Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Evaluation of the antioxidant activity of cell extracts from microalgaePublication . Guedes, A. Catarina; Gião, Maria S.; Seabra, Rui; Ferreira, Antonio; Tamagnini, Paula; Moradas-Ferreira, Pedro; Malcata, F. XavierA growing market for novel antioxidants obtained from non-expensive sources justifies educated screening of microalgae for their potential antioxidant features. Characterization of the antioxidant profile of 18 species of cyanobacteria (prokaryotic microalgae) and 23 species of (eukaryotic) microalgae is accordingly reported in this paper. The total antioxidant capacity, accounted for by both water- and lipid-soluble antioxidants, was evaluated by the (radical cation) ABTS method. For complementary characterization of cell extracts, a deoxyribose assay was carried out, as well as a bacteriophage P22/Salmonella-mediated approach. The microalga Scenedesmus obliquus strain M2-1 exhibited the highest (p > 0.05) total antioxidant capacity (149 ± 47 AAU) of intracellular extracts. Its scavenger activity correlated well with its protective effects against DNA oxidative damage induced by copper(II)-ascorbic acid; and against decay in bacteriophage infection capacity induced by H2O2. Finally, performance of an Ames test revealed no mutagenic effects of the said extract.
- Supercritical fluid extraction of carotenoids and chlorophylls a, b and c, from a wild strain of Scenedesmus obliquus for use in food processingPublication . Guedes, A. Catarina; Gião, Maria S.; Matias, Ana A.; Nunes, Ana V. M.; Pintado, Manuela E.; Duarte, Catarina M. M.; Malcata, F. XavierFaster and more selective extraction methods are urged to recover food-grade pigments and antioxidants from microalgae - which do not resort to food-incompatible and environment-unfriendly solvents. Hence, this study ascertained the influence of pressure, temperature, CO2 flow rate and a polar co-solvent upon the yields of carotenoids and chlorophylls in supercritical fluid extraction of Scenedesmus obliquus biomass. The highest carotenoid yield was attained at 250 bar and 60 degrees C. The yields of chlorophylls, when using plain CO2, increased slightly with pressure, but decreased with temperature and CO2 flow rate; the highest yield of chlorophyll a was at 4.3 g(CO2), min(-1), whereas ethanol as co-solvent increased all yields except that of chlorophyll c. The highest ratio of total carotenoids to chlorophyll a was reached at 250 bar and 60 degrees C. A remarkable selectivity was observed under these operating conditions, which may enable easy separation and purification of the aforementioned pigments.