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.

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SUMMARYCatastrophic disturbances of forest ecosystems are natural and anthropogenic phenomena that promote the natural dynamics of biocenosis and biogeochemical processes, and are the main causes of landscape fragmentation. The aim of this study was to evaluate the effect of orientation and toposequential positions on some biological activities in a relict forest community of LapagerioAextoxiconetum during two seasons. Soil samples were collected from an Andisol (0-15 cm), for each toposequential position (high, medium and low slope) of a forest with orientation northeast and southwest in summer and winter. The parameters evaluated were: fluorescein diacetate hydrolysis, carbon and nitrogen biomass and activity of six enzymes related to microbiological activity: carboximethylcellulase, β-glucosidase, manganese peroxidase, urease, acid phosphatase and arylsulfatase. The results indicate that the high slope with northeast orientation showed most favourable conditions on biological activities. In turn, orientation had direct effects on the evaluated biological activities, mostly significant, due to variation in soil moisture, temperature, pH, organic matter content and nutrient availability. Urease was the only enzyme with higher activity levels in summer, because of increase in soil temperature. Biological activities were affected by seasonality, being significantly higher in winter; the differences observed for different biological parameters are attributed to microclimates that were generated under the tree canopy and mulch.Key words: temperate forests, toposequence, microbial biomass, soil enzyme activities. RESUMENLas alteraciones catastróficas en ecosistemas boscosos son fenómenos naturales o antropogénicos que promueven la dinámica natural de la biocenosis y los procesos biogeoquímicos, y constituyen la principal causa de fragmentación del paisaje. El objetivo de este estudio fue evaluar el efecto de la exposición y la toposecuencia sobre algunas actividades biológicas del suelo de un bosque relicto de la comunidad Lapagerio-Aextoxiconetum, en dos estaciones del año. Se recolectaron muestras de suelo (0-15 cm), con características de Andisol por cada uno de los niveles toposecuenciales (laderas alta, media y baja) con exposición noreste y suroeste, en verano e invierno. Los parámetros evaluados fueron: hidrólisis de la fluoresceína diacetato, carbono y nitrógeno en la biomasa microbiana y la actividad de seis enzimas relacionadas con la actividad microbiológica: carboximetilcelulasa, β-glucosidasa, manganeso peroxidasa, ureasa, fosfatasa ácida y arilsulfatasa. Los resultados obtenidos indican que la ladera alta con exposición noreste presentó condiciones más favorables para las actividades biológicas. La exposición tuvo efectos directos sobre las actividades biológicas, mayoritariamente significativos, debido a la variación del suelo en humedad, temperatura, pH, contenido de materia orgánica y disponibilidad de nutrientes. La ureasa fue la única enzima con mayor actividad en verano, debido al aumento de la t...

Persea lingue Ness is a tree species that lives mainly in temperate forests of south-central Chile. Its leaves are used in ethnomedicine, the fruit is a drupe similar to that of the avocado and has not been studied. The aim of this study was to determine the cytotoxicity in leukemia cell and antibacterial activity, along with some chemical content characteristics of P. lingue fruit and leaf extracts. The antibacterial activity was determined by the inhibition of bacterial growth in liquid medium assay against Gram-positive and Gram-negative bacteria. The leukemia cell lines Kasumi-1 and Jurkat were used to evaluate the cytotoxic activity by using propidium iodide and AlamarBlue assays. Total phenolic, flavonoid, condensed tannin, alkaloid and lipid contents were evaluated in the fruit and in the leaf extracts. The antioxidant activity of both extracts were also elavaluated. Leaf extract presented the highest content of total phenols, condensed tannins and flavonoids, and also the highest antioxidant activity. While the fruit extract has a higher amount of lipids and alkaloids and the high antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus megaterium and Micrococcus luteus. The leaf extract only showed activity against M. luteus. Concerning the cytotoxic activity, only the fruit extract showed cytotoxicity against the cell lines Jurkat and Kasumi-1. P. lingue fruit extract is a potential source of biologically active molecules for the development of new drugs to be used in some types of leukemia, as well as antibacterial agent.

Descripción estructural de la formación vegetal subtipoJubaea chilensis -Lithraea caustica, al interior del Parque Nacional La Campana