized by boiling the corresponding N-(benzyl carbamothioyl)-2-hydroxy substituted benzamides 13a, b, f, l, and m in acetic acid. 2-Oxo-substituted-1,3-benzoxazines 22 and 25 were prepared by treating the corresponding 2-methylthio-substituted-1,3-oxazines 14 and 24 with dilute HCl. The N-(benzyl carbamoyl)-2-hydroxy substituted benzamide 23 was synthesized from the reaction of 2-oxo-substituted-1,3-benzoxazine 22 with benzylamine. The new products were characterized using IR, (1)H, and (13)C NMR in addition to microanalysis. Selected compounds were tested in vitro for antibacterial and antifungi activity and the most active compounds were found to be the 4-(substituted-benzylamino)-2-hydroxy benzoic acids 9a and d (M. chlorophenolicum, MIC 50 and 25 µgm L(-1), resp.), N1, N3-bis (benzyl carbamothioyl)-4,6-dihydroxy-substituted phthalamides 20a and 20c (B. subtilis MIC 12.5, 50 µgm L(-1), resp.) and 21 (M. chlorophenolicum, MIC 50 µgm L(-1)).
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http://dx.doi.org/10.1155/2013/436397DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4207449PMC
November 2014

Synthesis, DNA-PK inhibition, anti-platelet activity studies of 2-(N-substituted-3-aminopyridine)-substituted-1,3-benzoxazines and DNA-PK and PI3K inhibition, homology modelling studies of 2-morpholino-(7,8-di and 8-substituted)-1,3-benzoxazines.

Eur J Med Chem 2012 Nov 5;57:85-101. Epub 2012 Sep 5.

School of Pharmacy and Applied Science, La Trobe University, P.O. Box 199, Bendigo, VIC 3552, Australia.

A number of new 2-(pyridin-3-ylamino)-4H-(substituted) benz[e]-1,3-oxazin-4-ones were synthesized 10a-g. These were then reacted with the hydro-halogen salt of 2, 3 and 4-(halo-methyl) pyridine in the presence of Cs(2)CO(3) to give eighteen new 2-(N-substituted (pyridin-3-ylmethyl) amino)-substituted-1,3-benzoxazines (compounds 11a-i, 13a-c, and 15a-f). X-ray crystallography was used to confirm that the 2-N-substituted structures 11 and 13 were formed rather than the 3-N-substitution analogues 12 and 14. Eleven of the new compounds were tested for their effect on collagen induced platelet aggregation and it was found that the most active inhibitory compound was 8-methyl-2-(pyridin-3-yl(pyridin-3-ylmethyl)amino)-7-(pyridin-3-ylmethoxy)-4H-benz[e]-1,3-oxazin-4-one 15e with an IC(50) of 10 ± 2 μM. DNA-dependent protein kinase (DNA-PK) inhibition data for 12 previously prepared 2-morpholino substituted-1,3-benzoxazines (compounds 19-31) were measured and showed high to moderate activity where the most active compound was compound 27 with an IC(50) of 0.28 μM. Furthermore DNA-PK inhibition data for six newly prepared 2-(N-substituted (pyridin-3-ylmethyl) amino)-substituted-1,3-benzoxazines (compounds 11b, 13a-b, 15a-b and 15e) and 8-methyl-7-(pyridin-3-ylmethoxy)-3-(pyridin-3-ylmethyl)-2H-benz[e]-1,3-oxazin-2,4(3H)-dione 17d were measured and moderate to low inhibitory activity was observed, with the most active of the compounds in this series being 8-methyl-2-(pyridin-3-yl(pyridin-3-ylmethyl)amino)-7-(pyridin-3-ylmethoxy)-4H-benz[e]-1,3-oxazin-4-one 15e with an IC(50) of 2.5 μM. PI3K inhibition studies revealed that compound 27 is highly potent (IC(50) for PI3Kα = 0.13 μM, PI3Kβ = 0.14 μM, PI3Kγ = 0.72 μM, PI3Kδ = 2.02 μM). Compound 22 with 7-[2-(4-methylpiperazin-1-yl)ethoxy] group shows greater inhibition of DNA-PK over PI3K. Docking of some 2-morpholino-substituted-1,3-benzoxazine compounds 19-31 within the binding pocket and structure-activity relationships (SAR) analyses were performed with results agreeing well with observed activities.
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http://dx.doi.org/10.1016/j.ejmech.2012.08.035DOI Listing
November 2012

Synthesis, structural elucidation, DNA-PK inhibition, homology modelling and anti-platelet activity of morpholino-substituted-1,3-naphth-oxazines.

Bioorg Med Chem 2011 Jul 24;19(13):3983-94. Epub 2011 May 24.

School of Pharmacy and Applied Science, La Trobe University, Bendigo, Australia.

A number of new angular 2-morpholino-(substituted)-naphth-1,3-oxazines (compound 10b), linear 2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 13b-c), linear 6, 7 and 9-O-substituted-2-morpholino-(substituted)-naphth-1,3-oxazines (compounds 17-22, 24, and 25) and angular compounds 14-16 and 23 were synthesised. The O-substituent was pyridin-2yl-methyl (15, 18, and 21) pyridin-3yl-methyl (16, 19, and 22) and 4-methylpipreazin-1-yl-ethoxy (23-25). Twelve compounds were tested for their inhibitory effect on collagen induced platelet aggregation and it was found that the most active compounds were compounds 19 and 22 with IC(50)=55±4 and 85±4 μM, respectively. Furthermore, the compounds were also assayed for their ability to inhibit DNA-dependent protein kinase (DNA-PK) activity. The most active compounds were 18 IC(50)=0.091 μM, 24 IC(50)=0.191 μM, and 22 IC(50)=0.331 μM. Homology modelling was used to build a 3D model of DNA-PK based on the X-ray structure of phosphatidylinositol 3-kinases (PI3Ks). Docking of synthesised compounds within the binding pocket and structure-activity relationships (SAR) analyses of the poses were performed and results agreed well with observed activity.
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http://dx.doi.org/10.1016/j.bmc.2011.05.032DOI Listing
July 2011

Synthesis, structural elucidation and DNA-dependant protein kinase and antiplatelet studies of 2-amino-[5, 6, 7, 8-mono and 7, 8-di-substituted]-1,3-benzoxazines.

Eur J Med Chem 2010 Nov 12;45(11):4934-46. Epub 2010 Aug 12.

School of Pharmacy and Applied Science, La Trobe University, P.O. Box 199, Bendigo 3552, Australia.

A number of new 2-amino-[5, 6, 7 and 8]-O-substituted 1,3-benzoxazines, and 2-amino 8-methyl-7-O-substituted-1,3-benzoxazines were synthesized. Thirty one new compounds were tested for their effect on collagen induced platelet aggregation and it was found that the most active compounds were 8-methyl-2-morpholin-4-yl-7-(pyridin-3-ylmethoxy)-4H-1,3-benzoxazin-4-one 9f and 8-methyl-2-morpholin-4-yl-7-(pyridin-4-ylmethoxy)-4H-1,3-benzoxazin-4-one 9j with IC(50) = 2 ± 1.5 and 4 ± 2 μM respectively. Inhibition of DNA-PK activity at concentrations of 1.6-4 μM were tested for 9 products 5i, 7a-e and 9b, 9f and 9j.
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http://dx.doi.org/10.1016/j.ejmech.2010.07.066DOI Listing
November 2010
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