Browsing by Subject "Dose-Response Relationship, Drug"
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Item Open Access Application of the Ugi reaction with multiple amino acid-derived components: Synthesis and conformational evaluation of piperazine-based minimalist peptidomimetics(Royal Society of Chemistry, 2015) Stucchi, M.; Cairati, S.; Cetin-Atalay, R.; Christodoulou, M.S.; Grazioso G.; Pescitelli G.; Silvani, A.; Yildirim, D.C.; Lesma G.The concurrent employment of α-amino acid-derived chiral components such as aldehydes and α-isocyanoacetates, in a sequential Ugi reaction/cyclization two-step strategy, opens the door to the synthesis of three structurally distinct piperazine-based scaffolds, characterized by the presence of l-Ala and/or l-Phe-derived side chains and bearing appropriate functionalities to be easily applied in peptide chemistry. By means of computational studies, these scaffolds have been demonstrated to act as minimalist peptidomimetics, able to mimic a well defined range of peptide secondary structures and therefore potentially useful for the synthesis of small-molecule PPI modulators. Preliminary biological evaluation of two different resistant hepatocellular carcinoma cellular lines, for which differentiation versus resistance ability seem to be strongly correlated with well defined types of PPIs, has revealed a promising antiproliferative activity for selected compounds. © The Royal Society of Chemistry 2015.Item Open Access Behavioural analyses of quinine processing in choice, feeding and learning of larval drosophila(2012) El-Keredy, A.; Schleyer, M.; König, C.; Ekim, A.; Gerber, B.Gustatory stimuli can support both immediate reflexive behaviour, such as choice and feeding, and can drive internal reinforcement in associative learning. For larval Drosophila, we here provide a first systematic behavioural analysis of these functions with respect to quinine as a study case of a substance which humans report as "tasting bitter". We describe the dose-effect functions for these different kinds of behaviour and find that a half-maximal effect of quinine to suppress feeding needs substantially higher quinine concentrations (2.0 mM) than is the case for internal reinforcement (0.6 mM). Interestingly, in previous studies (Niewalda et al. 2008, Schipanski et al 2008) we had found the reverse for sodium chloride and fructose/sucrose, such that dose-effect functions for those tastants were shifted towards lower concentrations for feeding as compared to reinforcement, arguing that the differences in dose-effect function between these behaviours do not reflect artefacts of the types of assay used. The current results regarding quinine thus provide a starting point to investigate how the gustatory system is organized on the cellular and/or molecular level to result in different behavioural tuning curves towards a bitter tastant. © 2012 El-Keredy et al.Item Open Access Synthesis and anticancer activity evaluation of some benzothiazole-piperazine derivatives(Bentham Science Publishers B.V., 2015) Gurdal, E.E.; Buclulgan, E.; Durmaz I.; Cetin-Atalay, R.; Yarim, M.Synthesis, characterization and cytotoxic activities of ten benzothiazole-piperazine derivatives were reported. In vitro cytotoxic activities of compounds were screened against hepatocellular (HUH-7), breast (MCF-7) and colorectal (HCT-116) cancer cell lines by sulphorhodamine B assay. Based on the GI50 values of the compounds, most of the benzothiazole-piperazine derivatives are active against HUH-7, MCF-7 and HCT-116 cancer cell lines. Aroyl substituted compounds 1h and 1j were found to be the most active derivatives. In addition, further investigation of compounds 1h and 1j by Hoechst staining and FACS revealed that these compounds cause apoptosis by cell cycle arrest at subG1 phase. © 2015 Bentham Science Publishers.Item Open Access Synthesis of novel substituted purine derivatives and identification of the cell death mechanism(Elsevier Masson SAS, 2015) Demir, Z.; Guven, E.B.; Ozbey, S.; Kazak, C.; Atalay, R.C.; Tuncbilek, M.Novel substituted adenine and purine derivatives were designed and synthesized.Compound 36 displayed the greatest cytotoxic activity with IC50 less than 1 1/4M.36 induces senescence associated cell death, which was demonstrated with SA2-Gal assay. © 2014 Elsevier Masson SAS.