Mohamed M. Said

Synthesis and Biological Activity of Functionalized Indole-2-carboxylates, Triazino- and Pyridazino-indoles

Condensation of aryl hydrazines with ethyl pyruvate gave the respective hydrazones 4–6; Fischer indolization led to substituted‐1H‐indole‐2‐carboxylic acid ethyl esters 7–9. The Mannich reaction of these compounds with formaldehyde and morpholine yielded ethyl 3‐(morpholinomethyl)‐substituted‐1H‐indole‐2‐carboxylates 10‐12. The 5,7‐dichloro‐1H‐indole‐2‐carbohydrazide 13 was cyclized with methyl orthoformate in DMF to give 6,8‐dichloro[1,2,4]triazino[4,5‐a]indol‐1(2H)‐one 14. Vilsmeier–Haack formylation of 7–9 gave ethyl 3‐formyl‐substituted‐1H‐indole‐2‐carboxylates 15–17 whose 2,2′‐((5‐chloro‐2‐(ethoxycarbonyl)‐1H‐indol‐3‐yl)methylene)bis‐(sulfanediyl) diacetic acid 18 was prepared. The reaction of 15 and 16 with substituted anilines by conventional and microwave methods gave ethyl 3‐(N‐aryliminomethyl)‐5‐halo‐1H‐indole‐2‐carboxylates 19–29. In a cyclocondensation reaction of 19–25 with thiolactic acid or thioglycolic acid substituted indolylthiazolidinones 30–33 were prepared. Reaction of hydrazine hydrate with 15–17 did not give the respective hydrazones but directly led to the cyclized products substituted‐3H‐pyridazino[4,5‐b]indol‐4(5H)‐ones 34–36, while a reaction with 2,4‐dichlorophenylhydrazine yielded the uncyclized hydrazones. The chlorination of 35 and 36 with POCl3 gave pyridazino[4,5‐b]indoles 39 and 40, respectively; reaction of the latter compounds with morpholine gave 4‐(substituted‐5H‐pyridazino[4,5‐b]indol‐4‐yl)morpholine 41 and 42. Mannich reaction of 34 with formaldehyde and N‐ethylpiperazine gave 8‐chloro‐3‐((4‐ethylpiperazin‐1‐yl)methyl)‐3H‐pyridazino[4,5‐b]indol‐4(5H)‐one 43. The microwave assistance of selected reactions has a profound effect on the reaction speed. The structures of the new compounds were confirmed by both analytical and spectral data. Some compounds were subjected to investigations concerning their antimicrobial, tranquilizing, and anticonvulsant activities.

Synthesis of new spirooxindole-pyrrolothiazole derivatives: Anti-cancer activity and molecular docking

The 1,3-dipolar cycloadditions of an azomethine ylide generated from isatin and thiazolidinecarboxylic acid to a series of 2,6-bis[(E)-arylmethylidene]cyclohexanones afforded new di-spiro heterocycles incorporating pyrrolidine and oxindole rings in quantitative yields and chemo-, regio-, and stereoselectively. The newly synthesized compounds were characterized using spectroscopic techniques. Furthermore, the molecular structures of 4a, 4e, and 4n were confirmed by X-ray crystallography. These newly synthesized compounds were screened for their in vitro activity against breast cancer cell line MCF-7 and K562-leukemia. 4k was found to be the most potent compound of this series in targeting MCF-7 breast cancer cells and K562-leukemia, with IC50 values of 15.32±0.02 and 14.74±0.7μM, respectively. The molecular studies of the synthesized compounds were investigated.

Synthesis, Characterization, and Nanoencapsulation of Tetrathiatriarylmethyl and Tetrachlorotriarylmethyl (Trityl) Radical Derivatives—A Study To Advance Their Applicability as in Vivo EPR Oxygen Sensors

