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    Novel piperazine and morpholine substituted quinolines: Selective synthesis through activation of 3,6,8-tribromoquinoline, characterization and their some metabolic enzymes inhibition potentials
    (ELSEVIER, 2020) Cakmak, Osman; Okten, Salih; Alimli, Dilek; Ersanli, Cem Cuneyt; Taslimi, Parham; Kocyigit, Umit Muhammet
    Regioselective routes are described for convenient preparation of novel piperazine/morpholine substituted quinoline derivatives at C-3, C-6 and C-8 starting with 3,6,8-tribromoquinoline (6) by nucleophilic substitution via conventional heating or microwave assisted reaction conditions. 3,6,8-Tribromoquinoline (6) was treated with piperazine and morpholine under microvawe irradiation, which selectively furnished 3-mopholinyl and 3-piperazinyl quinoline derivatives 7 and 8 in yields of 58% and 60%, respectively. On the other hand, the activation of benzene cycle of quinoline by nitration of 3,6,8-tribromoquinoline, giving 5-nitro-3,6,8-tribromoquinoline (18) in quantitative yield, was enabled. Then, the bromines at C-6 and C-8 were selectively exchanged by morpholine and piperazine via SNAr reactions. Thus, 6,8-dimopholinylquinoline (22) and 5-nitro-6,8-dipiperazinylquinoline (24), biologically valuable derivatives, were prepared in high yields (82% and 72%, respectively). The synthesized compounds were fully characterizated by H-1 NMR, C-13 NMR, 2D NMR, XRD, HRMS and IR spectra. The novel molecules had effective inhibition profiles against some metabolic enzymes. Also, they have the potential of drug candidates to treat of some diseases including glaucoma, epilepsy, Alzheimer's disease (AD), leukemia, and type-2 diabetes mellitus (T2DM). (C) 2020 Elsevier B.V. All rights reserved.
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    SAR Evaluation of Disubstituted Tacrine Analogues as Promising Cholinesterase and Carbonic Anhydrase Inhibitors
    (Assoc Pharmaceutical Teachers India, 2019) Okten, Salih; Ekiz, Makbule; Tutar, Ahmet; Butun, Burcu; Kocyigit, Umit Muhammet; Topcu, Gulacti; Gulcin, Ilhami
    Background: The inhibition of both hydrolysis products of acetylcholine (ACh), Acetylcholinesterase (AChE) and Butyrylcholinesterase (BChE), is essential for successful treatment of Alzhemier patients. Objectives: This study was investigated inhibition potentials of recently synthesized disubstituted tacrines derivatives on going our research against AChE, BChE and carbonic anhydrase cyctosolic (hCA I and H) enzymes to explore the Structure activity relationship (SAR). Methods: Inhibitory activities of tested compounds against AChE and BChE were measured by spectrophotometric method, developed by Ellman et al. Furthermore, the disubstituted tacrines were determined as inhibitors of two physiologically relevant CA isoforms, the cytosolic hCA I and H by an esterase assay method. Results: The silyl, thiomethyl and cyano substituted seven membered hydrocycle tacrines (9, 11 and 14) significantly inhibited AChE, compared with starting compound 3 (6,8-dibromo-2,3,4,5-teytrahydro-1H-cyclohepta[1,2-b] quinoline) and reference compounds, galantamine and tacrine, while methoxy substituted seven membered hydrocycle tacrine derivative 10 showed selective inhibition against BChE (IC50 = 563 nM). Interestingly, disubstituted tacrines displayed higher or parallel inhibition to galantamine. Additionally, all these tacrine analogues were recorded to be powerful inhibitor compounds of the cytosolic isoenzyme hCA I with K-i in the range of 43.81-471.67 nM, as well as a moderate selectivity toward hCA II isoenzyme with K-i in the range from 87.14 to 614.68 nM compared with AZA, as standard. Conclusion: The disubstituted seven membered hydrocycle tacrine analogues 9-12 and 14 may have promising anti Alzhemier drug candidate and dibromo six membered hydrocycle 2 and dibromo seven membered hydrocycle 3 derivatives may be novel hCA I and II enzyme inhibitors.
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    Synthesis, characterization, crystal structures, theoretical calculations and biological evaluations of novel substituted tacrine derivatives as cholinesterase and carbonic anhydrase enzymes inhibitors
    (Elsevier Science Bv, 2019) Okten, Salih; Ekiz, Makbule; Kocyigit, Umit Muhammet; Tutar, Ahmet; Celik, Ismail; Akkurt, Mehmet; Gulcin, Ilhami
    The six and seven hydrocycle membered disilylanilino acridine (tacrine) analogues (9-11) were synthesized by one-pot procedures. The structures of novel silyl tacrine derivatives were characterized by NMR spectroscopy, elemental analysis and XRD investigations. The silyl substituted novel tacrine derivatives (9-11) were investigated as cholinesterase inhibitors and defined the relative role of AChE (Acetylcholinesterase) versus BChE (Butyrylcholinesterase) inhibition. Novel substituted tacrine derivatives are known as important inhibitors of Carbonic anhydrase (CA) isoenzymes I, and II (hCA I and II), therefore, the synthesized compounds (9-11) were investigated for inhibitory effects on the both CA isoenzymes. Additionally, we evaluated four different enzymes, which were inhibited in the very low nanomolar (nM) range by these compounds. According to the present studies, for AChE, BChE, hCA I and II, the ranges of results are recorded as 30.26 +/- 6.71-117.54 +/- 42.22 nM, 22.45 +/- 5.81-77.41 +/- 4.02 nM, 57.28 +/- 22.16-213.41 +/- 82.75 nM and 46.95 +/- 11.32-274.94 +/- 62.15 nM, respectively. (C) 2018 Elsevier B.V. All rights reserved.