RESUMEN Objetivos: este estudio investigó la bioactividad del extracto de hoja en bruto (EHB) y las fracciones hexano (HX) y acetato de etilo (AcOEt) de Talinum paniculatum solo y en asociación con fluconazol (FLC) contra cepas de referencia y aislados clínicos de Candida albicans resistente a FLC. Además, evaluó la capacidad antioxidante, la composición química de esta planta y los mecanismos subyacentes del efecto fungicida. Métodos: la actividad antifúngica se evaluó mediante microdilución en caldo para establecer las concentraciones inhibitorias mínimas (CIM) y microbicidas mínimas (CMM). Durante el tratamiento con FLC y productos vegetales se detectó la generación de especies reactivas de oxígeno (ERO) (radicales hidroxilo [HO●]) en células de C. albicans utilizando las sondas fluorescentes permeables a la membrana APF y HPF. El perfil de cromatografía líquida de alta resolución (CLAR), el análisis cuantitativo de compuestos antioxidantes y el ensayo DPPH fueron evaluados. Resultados: el EHB y las fracciones presentaron una excelente actividad antifúngica y selectividad contra las células de C. albicans, pero no tuvieron efectos sinérgicos con FLC. Los valores de CIM para EHB y sus fracciones contra la cepa referencia de C. albicans fueron del orden de: HX (31,25 μg ml-1) < AcOEt (62,5 μg ml-1) < EHB (500 μg ml-1), y contra C. albicans resistente a FLC: HX (125 μg ml-1)= AcOEt < EHB (500 µg ml-1). EHB y sus fracciones fueron más potentes antifúngicos que FLC contra los aislados clínicos. Además, estos productos vegetales tienen efectos fungicidas contra C. albicans resistentes a FLC, esto conirmó el potencial antifúngico. Por el contrario, durante la asociación se demostró que los productos vegetales causan un aumento en la CIM de FLC de 2 a 16 veces. La exposición a FLC aumentó los niveles de ERO (HO●) en las células de C. albicans. Los aumentos en las CIM de FLC se debieron a la acción de los antioxidantes presentes en EHB y sus fracciones para prevenir la inhibición del crecimiento mediada por ERO inducida por FLC en C. albicans. Conclusión: T. paniculatum puede ser una fuente de compuestos bioactivos con potencial antifúngico. Sin embargo, debido al uso común de su hoja comestible, se recomienda usarla con precaución durante la terapia con FLC (ya que puede disminuir la susceptibilidad a FLC).

SUMMARY Aims: This study investigated the bioactivity of the crude leaf extract (CLE) and fractions hexane (HX) and ethyl acetate (EtOAc) from Talinum paniculatum alone and in association with fluconazole (FLC) against reference strain and clinical isolates of FLC-resistant Candida albicans. Furthermore, the antioxidant capability, chemical composition of this plant, and the effect's underlying mechanisms were evaluated. Methods: The antifungal activity was evaluated using checkerboard assay to establish the minimum inhibitory (MIC) and minimum microbicidal concen trations (MMC). During FLC and plant products challenges, the reactive oxygen species (ROS) generation (hydroxyl radicals [HO●]) were detected in C. albicans cells using the membrane-permeable fluorescent probes APF and HPF. High-performance liquid chromatography (HPLC) profile, quantitative analysis of antioxidant compounds, and free radical scavenging activity (DPPH assay) tests were performed. Results: The CLE and fractions presented outstanding antifungal activity and selectivity against C. albicans cells but had no synergistic effect’s with FLC. The MIC values for CLE and its fractions against C. albicans reference strain were in the order of HX (31.25 µg ml-1) < EtOAc (62.5 μg ml-1) < CLE (500 μg ml-1), and against FLC-resistant C. albicans HX (125 μg ml-1) = EtOAc < CLE (500 μg ml-1). CLE and its fractions had more potent antifungal activities than FLC against the clinical isolates. Moreover, fungicidal effect’s for these plant products were demonstrated against FLC-resistant C. albicans, which further conirmed an antifungal potential. Conversely, during association, plant products were shown to cause an increase in FLC MIC anywhere from 2- to 16-fold. FLC exposure led to an increase in the steady-state levels of ROS (HO●) in C. albicans cells. Next, we found that the increases in FLC MICs were owing to action of antioxidants containing-CLE and its fractions in preventing FLC-induced ROS-mediated growth inhibition of C. albicans. Conclusion: T. paniculatum can be a source of bioactive compounds with antifungal potential. However, because of the common use of its edible leaf, caution is advised during therapy with FLC (since it can decrease FLC susceptibility).

As variações de temperatura que ocorrem durante a cadeia refrigerada da produção leiteira pode interferir na qualidade de alimentos bioativos, como leites fermentados. Bactérias probióticas são usualmente adicionadas a alimentos, visando a oferecer ao consumidor efeitos benéficos. O objetivo deste trabalho foi avaliar a viabilidade de culturas probióticas de bifidobactérias e de cultura starter de Streptococcus thermophilus em leites fermentados, armazenados nas temperaturas de 4 e 10ºC por um período de 28 dias. Culturas comerciais de Bifidobacterium spp. foram adicionadas ao leite fermentado produzido com Streptococcus thermophillus e estocados por 28 dias a 4 e 10ºC. Nesse período, as culturas deBifidobacterium spp. e Streptococcus thermophillus foram monitoradas, com o objetivo de verificar seus comportamentos nas temperaturas de estocagem testadas. As contagens de ambos os micro-organismos não apresentaram variação significativa ao longo do período de estocagem a 4 e a 10ºC (p < 0,05), indicando que as duas temperaturas testadas podem oferecer condições adequadas de conservação desse produto. Os resultados obtidos indicaram que as condições de conservação de alimentos usualmente adotadas para produtos lácteos em estabelecimentos comerciais são adequadas para manter as contagens de bifidobactérias e Streptococcus thermophillus em leites fermentados.

The variations of temperature during the cold chain can impair the quality of live foods, such as fermented milks. Probiotic bacteria are commonly added to food to provide the consumer with beneficial effects. Nevertheless, the concentration of probiotic in the end products should be elevated to ensure functionality. The aim of this study was to evaluate the viability of probiotic strains of bifidobacteria and starter strain of Streptococcus thermophilus in fermented milks at storage temperatures of 4 and 10ºC, for a period of 28 days. Commercial cultures ofBifidobacterium spp. were added to milk fermented byStreptococcus thermophillusand stored for 28 days at 4 and 10ºC. During this period, bifidobacteria and S. thermophilluscultures were monitored to check their behavior in the evaluated storage conditions. Viable bifidobacteria and S. thermophillus counts showed no significant variation during storage at 4 and 10ºC (p < 0.05), indicating that both of these conditions are adequate for maintaining their initial concentrations. The results indicate that the storage conditions usually adopted in sale establishments of dairy products are suitable to maintain bifidobacteria and S. thermophillus cultures in fermented milk.