Tissue oxygenation plays an important role in the pathophysiology of various diseases and is often a marker of prognosis and therapeutic response. EPR (ESR) is a suitable noninvasive oximetry technique. However, to reliably deploy soluble EPR probes as oxygen sensors in complex biological systems, there is still a need to investigate and improve their specificity, sensitivity, and stability. We reproducibly synthesized various derivatives of tetrathiatriarylmethyl and tetrachlorotriarylmethyl (trityl) radicals. Hydrophilic radicals were investigated in aqueous solution mimicking physiological conditions by, e.g., variation of viscosity and ionic strength. Their specificity was satisfactory, but the oxygen sensitivity was low. To enhance the capability of trityl radicals as oxygen sensors, encapsulation into oily core nanocapsules was performed. Thus, different lipophilic triesters were prepared and characterized in oily solution employing oils typically used in drug formulations, i.e., middle-chain triglycerides and isopropyl myristate. Our screening identified the deuterated ethyl ester of D-TAM (radical 13) to be suitable. It had an extremely narrow single EPR line under anoxic conditions and excellent oxygen sensitivity. After encapsulation, it retained its oxygen responsiveness and was protected against reduction by ascorbic acid. These biocompatible and highly sensitive nanosensors offer great potential for future EPR oximetry applications in preclinical research.

Design, synthesis, and enzyme kinetics of novel benzimidazole and quinoxaline derivatives as methionine synthase inhibitors.

Methionine synthase catalyzes the transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine, producing methionine and tetrahydrofolate. Benzimidazole and deazatetrahydrofolates derivatives have been shown to inhibit methionine synthase by competing with the substrate 5-methyltetrahydrofolate. In this study, a novel series of substituted benzimidazoles and quinoxalines were designed and assessed for inhibitory activity against purified rat liver methionine synthase using a radiometric enzyme assay. Compounds 3g, 3j, and 5c showed the highest activity against methionine synthase (IC₅₀: 20 μM, 18 μM, 9 μM, respectively). Kinetic analysis of these compounds using Lineweaver-Burk plots revealed characteristics of mixed inhibition for 3g and 5c; and uncompetitive inhibition for 3j. Docking study into a homology model of the rat methionine synthase gave insights into the molecular determinants of the activity of this class of compounds. The identification of these drug-like inhibitors could lead the design of the next generation modulators of methionine synthase.

Synthesis, Biological Evaluation and Molecular Docking of Certain Sulfones as Potential Nonazole Antifungal Agents.

We reported herein the synthesis, antifungal activity, docking and in silico ADME prediction studies of four novel series of sulfones 6a–f, 8a–c, 10a–f and 12a–c. All the newly synthesized sulfones were tested against four strains of Candida (including fluconazole-resistant Candida), two strains of Aspergillus, two dermatophytic fungi (Trichophytons mentagrophyte and Microsporum canis) and Syncephalastrum sp. with fluconazole as a reference drug. In general, compounds 8a and 10b showed selective and potent anticandidal activity (MIC: 0.19–0.81 µM) relative to fluconazole (MIC = 1.00 µM). Furthermore, 10e and 12a elicited a remarkable and selective antifungal activity against Aspergillus sp. and the dermatophytic fungi (MIC: 0.16–0.79 µM) relative to fluconazole (MIC: 2–2.6 µM). Moreover, the docking results of the sulfones 6a, 8a, 10a and 10b at the active site of CYT P450 14α-sterol demethylase showed a comparable binding interaction (interaction Energy = −34.87 to −42.43 kcal/mol) with that of fluconazole (IE = −40.37 kcal/mol).

Regio- and stereoselective synthesis of new spirooxindoles via 1,3-dipolar cycloaddition reaction: Anticancer and molecular docking studies

Owing to their structural novelty and inherent three-dimensionality, spiro scaffolds have been shown indisputable promise as chemopreventive agents. A new series of heterocycles containing spirooxindole and pyrrolidine rings were synthesized by the 1,3-dipolar cycloaddition of an azomethine ylide, which was generated in situ by the condensation of a secondary amino acid (l‑proline) and dicarbonyl compounds (isatin), with dipolarophiles. This method is simple and provides diverse and biologically interesting products. The new series of compounds with a high degree of stereo- and regioselectivity were evaluated against breast cancer cell lines (MCF-7) and leukemia (K562). Among them, compound 4g was identified as the most potent with IC50 values of 15.49 ± 0.04 μM, against breast cancer cell lines (MCF-7) compared to standard drug 5-Fu (IC50 = 78.28 ± 0.2 μM) and compound 4i IC50 values of 13.38 ± 0.14 μM against leukemia (K562) compared to standard drug 5-fluorouracil (5-FU) (IC50 = 38.58 ± 0.02). The selective apoptotic effects of 4g were investigated against MCF-12 normal mammary cell and the cytotoxicity of 4g was not associated with any induction of necrosis compared to untreated cells. Molecular docking studies were investigated. From the docking data, these compounds could be act as small molecules that inhibit the MDM2-p53 interaction.

