Development of novel small-size peptides as putative therapeutic drugs

This thesis focuses on the development of small peptide molecules with either antifungal properties or with the ability to control protein deposits that cause the characteristic brain damage in Alzheimer's disease (AD). Thus, our ultimate aim is to design putative therapeutic agents supported by computational techniques. Apropos of AD, this is a very complex disease where brain damage is associated with the degradation of the human mind and memory. Currently, researchers consent that a key role is played by a peptide called beta-amyloid. This peptide is not toxic by itself, however it becomes toxic to nerve-cells when several of its molecules clump together forming aggregates. This is the beginning of a slow but unstoppable brain deterioration, which ultimately leads to dementia. The currently available AD drugs delay, at best, the loss of memory, but do not stop the neural degradation. Its severity and the increasing number of AD patients, are the worldwide driving force to acquire more effective drugs. In our own research we focused on the development of new peptides that prevent or slow down the formation of the aggregated beta-amyloid. Computational techniques allowed us to explore the self-bound beta-amyloid molecules, as well as their interaction with new potential drugs. With this fascinating information we designed small peptides aimed at disrupting the aggregated beta-amyloid. Then, its anti-amyloid activity of was tested in vitro and in vivo. Both tests have produced not only positive but also striking and promising results indicating the potential therapeutic application of these new anti-amyloid peptides.

Structure of isolated tyrosyl-glycyl-glycine tripeptide. A comparative conformational study with peptides containing an aromatic ring

The potential energy surface (PES) of tyrosyl-glycyl-glycine (YGG) tripeptide in solution was explored using EDMC (Electrostatically Driven Monte Carlo) and in the gas-phase by means of ab initio quantum chemical calculations. The theoretical computational analysis revealed that this tripeptide possesses a significant molecular flexibility. A C7 backbone conformation was the most energetically preferred for the central Gly residue, using both methodologies. Some new stable conformers that have not been previously reported were identified in the gas phase as well. This study points out the interplay of backbone and side-chain contributions in determining the relative stabilities of energy minima. In addition, the peptide backbone of YGG was compared with other small peptides containing aromatic side-chains (Phe-Gly-Gly and Trp-Gly-Gly). The comparison with experimental X-ray results was also satisfactory.Fil: Barrera Guisasola, Exequiel Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Masman, Marcelo Fabricio. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Rodríguez, Ana M.. Universidad Nacional de San Luis; Argentin

Zoledronate Derivatives as Potential Inhibitors of Uridine Diphosphate-Galactose Ceramide Galactosyltransferase 8:A Combined Molecular Docking and Dynamic Study

Krabbe's disease is a neurodegenerative disorder caused by deficiency of galactocerebrosidase activity that affects the myelin sheath of the nervous system, involving dysfunctional metabolism of sphingolipids. It has no cure. Because substrate inhibition therapy has been shown to be effective in some human lysosomal storage diseases, we hypothesize that a substrate inhibition therapeutic approach might be appropriate to allow correction of the imbalance between formation and breakdown of glycosphingolipids and to prevent pathological storage of psychosine. The enzyme responsible for the biosynthesis of galactosylceramide and psychosine is uridine diphosphate-galactose ceramide galactosyltransferase (2-hydroxyacylsphingosine 1-b-galactosyltransferase; UGT8; EC 2.4.1.45), which catalyzes the transferring of galactose from uridine diphosphate-galactose to ceramide or sphingosine, an important step of the biosynthesis of galactosphingolipids. Because some bisphosphonates have been identified as selective galactosyltransferase inhibitors, we verify the binding affinity to a generated model of the enzyme UGT8 and investigate the molecular mechanisms of UGT8-ligand interactions of the bisphosphonate zoledronate by a multistep framework combining homology modeling, molecular docking, and molecular dynamics simulations. From structural information on UGTs' active site stereochemistry, charge density, and access through the hydrophobic environment, the molecular docking procedure allowed us to identify zoledronate as a potential inhibitor of human ceramide galactosyltransferase. More importantly, zoledronate derivates were designed through computational modeling as putative new inhibitors. Experiments in vivo and in vitro have been planned to verify the possibility of using zoledronate and/or the newly identified inhibitors of UGT8 for a substrate inhibition therapy useful for treatment of Krabbe's disease and/or other lysosomal disorders

Dynamic function of the Alkyl spacer of acetogenins as potent inhibitors of mitochondrial complex I: a molecular dynamics simulation approach

