Rubus spp. (Rosaceae) provide extracts used in traditional medicine as antimicrobial, anticonvulsant, muscle relaxant and radical scavenging agents. Resistance to antibiotics used to treat Helicobacter pylori infection as well as their poor availability in developing countries prompted us to test the antimicrobial activity of Rubus ulmifolius leaves and isolated polyphenols against two H. pylori strains with different virulence (CagA+ strain 10K and CagA(-) strain G21). The antioxidant activity (TEAC values) of the tested compounds ranged from 4.88 (gallic acid) to 1.60 (kaempferol), whilst the leaf extract gave a value of 0.12. All the isolated polyphenols as well as the leaf extract showed antibacterial activity against both of the H. pylori strains. The minimum bactericidal concentrations (MBCs) of the extract for H. pylori strains G21 and 10K, respectively, were 1200 microg/mL and 1500 microg/mL after 24h of exposure and 134 microg/mL and 270 microg/mL after 48 h exposure. Ellagic acid showed very low MBC values towards both of the H. pylori strains after 48 h (2 microg/mL and 10 microg/mL for strains G21 and 10K, respectively) and kaempferol toward G21 strain (MBC=6 microg/mL). A relationship between antimicrobial activity and antioxidant capacity was found only for H. pylori strain G21 CagA(-) strain.

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Concentrations of major ions, silicate and nutrients (total N and P) were measured in samples of surface water from 28 lakes in ice-free areas of northern Victoria Land (East Antarctica). Sixteen lakes were sampled during austral summers 2001/02, 2003/04, 2004/05 and 2005/06 to assess temporal variation in water chemistry. Although samples showed a wide range in ion concentrations, their composition mainly reflected that of seawater. In general, as the distance from the sea increased, the input of elements from the marine environment (through aerosols and seabirds) decreased and there was an increase in nitrate and sulfate concentrations.Antarctic lakes lack outflows and during the austral summer the melting and/or ablation of ice cover, water evaporation and leaching processes in dry soils determine a progressive increase in water ion concentrations. During the five-year monitoring survey, no statistically significant variation in the water chemistry were detected, except for a slight (hardly significant) increase in TN concentrations. However, Canonical Correspondence Analysis (CCA) indicated that other factors besides distance from the sea, the presence of nesting seabirds, the sampling time and percentage of ice cover affect the composition of water in Antarctic cold desert environments.

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