Synthesis of analogs of marine sulfated steroids with cytotoxic, antiviral and acetylcholinesterase enzyme inhibition activities

En este trabajo de tesis se describe la síntesis de diferentes análogos de esteroidessulfatados marinos con el objeto de evaluar su actividad biológica y establecer correlacionesestructura-actividad. Los esteroides sintetizados poseen grupos sulfato en C-2 y C-3 condiferentes configuraciones y funciones oxigenadas en C-6 y fueron obtenidos a partir de lasulfatación de sus análogos hidroxilados. La reacción de sulfatación fue optimizada luego deprobar diferentes condiciones, entre ellas, la selección del agente sulfatante, la relación deequivalentes entre el esteroide y el agente sulfatante, el tiempo y la temperatura dereacción y el método de calentamiento. Todos los análogos sintéticos se obtuvieron a partirde un precursor común, la 5α-colest-2-en-6-ona, que se sintetizó mediante sucesivasreacciones de oxidación y reordenamientos a partir del colesterol. Se ensayó la actividad de inhibición de la enzima acetilcolinesterasa de los compuestossulfatados y sus análogos hidroxilados y se observó que el compuesto 2β,3α-dihidroxi-5α-colestan-6-ona disulfato resultó ser el más activo de la serie. Por ello, este compuesto fue elelegido como modelo para el estudio de la cinética de la reacción de inhibición. En base a lacinética de la reacción, se realizó un estudio de docking molecular del compuesto y de suanálogo desulfatado, el cual no inhibe a la enzima acetilcolinesterasa. Luego se realizaronestudios de dinámica molecular verificándose la estabilidad de los complejos enzimaesteroideobtenidos en el estudio de docking. En el caso del análogo inactivo, si bien secomprobó la estabilidad del complejo, se observó la apertura de un canal secundario en lasuperficie de la enzima que comunica con el sitio activo, lo que explicaría la razón por la quedicho esteroide no inhibe a la enzima. Debido a los antecedentes de citotoxicidad de los 6E-hidroximino esteroides, sesintetizaron cuatro oximas novedosas a partir de los correspondientes 6-cetoesteroidesobtenidos previamente. Se estudió la citotoxicidad de las oximas sintéticas y de algunosesteroides polihidroxilados sulfatados relacionados -para evaluar la influencia de gruposhidroxilo, sulfato y carbonilo en C-6 en la actividad- frente a dos líneas celulares tumoralesde cáncer de próstata humano, PC-3 (andrógeno independiente) y LNCaP (andrógenodependiente). Los resultados indicaron que el compuesto 2β,3α,6β-trihidroxi-5α-colestanotrisulfato fue el más activo frente a la línea celular LNCaP y la oxima 2β,3α-dihidroxi-6E-hidroximino- 5α-colestano, frente a PC-3. Por último, se estudió la actividad antiviral y virucida de los compuestos sulfatados y susanálogos desulfatados frente a los virus herpes simplex tipo 1 (HSV-1) y Junín (JV),responsable de la fiebre hemorrágica argentina. La oxima 2β,3α-dihidroxi-6E-hidroximino- 5α-colestano resultó ser el compuesto más activo frente al virus HSV-1, mientras que loscompuestos 2β,3α-dihidroxi-5α-colestan-6-ona disulfato y 2β,3α,6β-trihidroxi-5α-colestano- 2,3-disulfato fueron los más activos frente al virus Junín. Ambos resultados ponen demanifiesto la importancia de los grupos sulfato para la actividad antiviral de estosesteroides.In this work we describe the synthesis of analogs of marine sulfated steroids in orderto evaluate their biological activities and establish structure-activity correlations. Thesynthesized steroids depict sulfate groups at C-2 and C-3 with different configurations andoxygenated groups at C-6, and they were obtained by sulfation of their hydroxylatedanalogs. The sulfation reaction was optimized after selecting the sulfating agent, the relativeproportions between steroid and sulfating agent, the reaction time and the heatingconditions. The synthetic analogs were prepared from 5α-cholest-2-en-6-one, which wassynthesized from cholesterol by successive oxidation and rearrangement reactions. The sulfated and desulfated analogs were evaluated for their inhibition activity onthe acetylcholinesterase enzyme. Compound 2β,3α-dihydroxy-5α-cholestan-6-one disulfateproved to be the more active. Therefore it was selected as a model compound to study thekinetic of the inhibition reaction. Based on the kinetic results, a molecular docking study ofthe compound and the inactive desulfated analog was performed, together with dynamicmolecular studies that confirmed the stability of the enzyme-steroid complexes obtained inthe docking study. Although the inactive analog complex was stable, we observed theopening of a secondary channel on the enzyme surface that communicates with the activesite. This fact would explain why the desulfated steroid fails to inhibit the enzyme. Taking into account the cytotoxic activities of 6E-hydroximino steroids, we preparedfour new oximes of the 6-ketosteroids previously synthesized. We evaluated the cytotoxicityof the synthetic oximes and some related sulfated polyhydroxylated steroids on two humanprostate carcinoma cell lines, PC-3 (androgen independent) and LNCaP (androgendependent) in order to determine the influence of hydroxyl, sulfate and carbonyl groups on C-6 on the activity. Compound 2β,3α,6β-trihydroxy-5α-cholestane trisulfate showedremarkable activity against LNCaP cell line while oxime 2β,3α-dihydroxy-6E-hydroxymino- 5α-cholestane was the most active against PC-3. We also studied the antiviral and virucidal activities of the sulfated compounds and theirdesulfated analogs against herpes simplex virus type 1 (HSV-1) and Junín virus (JV),responsible for the argentine hemorrhagic fever. The oxime 2β,3α-dihydroxy-6E-hydroxymino- 5α-cholestane disulfate was the most active compound against HSV-1, whilecompounds 2β,3α-dihydroxy-5α-cholestan-6-one disulfate and 2β,3α,6β-trihydroxy-5α-cholestane-2,3-disulfate were the most active against Junín virus. These results highlight theimportance of the sulfate groups for the activity of these steroids.Fil: Richmond, Victoria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Oxidation at C-16 enhances butyrylcholinesterase inhibition in lupane triterpenoids