Acetogenins are among the most potent of the known inhibitors of complex I (NADH-ubiquinone oxidoreductase) in mitochondrial electron transfer system. Elucidation of the dynamic function of the alkyl spacer linking the two toxophores (i.e., the hydroxylated tetrahydrofuran and the γ-lactone rings) is critical for fully understanding their inhibition mechanism. To this end, using molecular dynamics simulations a structure-activity relationship study of a series of acetogenins was performed for the first time using this approach. Our results clearly indicated that both, the length and the molecular flexibility of the spacer, were crucial for taking an active conformation. A partially folded conformation with an optimal length (bis-tetrahydrofuran rings and 13 carbon atoms) of about 16 Å with a high molecular flexibility might depict an active form of the spacer. In addition, we demonstrated that the bis-tetrahydrofuran derivatives are able to overcome the shortage of the length of the spacer more efficiently than the mono-tetrahydrofuran derivatives with the help of the additional tetrahydrofuran, which acts as a pseudospacer. Our results obtained from molecular dynamics calculations supported the use of a combined decane/water system as a good solvent model to simulate the biological environment of acetogenins acting as inhibitor of complex I.Fil: Bombasaro, José Abel. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; ArgentinaFil: Barrera Guisasola, Exequiel Ernesto. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Masman, Marcelo Fabricio. University of Groningen; Países Bajos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodríguez, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; Argentin

Catalytic and molecular properties of rabbit liver carboxylesterase acting on 1,8-cineole derivatives

Rabbit liver carboxylesterase (rCE) was evaluated as the catalyst for the enantioselective hydrolysis of (±)-3-endo-acetyloxy-1,8-cineole [(±)-4], which yields (1S,3S,4R)-(+)-3-acetyloxy-1,8-cineole [(+)-4] and (1R,3R,4S)-(-)-3-hydroxy-1,8-cineole [(-)-3]. Enantioselective asymmetrization of meso-3,5-diacetoxy- 1,8-cineol (5) gives (1S,3S,4R,5R)-(-)-3-acetyloxy-5- hydroxy-1,8-cineole (6), with high enantioselectivity. rCE has been chosen to perform both experiments and molecular modeling simulations. Docking simulations combined with molecular dynamics calculations were used to study rCE-catalyzed enantioselective hydrolysis of cineol derivatives. Both compounds were found to bind with their acetyl groups stabilized by hydrogen bond interactions between their oxygen atoms and Ser221.Fil: Loandos, Maria del Huerto. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Muro, Ana Carolina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Villecco, Margarita Beatriz. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Orgánica; ArgentinaFil: Masman, Marcelo Fabricio. University of Groningen; Países Bajos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis; ArgentinaFil: Luiten, Paul G. M.. University of Groningen; Países BajosFil: Andujar, Sebastian Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Suvire, Fernando Daniel. Universidad Nacional de San Luis; ArgentinaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentin

Aromatization within the putative bio-medical action mechanism of berberine and related cationic alkaloids with double iso-quinolinoid skeleton. A theoretical study

In the putative mechanism of action for berberin, to prevent DNA replication the first step is aromatization. The aromatizaion process, via dehydrogenation has been studied for a series of compounds related to berberine. In contrast to the covalent dehydrogenation, which is endothermic, the aromatization under ionic conditions was found to be exothermic. The availability of the hydride for ionic aromatization was indicated by the effective HOMO of berberine and related compounds. The results indicate that in the aromatization process the ease of hydride ion removal parallels the stabilizations energy of the aromatic compounds to be formed. Comparing the nucleophilic additions to the π-system, the LUMO energy values suggested a greater accessibility of the N(+) heterocycles in comparison to the polycycle aromatic hydrocarbons.Fil: Freile, Monica Liliana. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Masman, Marcelo Fabricio. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Suvire, Fernando Daniel. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zacchino, Susana Alicia Stella. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Balzaretti, Vilma Teresa. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentin

Synthesis and conformational analysis of His-Phe-Arg-Trp-NH2 and analogues with antifungal properties

The synthesis, in vitro evaluation, and conformational study of His-Phe-Arg-Trp-NH2 and related derivatives acting as antifungal agents are reported. Among them, His-Phe-Arg-Trp-NH2 and His-Tyr-Arg-Trp-NH2 exhibited antifungal activity against Cryptococcus neoformans. Antifungal activity of these compounds appears to be closely related to the α-MSH effect. A conformational and electronic study allows us to propose a biologically relevant conformation for these tetrapeptides acting as antifungal agents. In addition, these theoretical calculations permit us to determine the minimal structural requirements to produce the antifungal response and may provide a guide for the design of compounds with this biological activity.Fil: Masman, Marcelo Fabricio. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodriguez, Ana Maria. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Svetaz, Laura Andrea. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zacchino, Susana Alicia Stella. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; ArgentinaFil: Somlai, Csaba. Szegedi Tudományegyetem; HungríaFil: Csizmadia, Imre Gyula. Szegedi Tudományegyetem; HungríaFil: Penke, Botond. Szegedi Tudományegyetem; HungríaFil: Enriz, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentin