Examinando por Autor "Carrasco, Héctor"
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Ítem Antifungal activity of eugenol analogues. Influence of different substituents and studies on mechanism of action(MDPI, 2012-01) Carrasco, Héctor; Raimondi, Marcela; Svetaz, Laura; Di Liberto, Melina; Rodriguez, María V.; Espinoza, Luis; Madrid, Alejandro; Zacchino, SusanaTwenty one phenylpropanoids (including eugenol and safrole) and synthetic analogues, thirteen of them new compounds, were evaluated for antifungal properties, first with non-targeted assays against a panel of human opportunistic pathogenic fungi. Some structure-activity relationships could be observed, mainly related to the influence of an allyl substituent at C-4, an OH group at C-1 and an OCH 3 at C-2 or the presence of one or two NO2 groups in different positions of the benzene ring. All active compounds were tested in a second panel of clinical isolates of C. albicans and non-albicans Candida spp., Cryptococcus neoformans and dermatophytes. The eugenol derivative 4-allyl-2-methoxy- 5-nitrophenol (2) was the most active structure against all strains tested, and therefore it was submitted to targeted assays. These studies showed that the antifungal activity of 2 was not reversed in the presence of an osmotic support such as sorbitol, suggesting that it does not act by inhibiting the fungal cell wall synthesis or assembly. On the other hand, the Ergosterol Assay showed that 2 did not bind to the main sterol of the fungal membrane up to 250 μg mL -1. In contrast, a 22% of fungal membrane damage was observed at concentrations = 1 × MIC and 71% at 4× MIC, when 2 was tested in the Cellular Leakage assay. The comparison of log P and MICs for all compounds revealed that the antifungal activity of the eugenol analogues would not to be related to lipophilicity. © 2012 by the authors.Ítem Antifungal activity of eugenol derivatives against Botrytis cinerea(MDPI, 2019-03) Olea, Andrés F.; Bravo, Angelica; Martínez, Rolando; Thomas, Mario; Sedan, Claudia; Espinoza, Luis; Zambrano, Elisabeth; Carvajal, Denisse; Silva-Moreno, Evelyn; Carrasco, HéctorBotrytis cinerea is a worldwide spread fungus that causes the grey mold disease, which is considered the most important factor in postharvest losses in fresh fruit crops. Consequently, the control of gray mold is a matter of current and relevant interest for agricultural industries. In this work, a series of phenylpropanoids derived from eugenol were synthesized and characterized. Their effects on the mycelial growth of a virulent and multi-resistant isolate of B. cinerea (PN2) have been evaluated and IC50 values for the most active compounds range between 31–95 ppm. The antifungal activity exhibited by these compounds is strongly related to their chemical structure, i.e., increasing activity has been obtained by isomerization of the double bond or introduction of a nitro group on the aromatic ring. Based on the relationship between the fungicide activities and chemical structure, a mechanism of action is proposed. Finally, the activity of these compounds is higher than that reported for the commercial fungicide BC-1000 that is currently employed to combat this disease. Thus, our results suggest that these compounds are potential candidates to be used in the design of new and effective control with inspired natural compounds of this pathogen. © 2019 by the authors.Ítem Antioxidant capacity of eugenol derivatives(Sociedade Brasileira de Química, 2009) Hidalgo, María E.; De la Rosa, Carlos; Carrasco, Héctor; Cardona, Wilson; Gallardo, Claudio; Espinoza, LuisToxicity and antioxidant capacity of eugenol derivatives (E2 = 2-Methoxy-4-[1-propenylphenyl]acetate, E3 = 4-Allyl-2-methoxyphenylacetate, E4 = 4-Allyl-2-methoxy-4-nitrophenol, E5 = 5-Allyl-3-nitrobenzene-1,2-diol, E6 = 4-Allyl-2-methoxy-5-nitrophenyl acetate) were evaluated in order to determine the influence of the sustituents. E2-E6 were synthesized from eugenol (E1). E1 was extracted from cloves oil, and E2-E6 were obtained through acetylation and nitration reactions. Antioxidant capacity evaluated by DPPH (1, 1-Diphenyl-2-picrylhydrazil) and ORAC fluorescein demonstrated that E1 and E5 have a higher capacity and the minor toxicity evaluated by red blood cells haemolysis and the Artemia saline test. In accordance with our results, the compound's (E1-E5) use in the pharmaceutical, cosmetic and or food industries could be suggested.Ítem Caracterización de la actividad antifúngica de poligodial sobre el hongo fitopatógeno Botrytis Cinerea(Universidad Andrés Bello, 2018) Robles Kelly, Christian Gonzalo; Silva Moreno, Evelyn; Carrasco, Héctor; Facultad de Ciencias Biológicas; Escuela de Ingeniería en BiotecnologíaEl hongo Botrytis cinerea, causante de la pudrición gris (PG), es un patógeno capaz de afectar a una gran variedad de cultivos agrícolas. En Chile, este hongo afecta a diversas especies frutícolas entre las que se encuentra la uva de mesa, uno de los principales productos de exportación de nuestro país. Tradicionalmente, el control de la PG se realiza mediante el uso de fungicidas químicos como benzimidazoles, fenilcarbamatos, dicarboximidas y anilinopirimidinas. Sin embargo, el uso intensivo y prolongado de estos fungicidas ha llevado a la aparición de cepas del hongo que muestran diversos niveles de resistencia. En Chile la aparición de aislados de B. cinerea resistentes a estos fungicidas ha ido aumentando progresivamente, alcanzando un 60% el año 2011. Estos antecedentes han impulsado la búsqueda de nuevos agentes fungicidas y/o formulaciones, eficientes y amigables con el medio ambiente, para el control de B. cinerea. Es por ello por lo que, como alternativa se plantea, la producción de una nueva generación de antifúngicos en base a compuestos naturales, extraídos de plantas. El propósito de esta investigación fue evaluar la actividad antifúngica del compuesto natural, poligodial, extraído desde el árbol del canelo, sobre el hongo fitopátogeno B.cinerea. Para ello, se realizaron estudios sobre el efecto de inhibición del crecimiento micelial y germinación de las conidias. Además de estudiar el mecanismo de acción por el cual actúa poligodial, a través de ensayos de estabilización de membrana, acumulación de especies reactivas de oxígeno y análisis de genes relacionados con daño celular. Se logró establecer que poligodial presenta una actividad biológica sobre la germinación de las conidias, provocando una ralentización del crecimiento micelial y el mecanismo de acción se asocia a la desestabilización de membrana.Ítem Efecto de Poligodial, Drimenol, Confertifolina y diferentes extractos obtenidos desde Drymis Winteri sobre los procesos de proliferación y muerte celular en diferentes líneas celulares de cáncer(Universidad Andrés Bello (Chile), 2013) Tomasoni Orozco, Giácomo Luigi.; Villena, Joan; Martínez, Rolando; Carrasco, Héctor; Facultad de Ciencias Biológicas. Escuela de Ingeniería en Biotecnología.El cáncer es la segunda causa de muerte por enfermedad a nivel mundial de acuerdo a datos publicados por la Organización Mundial de la Salud. Dado el impacto a nivel global de esta patología y que el abordaje farmacológico "tradicional" ha tenido un éxito limitado, se torna cada vez más necesario seguir investigando nuevos posibles fármacos, enfocándose no solo en el desarrollo sintético de estos, sino también explorando el sin número de moléculas de origen natural existentes, haciendo especial énfasis en las provenientes de plantas. Es así al explorar como surge una familia de moléculas que desde un punto de vista biológico es muy importante, los Sesquiterpenos. Éstas son moléculas con amplia actividad biológica y que están presentes en gran variedad de plantas, entre ellas una planta autóctona chilena, el "Canelo" (Drymis winteri). Esta planta presenta una gran variedad de sesquiterpenos, de los cuales en este estudio se utilizaron Confertifolina, Drimenol y Poligodial, además de diferentes extractos de la planta obtenidos con acetato de etilo, etanol, hexano, metanol y el aceite esencial. En este estudio se determinó la citotoxicidad tanto de estos compuestos como la de los extractos obtenidos desde Canelo mediante ensayos de viabilidad celular con Sulforodamina B, donde se vio que Poligodial y el extracto metanólico poseen los mayores efectos citotóxicos sobre las células (disminuyen la viabilidad celular). Posteriormente las células tratadas se tiñeron con Hoechst 33342 para observarse que todos los compuestos y extractos inducen condensación y/o fragmentación de la cromatina en las líneas cancerígenas, característica asociada a procesos apoptóticos. A continuación , se realizó un marcaje de las células con Rodamina 123 y analizándose éstas por citometría de flujo para determinar cambios en la permeabilidad de la membrana mitocondrial, ya que la mitocondria es un orgánulo clave en la determinación de la muerte celular programada. Los resultados indicaron que Poligodial es el único compuesto que afecta la permeabilidad de la membrana mitocondrial y que todos los extractos, salvo el aceite esencial, inducen un efecto similar sobre la permeabilidad de la membrana mitocondrial. En cambio, mediante ensayos de actividad de Caspasa 3 , pudimos determinar que solo Poligodial y Confertifolina aumentan la actividad de Caspasa 3 en las líneas tratadas . Finalmente, se determinó que la citotoxicidad inducida por los compuestos y por los extractos estudiados implican de forma directa o indirecta a las proteasas Caspasa 3/7, viéndose estos resultados gracias al análisis de la recuperación de viabilidad celular tras pretratar células con un inhibidor de Caspasa 3/7 y posteriormente tratar con los compuestos y extractos y realizar el ensayo de viabilidad celular con Sulforodamina B en éstas.