RESUMO
Lichens are symbiotic associations of fungi with microalgae and/or cyanobacteria, which are considered among the slowest growing organisms, with strong tolerance to adverse environmental conditions. There are about 400 genera and 1600 species of lichens and those belonging to the Usnea genus comprise about 360 of these species. Usnea lichens have been used since ancient times as dyes, cosmetics, preservatives, deodorants and folk medicines. The phytochemistry of the Usnea genus includes more than 60 compounds which belong to the following classes: depsides, depsidones, depsones, lactones, quinones, phenolics, polysaccharides, fatty acids and dibenzofurans. Due to scarce knowledge of metabolomic profiles of Usnea species (U. barbata, U. antarctica, U. rubicunda and U. subfloridana), a study based on UHPLC-ESI-OT-MS-MS was performed for a comprehensive characterization of their secondary metabolites. From the methanolic extracts of these species a total of 73 metabolites were identified for the first time using this hyphenated technique, including 34 compounds in U. barbata, 21 in U. antarctica, 38 in U. rubicunda and 37 in U. subfloridana. Besides, a total of 13 metabolites were not identified and reported so far, and could be new according to our data analysis. This study showed that this hyphenated technique is rapid, effective and accurate for phytochemical identification of lichen metabolites and the data collected could be useful for chemotaxonomic studies.
Assuntos
Líquens/química , Metabolômica/métodos , Extratos Vegetais/análise , Espectrometria de Massas em Tandem/métodos , Usnea/química , Usnea/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Fungos , Metanol/química , Compostos Fitoquímicos/metabolismo , Extratos Vegetais/químicaRESUMO
Lichen, Usnea barbata, transplants taken from Tierra del Fuego (south Patagonia, Argentina) were tested as potential biomonitors of atmospheric airborne deposition in an apparently pristine environment. In 2005, lichens were sampled in a reference site (n = 31) and transplanted in the northern Region of Tierra del Fuego. After, respectively, 1 month and 1 year of exposure, we collected them. The aim of the study was to determine the bioaccumulation of 26 elements in order to evaluate the background levels in the selected area. Samples were analyzed by the sector field inductively coupled plasma mass spectrometry. Discriminant analysis on principal component analysis factors was applied in order to explore the relationship among the different elements as far as time and spatial variation in transplants regards. The analysis was tested by Monte Carlo test based on 999 replicates. The most important contamination source resulted to be the atmospheric soil particle deposition. Furthermore, the results were compared with those obtained from the lichens collected in central and southern Tierra del Fuego. This study confirms the ability of U. barbata to reflect the background levels of the 26 elements in that environment. Compared with other background sites in the world, we did confirm that Tierra del Fuego lichens have a low content of the studied elements. Tierra del Fuego turned out not to be a pristine environment as supposed, but it can be considered as a reference basal ecosystem for useful comparisons among different geographical areas. These findings can be very relevant and useful for environmental conservation programs.
Assuntos
Poluentes Atmosféricos/química , Monitoramento Ambiental/métodos , Oligoelementos/química , Usnea/metabolismo , Argentina , AtmosferaRESUMO
In the present study, the effect of nickel incorporation on the chemical response of Ramalina celastri (Spreng.) Krog & Swinsc. and Usnea amblyoclada (Müll. Arg.) Zahlbr. exposed to urban atmospheric pollutants was assessed. Lichen thalli were treated with Ni solutions and then transplanted to two areas of the city of Córdoba with different levels of pollution. After exposure, the concentration of chlorophyll a, chlorophyll b, phaeophytin a, hydroperoxy conjugated dienes, malondialdehyde, sulphur content, electric conductivity of the immersion water, and nickel content were measured. Also, a Pollution Index was calculated for each lichen species. The exposure to Ni altered the physiological response to atmospheric pollutants in both lichen species, making them more sensitive to any damage caused by them. When the species were compared, it was observed that R. celastri accumulated more sulphur than U. amblyoclada.
Assuntos
Poluentes Atmosféricos/toxicidade , Líquens/efeitos dos fármacos , Níquel/toxicidade , Usnea/efeitos dos fármacos , Líquens/metabolismo , Níquel/metabolismo , Usnea/metabolismoRESUMO
The effect of Cu2+, Ni2+, Pb2+, and Zn2+ on some physiological parameters of the lichen Usnea amblyoclada and the selective uptake of Cu2+ and Pb2+ was assessed. Fresh thalli were soaked in single or mixed metallic solutions. The concentration of chlorophylls and malondialdehyde; the dry weight/fresh weight ratio as well as the water content and the concentration of Cu, Ni, Pb, and Zn were measured in the treated and control thalli. The exposure to Cu, Ni, and Pb solutions caused several changes on the parameters measured; no differences were found with Zn. A stronger ability for binding Pb2+ was also observed. The results suggest that Cu2+ was the most harmful cation followed by Pb and Ni. Consequently, the damage observed in U. amblyoclada thalli when it is used as a biomonitor in polluted areas is possibly due to the presence of these heavy metals, masking the effect of other gaseous pollutants.