Leticia Barrientos

The antifungal effect of six commercial extracts of Chilean propolis on Candida spp

Propolis has been used in traditional medicine for many centuries because of its beneficial health properties, including its antimicrobial capacity. Prosthesis stomatitis affects a significant percentage of users of removable dentures; Candida albicans is the most common fungal species associated with the development of this pathology. Thus, the objectives of this study were: a. To evaluate the antifungal activity of six commercial propolis extracts against Candida spp. that was isolated from the oral cavity of removable dentures users, and b. To determine chemical characteristics of the propolis extracts evaluated. Among the results, we note that these concentrations of polyphenols varied between 9 ± 0.3 and 85 ± 2.1 mg mL-1. Chromatographic analysis was able to detect 35 compounds, among which were caffeic acid, myricetin, quercetin, kaempferol, apigenin, pinocembrin, galangin, and caffeic acid phenyl ester (CAPE). All strains tested were inhibited by the liquid extracts of propolis. The MID ranged between 1:40 and 1:1280, and the MIC for C. albicans ranged from 197 µg mL-1 to 441 µg mL-1. From the results obtained in this investigation, we can conclude that all propolis extracts evaluated are capable of inhibiting the development of Candida spp. However, they show significant differences in the concentration of polyphenols present and in antifungal activity. El propoleo ha sido utilizado por la medicina tradicional desde hace muchos siglos debido a sus propiedades beneficas para la salud, entre las que destaca su capacidad antimicrobiana. La estomatitis subprotesica, afecta a un porcentaje importante de usuarios de protesis dental removible, siendo Candida albicans la especie fungica mas comun asociada al desarrollo de esta patologia. Asi, los objetivos de este estudio fueron: a) evaluar la actividad antifungica de seis extractos de propoleos comerciales sobre cepas de Candida spp. aisladas de la cavidad oral de usuarios de protesis dental removible, y b) determinar algunas caracteristicas quimicas de los extractos de propoleos utilizados. Entre los resultados obtenidos, podemos senalar que estos mostraron concentraciones de polifenoles que variaron entre 9 ± 0,3 y 85 ± 2,1 mg/mL. El analisis cromatografico permitio detectar 35 compuestos, entre los cuales se logro identificar la presencia de acido cafeico, miricetina, quercetina, kaempferol, apigenina, pinocembrina, galangina y acido cafeico fenil ester (CAPE). Todas las cepas de Candida spp. evaluadas fueron inhibidas por los seis extractos liquidos de propoleos, observandose que la DIM vario entre 1/40 y 1/1280, y la CIM para C. albicans vario entre 197 µg/mL y 441 µg/mL. A partir de los resultados obtenidos en esta investigacion podemos concluir que todos los propoleos evaluados son capaces de inhibir el desarrollo de Candida spp. , sin embargo, estos muestran importantes diferencias en la concentracion de los polifenoles presentes y en la actividad antifungica.

Chemical and botanical characterization of Chilean propolis and biological activity on cariogenic bacteria Streptococcus mutans and Streptococcus sobrinus

Propolis is a non-toxic natural substance with multiple pharmacological properties including anti-cancer, antioxidant, fungicidal, antibacterial, antiviral, and anti-inflammatory among others. The aim of this study was to determine the chemical and botanical characterization of Chilean propolis samples and to evaluate their biological activity against the cariogenic bacteria Streptococcus mutans and Streptococcus sobrinus. Twenty propolis samples were obtained from beekeeping producers from the central and southern regions of Chile. The botanical profile was determined by palynological analysis. Total phenolic contents were determined using colorimetric assays. Reverse phase HPLC and HPLC-MS were used to determine the chemical composition. The minimum inhibitory concentration (MIC) was determined on S. mutans and S. sobrinus. All propolis samples were dominated by structures from native plant species. The characterization by HPLC/MS, evidenced the presence of quercetin, myricetin, kaempferol, rutine, pinocembrin, coumaric acid, caffeic acid and caffeic acid phenethyl ester, that have already been described in these propolis with conventional HPLC. Although all propolis samples inhibited the mutans streptococci growth, it was observed a wide spectrum of action (MIC 0.90 to 8.22 μg mL−1). Given that results it becomes increasingly evident the need of standardization procedures, where we combine both the determination of botanical and the chemical characterization of the extracts. Research conducted to date, describes a promising effectiveness of propolis in the prevention of caries and other diseases of the oral cavity, making it necessary to develop studies to identify and understand the therapeutic targets or mechanisms of molecular action of the various compounds present on them.