Ítem Synthesis and DPPH radical scavenging activity of prenylated phenol derivatives(MDPI, 2012-01) Osorio, Mauricio; Aravena, Jacqueline; Vergara, Alejandra; Taborga, Lautaro; Baeza, Evelyn; Catalán, Karen; González, Cesar; Carvajal, Marcela; Carrasco, Héctor; Espinoza, LuisThe synthesis of twenty six prenylated phenols derivatives is reported. These compounds were obtained under mild conditions via Electrophilic Aromatic Substitution (EAS) coupling reactions between phenol derivatives containing electron-donor subtituents and 3-methyl-2-buten-1-ol using BF 3·OEt 2. Dialkylations were also produced with this method. The formation of a chroman ring by intramolecular cyclization between a sp 2 carbon from the prenyl group with the hydroxyl substituent in the ortho position occurred with some phenols. All the synthesized compounds were evaluated as antioxidants according to a DPPH radical scavenging activity assay. IC 50 values of five synthesized compounds indicated they were as good antioxidants as Trolox™. © 2012 by the authors.Ítem Synthesis and in vitro growth inhibition of 2-allylphenol derivatives against Phythopthora cinnamomi rands(MDPI AG, 2019-11) Olea, Andrés F.; Espinoza, Luis; Sedan, Claudia; Thomas, Mario; Martínez, Rolando; Mellado, Marco; Carrasco, Héctor; Díaz, KatyPhytophthora cinnamomi is a phytopathogen that causes extensive damage in different crops, and therefore, produces important economic losses all around the world. Chemical fungicides are a key factor for the control of this disease. However, ecological and environmental considerations, as well as the appearance of strains that are resistant to commercial fungicides, have prompted the quest for new antifungal agents which are of low ecological impact. In this work, a series of new 2-allylphenol derivatives was synthesized, and their structures were confirmed by FT-IR, NMR, and MS. Some of the synthesized compounds, more specifically nitro derivatives, exhibit strong growth inhibition of P. cinnamomi with EC50 as low as 10.0 μg/mL. This level of activity is similar to that exhibited by METALAXYL MZ 58 WP, a commonly-used commercial fungicide; therefore, these compounds might be of agricultural interest due to their potential use as fungicides against P. cinnamomi. The results indicate that this activity depends on the chemical structures of the 2-allylphenol derivatives, and that it is strongly enhanced in molecules where nitro and hydroxyl groups adopt a -para configuration. These effects are discussed in terms of the electronic distribution of the aromatic ring induced by substituent groups. © 2019 by the authors.Ítem Synthesis and NMR structure determination of new linear geranylphenols by direct geranylation of activated phenols.(Sociedad Chilena de Química, 2013) Taborga, Lautaro; Vergara, Alejandra; Fernández A., María José; Osorio, Mauricio; Carvajal, Marcela; Madrid, Alejandro; Marilaf, Francisco; Carrasco, Héctor; Espinoza Catalán, LuisThe known geranylhydroquinone 2, geranylorcinol 4 and the derivative (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-methylbenzene-1,3-diol 5, were prepared by Electrophilic Aromatic Substitution (EAS) reactions between the corresponding phenol derivatives containing electron-donor subtituents and geraniol using BF3XOEt2 as a catalyst. In addition, spectroscopic NMR information for 4 and 5 is complemented. Furthermore, the new (E)-2-(3,7-dimethylocta-2,6-dienyl) benzene-1,3,5-triol (geranylphloroglucinol) 13, (E)-2-(3,7-dimethylocta-2,6-dienyl)-1,3,5-trimethoxybenzene 14, (E)-2-(3,7-dimethylocta-2,6-dienyl)-6-methoxyphenol 15, (E)-3-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 16, (E)-5-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 17, (E)-4-(3,7-dimethylocta-2,6-dienyl)benzene-1,3-diol 18, (E)-3-(3,7-dimethylocta-2,6-dienyl)benzene-1,2-diol 19, (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-isopropyl-2-methylphenol 20, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-3-methylphenol 21, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-5-methylphenol 22, and(E)-2-tert-butyl-4-(3,7-dimethylocta-2,6-dienyl)-5-methylphenol 23 were also prepared with this synthesis strategy. All the synthesized compounds were fully characterized and their structures were established by IR, MS and mainly NMR spectroscopic dates.