- Antischistosomal Activity of Pyrido[1,2-a]benzimidazole Derivatives and Correlation with Inhibition of β-Hematin Formation
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The extensive use of praziquantel against schistosomiasis raises concerns about drug resistance. New therapeutic alternatives targeting critical pathways within the parasite are therefore urgently needed. Hemozoin formation in Schistosoma presents one such target. We assessed the in vitro antischistosomal activity of pyrido[1,2-a]benzimidazoles (PBIs) and investigated correlations with their ability to inhibit β-hematin formation. We further evaluated the in vivo efficacy of representative compounds in experimental mice and conducted pharmacokinetic analysis on the most potent. At 10 μM, 48/57 compounds resulted in >70% mortality of newly transformed schistosomula, whereas 37 of these maintained >60% mortality of adult S. mansoni. No correlations were observed between β-hematin inhibitory and antischistosomal activities against both larval and adult parasites, suggesting possible presence of other target(s) or a mode of inhibition of crystal formation that is not adequately modeled by the assay. The most active compound in vivo showed 58.7 and 61.3% total and female worm burden reduction, respectively. Pharmacokinetic analysis suggested solubility-limited absorption and high hepatic clearance as possible contributors to the modest efficacy despite good in vitro activity. The PBIs evaluated in this report thus merit further optimization to improve their efficacy and to elucidate their possible mode of action.
- Okombo, John,Singh, Kawaljit,Mayoka, Godfrey,Ndubi, Ferdinand,Barnard, Linley,Njogu, Peter M.,Njoroge, Mathew,Gibhard, Liezl,Brunschwig, Christel,Vargas, Mireille,Keiser, Jennifer,Egan, Timothy J.,Chibale, Kelly
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p. 411 - 420
(2017/06/14)
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- Antimalarial benzoheterocyclic 4-aminoquinolines: Structure-activity relationship, in vivo evaluation, mechanistic and bioactivation studies
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A novel class of benzoheterocyclic analogues of amodiaquine designed to avoid toxic reactive metabolite formation was synthesized and evaluated for antiplasmodial activity against K1 (multidrug resistant) and NF54 (sensitive) strains of the malaria parasite Plasmodium falciparum. Structure-activity relationship studies led to the identification of highly promising analogues, the most potent of which had IC50s in the nanomolar range against both strains. The compounds further demonstrated good in vitro microsomal metabolic stability while those subjected to in vivo pharmacokinetic studies had desirable pharmacokinetic profiles. In vivo antimalarial efficacy in Plasmodium berghei infected mice was evaluated for four compounds, all of which showed good activity following oral administration. In particular, compound 19 completely cured treated mice at a low multiple dose of 4 × 10 mg/kg. Mechanistic and bioactivation studies suggest hemozoin formation inhibition and a low likelihood of forming quinone-imine reactive metabolites, respectively.
- Ongarora, Dennis S.B.,Strydom, Natasha,Wicht, Kathryn,Njoroge, Mathew,Wiesner, Lubbe,Egan, Timothy J.,Wittlin, Sergio,Jurva, Ulrik,Masimirembwa, Collen M.,Chibale, Kelly
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p. 5419 - 5432
(2015/11/11)
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- Benzoheterocyclic amodiaquine analogues with potent antiplasmodial activity: Synthesis and pharmacological evaluation
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The synthesis and evaluation of antiplasmodial activity of benzothiazole, benzimidazole, benzoxazole and pyridine analogues of amodiaquine is hereby reported. Benzothiazole and benzoxazole analogues with a protonatable tertiary nitrogen atom possessed excellent activity against the W2 and K1 chloroquine resistant strains of Plasmodium falciparum, with IC50s ranging from 7 to 22 nM.
- Ongarora, Dennis S.B.,Gut, Jiri,Rosenthal, Philip J.,Masimirembwa, Collen M.,Chibale, Kelly
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p. 5046 - 5050
(2012/09/07)
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- NOVEL MCH RECEPTOR ANTAGONISTS
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The present invention relates to a melanin concentrating hormone antagonist compound of formula (I); wherein Ar1, L1, R1, q, X, R2, R3, R4, and R5 are as defined, or a pharmaceutically acceptable salt, solvate, or enantiomer thereof useful in the treatment, prevention or amelioration of symptoms associated with obesity and related diseases.
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Page/Page column 47-48
(2008/06/13)
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- Benzothiazole, thiazolopyridine, benzooxazole and oxazolopyridine derivatives
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This invention is concerned with compounds of the formula wherein A, B1, B2, R1, R2 and G are as defined in the description and claims, and pharmaceutically acceptable salts thereof. The invention further relates to pharmaceutical compositions containing such compounds, to a process for their preparation and to their use for the treatment and/or prevention of diseases which are associated with the modulation of SST receptors subtype 5.
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Page/Page column 56
(2010/11/23)
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- Pharmaceutical compositions for CNS and other disorders
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The present invention relates to a method of treating disorders of the Central Nervous System (CNS) and other disorders in a mammal, including a human, by administering to the mammal a CNS-penetrant α7 nicotinic receptor agonist. It also relates to pharmaceutical compositions containing a pharmaceutically acceptable carrier and a CNS-penetrant α7 nicotinic receptor agonist.
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- The vicarious nucleophilic substitution of hydrogen and related reactions in nitrobenzoxazoles
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5- and 6-nitrobenzoxazoles 3 and 4 react with nucleophiles exclusively at C-2, giving ring opening products. If position 2- is blocked with phenyl substituent the reaction takes place in the carbocyclic ring affording the VNS products. 2-Methylthio-5-nitrobenzoxazole 7 and its 6-nitro isomer 8 give products which result from addition of a nucleophile to the carbocyclic ring (VNS) as well as to the heterocyclic ring (S(N)Ar and ring cleavage). 2-Methylthiobenzoxazoles can be readily converted to the corresponding benzoxazolones via oxidative hydrolysis.
- Makosza, Mieczyslaw,Stalewski, Jacek
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p. 7277 - 7286
(2007/10/02)
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