Effect of Chilean propolis on cariogenic bacteria Lactobacillus fermentum

La caries dental es una de las enfermedades infecciosas mas prevalentes en el mundo. Entre las bacterias involucradas en esta patologia se encuentran Streptococcus mutans, Streptococcus sobrinus, Actinomyces spp. y Lactobacillus spp. La industria farmaceutica ha volcado sus esfuerzos al descubrimiento de nuevos productos antibacterianos ante el aumento de resistencia a los ya conocidos. El propoleos se ha utilizado como tal, desde tiempos antiguos, por lo que se ha investigado su efecto contra variados microorganismos. En este estudio se evaluo el efecto antimicrobiano de seis extractos etanolicos comerciales de propoleos, sobre la bacteria Lactobacillus fermentum. Esta fue aislada luego de su identificacion mediante PCR con el uso de primers especie especificos, posterior al cultivo microbiologico de muestras de caries de pacientes con indicacion de extraccion de pieza dental, y se detecto en 9 de 40 pacientes, correspondiendo a un 22%. El estudio de susceptibilidad se realizo mediante dilucion en microplacas y se comprobo la actividad antimicrobiana en cuatro de los seis extractos etanolicos de propoleos utilizados, difiriendo en la concentracion efectiva contra el microorganismo, lo que puede ser atribuido a factores como el origen botanico, el lugar geografico y la estacion de recoleccion. Los propoleos mostraron concentraciones de polifenoles que variaron entre 9 ± 0,3 y 85 ± 2,1 mg/mL. El analisis cromatografico permitio detectar la presencia de acido cafeico, miricetina, quercetina, kaempferol, apigenina, pinocembrina, galangina y acido cafeico fenil ester (CAPE). Nuestro estudio demuestra la accion antimicrobiana del propoleos sobre L. fermentum, patogeno relacionado al desarrollo de caries.

Antibiofilm Activity of Chilean Propolis on Streptococcus mutans Is Influenced by the Year of Collection

The chemical composition of propolis varies according to factors that could have an influence on its biological properties. Polyphenols from propolis have demonstrated an inhibitory effect on Streptococcus mutans growth. However, it is not known if different years of propolis collection may affect its activity. We aimed to elucidate if the year of collection of propolis influences its activity on Streptococcus mutans. Polyphenol-rich extracts were prepared from propolis collected in three different years, characterized by LC-MS and quantified the content of total polyphenols and flavonoids groups. Finally, was evaluated the antibacterial effect on Streptococcus mutans and the biofilm formation. Qualitative differences were observed in total polyphenols, flavones, and flavonols and the chemical composition between the extracts, affecting the strength of inhibition of biofilm formation but not the antimicrobial assays. In conclusion, chemical composition of propolis depends on the year of collection and influences the strength of the inhibition of biofilm formation.

Soils suppressive against Gaeumannomyces graminis var. tritici identified under wheat crop monoculture in southern Chile

Incrementar el conocimiento del fenomeno biologico de los suelos supresivos es un aspecto critico para el manejo y control biologico de patogenos vegetales asociados al suelo. Los Andisoles del sur de Chile son suelos altamente predisponentes para la pudricion radical del trigo, causada por el hongo Gaeumannomyces graminis var. tritici. Sin embargo, no existen antecedentes de investigaciones sobre la presencia de suelos supresivos a esta enfermedad en esta importante zona productora de trigo. La primera parte de este estudio tuvo como proposito identificar suelos supresivos a la pudricion radical del trigo para luego, caracterizar su microflora en la busqueda de potenciales agentes de control biologico del agente causal. En base a la transferencia de la supresividad al mismo suelo evaluado, previamente esterilizado, veinte suelos colectados en diferentes areas productoras de trigo del sur de Chile, fueron clasificados como supresivos o conductivos a la pudricion radical, bajo condiciones de inoculacion artificial en invernadero. Se encontro propiedades altamente supresivas hacia la enfermedad en cinco de estos suelos, los cuales poseian un largo historial de monocultivo de trigo. Ambos tipos de suelos, supresivos y conductivos, comparten caracteristicas fisico-quimicas similares. Este es el primer reporte sobre suelos supresivos a la pudricion radical del trigo en Chile.

