Percorrer por autor "Nunes, Susana"
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- Antibacterial activity of propolis extracts from the south of PortugalPublication . Oliveira, Ana; Ferreira, Ana Luisa; Nunes, Susana; Dandlen, Susana; Miguel, Maria; Faleiro, Maria LeonorTo examine the antibacterial activity of diverse extracts of propolis harvested at winter and spring from several locations of Algarve, Portugal, against Gram-negative and Gram-positive bacteria was the main goal of the present work. For such, the antibacterial activity was determined by agar diffusion. The results showed that all tested bacterial strains showed susceptibility to diluted propolis extracts and in a dose-dependent manner. Two propolis samples collected at springtime showed higher antibacterial activity, in comparison with samples harvested at wintertime. Ethanolic and methanolic extracts have a very similar activity (P<0.05). Helicobacter pylori strains J99 and 26695 were the most susceptible strains to the tested extracts (33.67 +/- 2.52 mm and 35.67 +/- 0.58mm, respectively). This study constitutes the first approach of the biological activities of Portuguese propolis from the Algarve region and evidences its potential use to combat bacterial infections, in particular against the gastric pathogen H. pylori.
- Climatology and nutrient fluxes in the Tagus estuary: A coupled model applicationPublication . de Pablo, Hilda; Sobrinho, João; Nunes, Susana; Correia, Alexandre; Neves, Ramiro; Gaspar, MiguelRivers are responsible for the main transport of nutrients from land to estuaries and coastal areas. Understanding the fate of these anthropogenic inputs and their impacts on estuaries and adjacent marine ecosystems is essential for the protection of coastal waters. Here, the 3D MOHID hydrodynamic model coupled with a biogeochemical model was used to determine seasonal nutrient fluxes between areas of the Tagus estuary. For this purpose, the estuary was divided into boxes, which allowed to evaluate nutrients (and phytoplankton) exchanges between areas, to identify source and sink zones, to estimate the amount of nutrients exported to the coastal zone adjacent to the estuary, and to understand the recycling capacity of this estuarine system. Globally, for all nutrients and seasons, the highest net fluxes were observed in the main and central body of the estuary. The differences observed in the flux budget for each box and for all nutrients are mostly related to variations in the seasonal abundance of phytoplankton, which is much higher in Spring/Summer than in the rest of the year due to the higher seawater temperature and irradiance. During these seasons the high temperatures also promoted the fast mineralization of organic matter along the water column and in the sediment. For all seasons, an export of nutrients and phytoplankton from upstream to downstream was observer at the surface, and from the most confined areas of the southern margin into the central body and main channel of the estuary, whilst the opposite was observed in the bottom layers. Nevertheless, surface fluxes were always higher than those recorded at depth, indicating that the estuary exported nutrients to the coast, all year round. For 2020 it was estimated that 52%, 88% and 65% of the ammonium, nitrate, and phosphate, respectively, that entered the estuary from both rivers and wastewater treatment plants were exported to the adjacent coast. The amount of nutrients exported to the coastal area is closely related to river discharge, being much higher in flood years than in dry years, particularly for nitrate.
- Phenols, flavonoids and antioxidant activity of aqueous and methanolic extracts of propolis (Apis mellifera L.) from Algarve, South PortugalPublication . Miguel, Maria; Nunes, Susana; Dandlen, Susana Anahi; Cavaco, Ana Maria; Antunes, Maria DulcePropolis is a resinous substance collected by honeybees to seal honeycomb, which has been used in folk medicine due to its antimicrobial and antioxidant properties. In the present study, water and methanol were used to extract phenols and flavonoids from propolis collected in thirteen different areas in the Algarve region during the winter and spring. The ABTS(center dot+), DPPH center dot, and O-2(center dot-) scavenging capacity, and metal chelating activity were also evaluated in the propolis samples. Methanol was more effective than water in extracting total phenols (2.93-8.76 mg/mL) (0.93-2.81 mg/mL). Flavones and flavonols were also better extracted with methanol (1.28-2.76 mg/mL) than with water (0.031-0.019 mg/mL). The free radical scavenging activity, ABTS (IC50 = 0.006-0.036 mg/mL), DPPH (IC50 = 0.007-0.069 mg/mL) and superoxide (IC50 = 0.001-0.053 mg/mL), of the samples was also higher in methanolic extracts. The capacity for chelating metal ions was higher in aqueous extracts (41.11-82.35%) than in the methanolic ones (4.33-29.68%). Propolis from three locations of Algarve region were richer in phenols and had better capacity for scavenging free ABTS and DPPH radicals than the remaining samples. These places are part of a specific zone of Algarve known as Barrocal.