A set of triterpenoids with different grades of oxidation in the lupane skeleton were prepared and evaluated as cholinesterase inhibitors. Allylic oxidation with selenium oxide and Jones’s oxidation were employed to obtain mono-, di- and tri-oxolupanes, starting from calenduladiol (1) and lupeol (3). All the derivatives showed a selective inhibition of butyrylcholinesterase over acetylcholinesterase (BChE vs. AChE). A kinetic study proved that compounds 2 and 9, the more potent inhibitors of the series, act as competitive inhibitors. Molecular modeling was used to understand their interaction with BChE, the role of carbonyl at C-16 and the selectivity towards this enzyme over AChE. These results indicate that oxidation at C-16 of the lupane skeleton is a key transformation in order to improve the cholinesterase inhibition of these compounds.Fil: Castro, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Richmond, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Faraoni, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Murray, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Knowledge and Beliefs Associated with Environmental Health Literacy: A Case Study Focused on Toxic Metals Contamination of Well Water

Environmental health literacy (EHL) is developing as a framework that can inform educational interventions designed to facilitate individual and collective action to protect health, yet EHL measurement poses several challenges. While some studies have measured environmental health knowledge resulting from interventions, few have incorporated skills and self-efficacy. In this study, a process-focused EHL instrument was developed, using the Newest Vital Sign (NVS) health literacy instrument as a model and tailoring it for the context of private well contamination with toxic metals. Forty-seven (47) participants, including undergraduate students and residents of communities with contaminated well water, piloted a prototype EHL instrument alongside NVS. Results suggested a moderate degree of correlation between NVS and the EHL prototype, and significant differences in scores were observed between students and residents. Responses to a self-efficacy survey, tailored for drinking water contaminated with arsenic, revealed significant differences between students and residents on items related to cost and distance. In response to open-ended questions, participants identified a range of potential environmental contaminants in drinking water and deemed varied information sources as reliable. This study highlights differences in knowledge and self-efficacy among students and residents and raises questions about the adequacy of EHL assessments that mimic formal education approaches

The use of non-invasive measures to predict thermal strain: How accurate are universal models?