Acción Antimicrobiana in vitro de la Miel de Abejas sobre los Microorganismos Cariogénicos Estreptococos del Grupo mutans

En el presente estudio fue evaluada la actividad antimicrobiana in vitro de cuatro muestras de mieles producidas en nuestro pais, sobre los recuentos de estreptococos del grupo mutans, en escolares con alto riesgo de caries dental. Se obtuvieron muestras de saliva de 20 escolares, con edades entre 12 y 14 anos, pertenecientes a la ciudad de Temuco, Region de La Araucania (Chile). El recuento de estreptococos del grupo mutans en saliva fue estimado por el metodo microbiologico semi-cuantitativo Linoscreen®. La evaluacion de la accion antibacteriana de la miel se realizo en 9 escolares que presentaron los recuentos mas elevados de estreptococos del grupo mutans, utilizando concentraciones de miel entre 5% y 35%. Los datos mostraron que el 100% de los ninos analizados poseian colonias de estreptococos del grupo mutans en su saliva. Ademas, se verifico que el 45% (9/20) de los escolares se encontraba en la categoria de alta actividad cariogenica. Con este estudio, tambien se comprobo que la miel de abejas posee actividad antimicrobiana sobre las bacterias estreptococos del grupo mutans y que no existian diferencias significativas entre las 4 mieles utilizadas, con relacion a su capacidad antibacteriana (p>0.05). Por otra parte, este estudio tambien permitio demostrar que a mayor concentracion de miel utilizada mayor era la reduccion de las bacterias cariogenicas. En conclusion, en el presente estudio se demostro la accion antimicrobiana in vitro de la miel sobre los recuentos de bacterias cariogenicas estreptococos del grupo mutans. Sin embargo, seran necesarios futuros estudios para identificar y evaluar los componentes de la miel de abejas, responsables de esta propiedad.

Streptomyces luridus So3.2 from Antarctic soil as a novel producer of compounds with bioemulsification potential

The present study aimed to identify novel microbial producers of bioemulsificant compounds from Antarctic soils. Fifty-nine microbial strains were isolated from five different locations at South Shetland Islands, Antarctica, and screened for biosurfactant production by β-hemolytic activity. Strain So 3.2 was determined as bioemulsifier-producer and identified by phenotypic and molecular characterization as Streptomyces luridus. Emulsification activity, oil displacement method and drop-collapsing test were performed to evaluate the biosurfactant activity with different oils and hydrocarbons using two different culture media (Luria Bertani and Bushnell Haas in the presence of different carbon sources: glucose, glycerol, olive oil and n-Hexadecane). Cell free supernatant of Bushnell Haas culture supplemented with n-Hexadecane showed the best results for all tests. Emulsification of hydrocarbons exceeded 60%, reaching up to 90% on oil with high API grade, while displacement tests ranged from 8 cm to 4 cm in diameter according the culture media and tested oils. Our results revealed that Streptomyces luridus So3.2 is able to produce bioemulsifiers capable of emulsifying hydrocarbons and oils, which could be used in different biotechnological applications, particularly for bioremediation of environments contaminated by oil leaks.

Polyphenol-Rich Extract from Propolis Reduces the Expression and Activity of Streptococcus mutans Glucosyltransferases at Subinhibitory Concentrations

Tooth decay is an infectious disease, whose main causative agent identified is Streptococcus mutans (S. mutans). Diverse treatments have been used to eradicate this microorganism, including propolis. To date, it has been shown that polyphenols from Chilean propolis inhibit S. mutans growth and biofilm formation. However, the molecular mechanisms underlying this process are unclear. In the present study, we assessed the effect of Chilean propolis on the expression and activity of the glycosyltransferases enzymes and their related genes. Polyphenol-rich extract from propolis inhibited gene expression of glycosyltransferases (GtfB, GtfC, and GtfD) and their related regulatory genes, for example, VicK, VicR, and CcpA. Moreover, the treatment inhibited glucosyltransferases activity measured by the formation of sucrose-derived glucans. Additionally, an inhibitory effect was observed in the expression of SpaP involved in sucrose-independent virulence of S. mutans. In summary, our results suggest that Chilean propolis has a dose-dependent effect on the inhibition of genes involved in S. mutans virulence and adherence through the inhibition of glucosyltransferases, showing an anticariogenic potential of polyphenols from propolis beyond S. mutans growth inhibition.