Withanolides and related steroids

Since the isolation of the first withanolides in the mid-1960s, over 600 new members of this group of compounds have been described, with most from genera of the plant family Solanaceae. The basic structure of withaferin A, a C28 ergostane with a modified side chain forming a δ-lactone between carbons 22 and 26, was considered for many years the basic template for the withanolides. Nowadays, a considerable number of related structures are also considered part of the withanolide class; among them are those containing γ-lactones in the side chain that have come to be at least as common as the δ-lactones. The reduced versions (γ and δ-lactols) are also known. Further structural variations include modified skeletons (including C27 compounds), aromatic rings and additional rings, which may coexist in a single plant species. Seasonal and geographical variations have also been described in the concentration levels and types of withanolides that may occur, especially in the Jaborosa and Salpichroa genera, and biogenetic relationships among those withanolides may be inferred from the structural variations detected. Withania is the parent genus of the withanolides and a special section is devoted to the new structures isolated from species in this genus. Following this, all other new structures are grouped by structural types. Many withanolides have shown a variety of interesting biological activities ranging from antitumor, cytotoxic and potential cancer chemopreventive effects, to feeding deterrence for several insects as well as selective phytotoxicity towards monocotyledoneous and dicotyledoneous species. Trypanocidal, leishmanicidal, antibacterial, and antifungal activities have also been reported. A comprehensive description of the different activities and their significance has been included in this chapter. The final section is devoted to chemotaxonomic implications of withanolide distribution within the Solanaceae. Overall, this chapter covers the advances in the chemistry and biology of withanolides over the last 16 years.Fil: Misico, Rosana Isabel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos Aplicados a la Química Orgánica (i); ArgentinaFil: Nicotra, V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; ArgentinaFil: Oberti, Juan Carlos María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; ArgentinaFil: Barboza, Gloria Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; ArgentinaFil: Gil, Roberto Ricardo. University Of Carnegie Mellon; Estados UnidosFil: Burton, Gerardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos Aplicados a la Química Orgánica (i); Argentin

Amyloid-beta fibril disruption by C60-molecular guidance for rational drug design

The WHO has listed Alzheimer's disease among the major neurological disorders with an estimated 35 million people affected worldwide. Amyloid-beta is mostly believed to be the causative factor in Alzheimer's disease and the severity of the disease correlates with the tendency of amyloid-beta to form aggregation patterns-plaques. Lacking effective medication, the identification of any underlying mechanistic principles regarding plaque formation appears to be crucial. Here we carry out computer simulations to study the effect of C-60 on structure and stability of an idealised pentameric construct of amyloid-beta units (a model fibril). A binding site on top of the structurally ordered stack of beta-sheets is identified that triggers structural alterations at the turn region of the hook-like beta-sheet assembly. Significant structural alterations are: (i) the destruction of regular helical twist, (ii) the loss of a stabilizing salt bridge and (iii) the loss of a stabilizing hydrophobic interaction close to the turn. Consequently, the main effect of C-60 is the induction of sizable destabilization in native fibril structure. These structural insights may serve as a molecular guide for further rational drug design of effective inhibitors targeting fibril formation in Alzheimer's disease

Study of the Cytotoxic and Antifungal Activities of Neolignans 8.O.4´ and Structurally Related Compounds

In the present work we report the antifungal and cytotoxic activities of a neolignan 8.O.4´series. The most active antifungal compounds show a significant cytotoxic effect which might be related

Antimicrobial activity of aqueous extracts and of berberine isolated from Berberis heterophylla

Fil: Freile, M. L. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales; Chubut, Argentina.Fil: Giannini, F. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina.Fil: Pucci, G. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales; Chubut, Argentina.Fil: Sturniolo, A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Rodero, L. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Pucci, O. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Balzareti, V. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales; Chubut, Argentina.Fil: Enriz, R. D. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina.The antimicrobial activity of Berberis heterophylla leaves, stems and root aqueous extracts was studied in vitro on Gram-positive and Gram-negative bacteria and fungi. The in vitro antifungal activity of berberine isolated from the same source against different Candida species was also investigated

In vitro antifungal evaluation and structure-activity relationships of a new series of chalcone derivatives and synthetic analogues, with inhibitory properties against polymers of the fungal cell wall.

[EN]Here we report the synthesis, in vitro antifungal evaluation and SAR study of 41 chalcones and analogues. In addition, all active structures were tested for their capacity of inhibiting Saccharomyces cerevisiae beta(1,3)-glucan synthase and chitin synthase, enzymes that catalyze the synthesis of the major polymers of the fungal cell wall. Compounds of the general structure 1 were synthesized and examined or their antifungal properties with cellular and enzymatic assays. Many chalcone derivatives displayed potent activites against dermatophytes. A structure–activity relationship (SAR) study supported by theoretical calculations aided to identify the minimal structual requeriments for the antifungal action. Regarding the mode of action, all active structures inhibited β(1,3)-glucan synthase and mainly chitin synthase-1, enzymes that catalyze the synthesis of the two majors polymers of the fungal cell wall.SAZ (Agencia de Promociones Cientı́ficas y Tecnológicas de la Argentina), SNL, RDE (Univ. Nac. San Luis), Iberoamerican Project PIBEAFUN, Iberoamerican Program of Science and Technology for the Development (CYTED

Exploration of the full conformational space of N-acetyl-L-glutamate-N-methylamide

A conformational and electronic study on N-acetyl-L-glutamate-N-methylamide was carried out. Theoretical computational analysis revealed 21 different conformations at the RB3LYP/6-31G(d) level of theory. Ab initio calculations at two levels of theory (RHF/3-21G and RHF/6-31G(d)) were also performed. All side-chain conformations were explored for this compound. N-acetyl-L-glutamate-N-methylamide displayed a different conformational behaviour in comparison with other amino acids possessing shorter side-chains. These results can be attributed, at least in part, to the side-chain-backbone interactions, which are stabilizing the low-energy conformations in this molecule