Over the past few decades there has been an upsurge in the development of monitoring devices that estimate levels of thermal strain non-invasively. However, developing a non-invasive monitoring device that estimates body core temperature (Tc) with a certain level of accuracy that is satisfactory over multiple heat stress scenarios and a wide range of body core temperatures has been shown to be a difficult task [1]. The aim of this study was to investigate the potential of using a combination of simple non-invasive measures to estimate rectal temperature (Tre) (used as a reference for Tc) over multiple types of heat stress scenarios within a varied population

Liberation of Recalcitrant Cell Wall Sugars From Oak Barrels Into Bourbon Whiskey During Aging

Oak barrels have been used by humans for thousands of years to store and transport valuable materials. Early settlers of the United States in Kentucky began charring the interior of new white oak barrels prior to aging distillate to create the distinctively flavored spirit we know as bourbon whiskey. Despite the unique flavor and cultural significance of America\u27s Spirit , little is known about the wood-distillate interaction that shapes bourbon whiskey. Here, we employed an inverse method to measure the loss of specific wood polysaccharides in the oak cask during aging for up to ten years. We found that the structural cell wall wood biopolymer, cellulose, was partially decrystallized by the charring process. This pyrolytic fracturing and subsequent exposure to the distillate was accompanied by a steady loss of sugars from the cellulose and hemicellulose fractions of the oak cask. Distinct layers of structural degradation and product release from within the barrel stave are formed over time as the distillate expands into and contracts from the barrel staves. This complex, wood-sugar release process is likely associated with the time-dependent generation of the unique palate of bourbon whiskey

A Minimalist Approach to the Design of Complexity-Enriched Bioactive Small Molecules: Discovery of Phenanthrenoid Mimics as Antiproliferative Agents

Over the last decades, much effort has been devoted to the design of the “ideal” library for screening, the most promising strategies being those which draw inspiration from biogenic compounds, as the aim is to add biological relevance to such libraries. On the other hand, there is a growing understanding of the role that molecular complexity plays in the discovery of new bioactive small molecules. Nevertheless, the introduction of molecular complexity must be balanced with synthetic accessibility. In this work, we show that both concepts can be efficiently merged—in a minimalist way—by using very simple guidelines during the design process along with the application of multicomponent reactions as key steps in the synthetic process. Natural phenanthrenoids, a class of plant aromatic metabolites, served as inspiration for the synthesis of a library in which complexity-enhancing features were introduced in few steps using multicomponent reactions. These resulting chemical entities were not only more complex than the parent natural products, but also interrogated an alternative region of the chemical space, which led to an outstanding hit rate in an antiproliferative assay: four out of twenty-six compounds showed in vitro activity, one of them being more potent than the clinically useful drug 5-fluorouracil.Fil: Alonso, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Quezada, Maria Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Gola, Gabriel Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Richmond, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Cabrera, Gabriela Myriam. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Barquero, Andrea Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Ramirez, Javier Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentin

A crossover intervention trial evaluating the efficacy of a chlorhexidine-impregnated sponge in reducing catheter-related bloodstream infections among patients undergoing hemodialysis

BACKGROUND: Catheter-related bloodstream infections (BSI) account for the majority of hemodialysis-related infections. There are no published data on the efficacy of the chlorhexidine-impregnated foam dressing at reducing catheter-related BSI in hemodialysis patients. DESIGN: Prospective non-blinded cross-over intervention trial to determine the efficacy of a chlorhexidine-impregnated foam dressing (Biopatch®) to reduce catheter-related BSI in hemodialysis patients. SETTING: Two outpatient dialysis centers PATIENTS: A total of 121 patients who were dialyzed through tunneled central venous catheters received the intervention during the trial. METHODS: The primary outcome of interest was the incidence of catheter-related bloodstream infections. A nested cohort study of all patients who received the Biopatch® Antimicrobial Dressing was also conducted. Backward stepwise logistic regression analysis was used to determine independent risk factors for development of BSI. RESULTS: 37 bloodstream infections occurred in the intervention group for a rate of 6.3 BSIs/1000 dialysis sessions and 30 bloodstream infections in the control group for a rate of 5.2 BSIs/1000 dialysis sessions and [RR 1.22, CI (0.76, 1.97); P=0.46]. The Biopatch® Antimicrobial Dressing was well-tolerated with only two patients (<2%) experiencing dermatitis that led to its discontinuation. The only independent risk factor for development of BSI was dialysis treatment at one dialysis center [aOR 4.4 (1.77, 13.65); P=0.002]. Age ≥ 60 years [aOR 0.28 (0.09, 0.82); P=0.02] was associated with lower risk for BSI. CONCLUSION: The use of a chlorhexidine-impregnated foam dressing (Biopatch®) did not decrease catheter-related BSIs among hemodialysis patients with tunneled central venous catheters