Discovery of Potent Antiproliferative Agents Targeting EGFR Tyrosine Kinase Based on the Pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4-amine Scaffold

A series of pyridothieno[3,2-d]pyrimidin-4-amines was designed and synthesized as congeners to the classical 4-anilinoquinazolines as ATP-competitive epidermal growth factor receptor (EGFR) inhibitors. Compound 5a exhibited the most potent and selective inhibitory activity against EGFR with an IC50 value of 36.7 nM. Moreover, compounds 4b and 5a showed remarkable cell growth inhibition against leukemia, central nervous system cancer, and non-small cell lung cancer cell lines that overexpress EGFR, with growth inhibition of 50% (GI50) values of around 10 nM in the full U.S. National Cancer Institute 60 cell panel assay. Cell cycle studies indicated that compounds 4b and 5a induced significant cell cycle arrest in the S-phase and G0/G1, respectively, in addition to boosting P27(kip) expression. Compound 5a did not alter the viability of placental trophoblasts, which reflects its safety for normal cells. The standard COMPARE analyses demonstrated considerable correlation levels between compounds 4b and 5a and erlotinib, with pyridinium chlorochromate (PCC) values of 0.707 and 0.727, respectively.

Synthesis and EPR-spectroscopic characterization of the perchlorotriarylmethyl tricarboxylic acid radical (PTMTC) and its

A hydrophilic tris(tetrachlorotriaryl)methyl (tetrachloro-TAM) radical labelled 50% with 13C at the central carbon atom was prepared. The mixture of isotopologue radicals was characterised by continuous wave and pulsed X-band electron paramagnetic spectroscopy (EPS). For the pharmaceutical and medical applications planned, the quantitative influence of oxygen, viscosity, temperature and pH on EPR line widths was studied in aqueous buffer, DMSO, water-methanol and water-glycerol mixtures. Under in vivo conditions, pH can be disregarded. There is a clear oxygen dependence of the width of the 12C isotopologue single EPR line in aqueous solutions while changes in rotational motion (viscosity) are observable only in the doublet lines of the central carbon of the 13C isotopologue. The tetrachloro-TAM proved to be very stable as a solid. Its thermal decay was determined quantitatively by thermal annealing. Towards ascorbic acid as a reducing agent and towards an oocyte cell extract it had a half-life of approx. 60 and 10 min. Thus for in vivo applications, 50% 13C tetrachloro-TAMs are suitable for selective and simultaneous oxygen and macroviscosity measurements in a formulation, e.g. nanocapsules.

Synthesis of Some Novel 2,6-Disubstituted Pyridazin-3(2H)-one Derivatives as Analgesic, Anti-Inflammatory, and Non-Ulcerogenic Agents

Some novel 2,6‐disubstituted pyridazine‐3(2H)‐one derivatives were synthesized and evaluated for in vitro cyclooxygenase‐2 (COX‐2) inhibitory efficacy. Compounds 2‐{[3‐(2‐methylphenoxy)‐6‐oxopyridazin‐1(6H)‐yl]methyl}‐1H‐isoindole‐1,3(2H)‐dione (5a), 2‐propyl‐6‐(o‐tolyloxy)pyridazin‐3(2H)‐one (6a), and 2‐benzyl‐6‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridazin‐3(2H)‐one (16a) showed the most potent COX‐2 inhibitory activity with IC50 values of 0.19, 0.11, and 0.24 μM, respectively. The synthesized compounds with the highest COX‐2 selectivity indices were evaluated for their anti‐inflammatory, analgesic, and ulcerogenic activities. Compounds 6a and 16a demonstrated the most potent and consistent anti‐inflammatory activity over the synthesized compounds, which was significantly higher than that of celecoxib in the carrageenin rat paw edema model and with milder ulcer scoring than that of indomethacin in the ulcerogenicity screening.