Publications (40) View all
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Article: Tacrine-silibinin codrug shows neuro- and hepatoprotective effects in vitro and pro-cognitive and hepatoprotective effects in vivo.
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ABSTRACT: A codrug of the anti-Alzheimer drug tacrine and the natural product silibinin was synthesized. The codrug's biological and pharmacological properties were compared to an equimolar mixture of the components. The compound showed potent acetyl- and butyrylcholinesterase inhibition. In a cellular hepatotoxicity model, analyzing the influence on viability and mitochondria of hepatic stellate cells (HSC), the toxicity of the codrug was markedly reduced in comparison to that of tacrine. Using a neuronal cell line (HT-22), a neuroprotective effect against glutamate-induced toxicity could be observed that was absent for the 1:1 mixture of components. In subsequent in vivo experiments in rats, in contrast to the effects seen after tacrine treatment, after administration of the codrug no hepatotoxicity and no induction of the cytochrome P450 system were noticed. In a scopolamine-induced cognitive impairment model using Wistar rats, the codrug was as potent as tacrine in reversing memory dysfunction. The tacrine-silibinin codrug shows high AChE and BChE inhibition, neuroprotective effects, lacks tacrine's hepatotoxicity in vitro and in vivo, and shows the same pro-cognitive effects in vivo as tacrine, being superior to the physical mixture of tacrine and silibinin in all these regards.Journal of Medicinal Chemistry 05/2012; 55(11):5231-42. · 4.80 Impact Factor -
Article: Mycobacterium tuberculosis and cholinesterase inhibitors from Voacanga globosa.
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ABSTRACT: Globospiramine (1), a new spirobisindole alkaloid possessing an Aspidosperma-Aspidosperma skeleton, together with deoxyvobtusine (2), deoxyvobtusine lactone (3), vobtusine lactone (4) and lupeol (5), were isolated and identified from Voacanga globosa through a bioassay-guided purification. The gross structure and absolute stereochemistry of 1 were established by circular dichroism spectroscopy, HR-MS and unambiguous NMR spectroscopic experiments. In addition, a new biogenetic pathway for the formation of the spiro-Aspidosperma-Aspidosperma skeleton is proposed. Alkaloid 1 showed potent antituberculosis activity against Mycobacterium tuberculosis H(37)Rv as evidenced in microplate Alamar blue assay (MIC = 4 μg/mL) and low-oxygen recovery assay (LORA (MIC = 5.2 μg/mL). The bisindole alkaloids also exhibited promising activity against acetylcholinesterase and, especially butyrylcholinesterase, with deoxyvobtusine (2) (IC(50) = 6.2 μM) as the most strongly inhibiting compound. This study extends the variety of alkaloid structural platforms which exhibit antimycobacterial and anticholinesterase activity.European journal of medicinal chemistry 07/2011; 46(7):3118-23. · 3.27 Impact Factor -
Article: Probing the mid-gorge of cholinesterases with spacer-modified bivalent quinazolinimines leads to highly potent and selective butyrylcholinesterase inhibitors.
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ABSTRACT: The spacer structure of homobivalent quinazolinimes acting as potent acetyl-(AChE)- and butyrylcholinesterase (BChE) inhibitors was chemically modified introducing tertiary amine and acyl-amide moieties, and the activities at both ChEs were evaluated. Molecular docking was applied to explain the data and probe the capacity of the mid-gorge site of both ChEs. The novel spacer structures considerably alter the biological profile of bivalent quinazolinimines with regard to both inhibitory activity and selectivity. Mutual interaction of binding to the various sites of the enzymes was further investigated by applying also different spacer lengths and ring sizes of the alicycle of the tricyclic quinazolinimines. In order to achieve selectivity toward BChE and to improve inhibitory activities, the spacer structure was optimized and identified a highly potent and selective BChE inhibitor.Bioorganic & medicinal chemistry 02/2011; 19(3):1222-35. · 2.82 Impact Factor -
Article: Cardioprotective effect of NO-metoprolol in murine coxsackievirus B3-induced myocarditis.
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ABSTRACT: The effect of NO-metoprolol, that is, 3-nitrooxypivaloyl metoprolol-amide, a novel NO-releasing derivative of the β1-blocking drug metoprolol was investigated in A.CA/SnJ mice infected with coxsackievirus B3 (CVB3) and compared to metoprolol and placebo. Daily treatment of mice with the respective drug started immediately (experiment A) or 3 days after virus infection (experiment B) and was continued until day 13 post-infection (p.i.). Two doses of NO-metoprolol were administered. Body mass differences, viral load, and histopathological signs of myocarditis were compared between the several groups. As a result, NO-metoprolol diminished significantly the body weight loss, the viral load and the histopathology, whereas metoprolol treatment led solely to a significant attenuation of myocardial damage. In experiment A, low dose NO-metoprolol decreased significantly enteroviral copy numbers. Both doses of NO-metoprolol had a significant effect on reduction of myocardial infiltrates and fibrosis. The data suggest that delayed drug administration might more advantageous. Both doses of NO-metoprolol reduced significantly the scores of four tested parameters compared to placebo. Body weight loss, virus titers, plus-strand as well as minus-strand enteroviral RNA levels, infiltration and fibrosis scores were diminished significantly when NO-metoprolol was given 3 days p.i. In addition, a significant difference regarding the enteroviral copy numbers was observed between low dose NO-metoprolol- and metoprolol-treated mice. Treatment with metoprolol reduced insignificantly the viral load and body weight loss (experiment A and B) but led to a significant reduction of myocardial histopathology in experiment A. The results indicate that NO-metoprolol treatment has a greater therapeutic benefit than metoprolol.Journal of Medical Virology 12/2010; 82(12):2043-52. · 2.82 Impact Factor -
Article: Bivalent 5,8,9,13b-tetrahydro-6H-isoquino[1,2-a]isoquinolines and -isoquinolinium salts: novel heterocyclic templates for butyrylcholinesterase inhibitors.
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ABSTRACT: Three different types of homobivalent compounds, 5,8,9,13b-tetrahydro-6H-isoqino[1,2-a]isoquinolines bearing tertiary N-atoms, their quaternary ammonium salts and their dibenzazecine analogues, connected by alkylene spacers of various lengths were synthesized. Compared to the therapeutically used inhibitor galanthamine, some of the bivalent compounds showed much higher inhibitory activities at both cholinesterases in the Ellman test. Surprisingly, not only the quaternary salts, but also the uncharged tertiary compounds exhibited IC(50) values at butyrylcholinesterase in the nanomolar range. Selectivity toward BChE of up to 76-fold was observed.Bioorganic & medicinal chemistry letters 03/2010; 20(9):2946-9. · 2.65 Impact Factor
