Antioxidant and antihemolytic activities of flavonoid rich fractions of Artemisia tschernieviana Besser.

OBJECTIVES: Artemisia (Asteraceae) contains more than 400 species. Many of the plants belonging to this genus are known to possess biological properties. In this study, antioxidant and antihemolytic activities of flavonoid rich fractions of A. tschernieviana Besser were evaluated. MATERIAL AND METHODS: Plant aerial parts were extracted with 60% acetone. Extract was fractionated sequentially with hexane (HE), ethyl acetate (EA) and water (AQ). Antioxidant and antihemolytic activities of these fractions were assessed. Their antihemolytic activity was determined by H2O2 and cumene hydroperoxide induced hemolysis models. RESULTS: AQ fraction showed very powerful activity in 1,1-disphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity with IC50 = 0.12 +/- 0.01 microg ml(-1) that was better than controls (vitamin C, quercetin and butylated hydroxyanisole (BHA)). This fraction showed very powerful reducing power assay that was better than vitamin C (p < 0.01). EA fraction showed higher activity in scavenging nitric oxide with IC50 = 0.14 +/- 0.04 microg ml(-1). In iron chelating activity HE fraction showed the best activity (IC50 = 162.2 +/- 8.7 microg ml(-1)). In scavenging of hydrogen peroxide, AQ fraction showed better activity than control group. This fraction had higher phenol and flavonoid contents. EA fraction showed higher antihemolytic activity with IC50 = 728.8 +/- 29 microg ml(-1). CONCLUSIONS: The fractions show very good activities in studied models. Aqueous fractions showed better activity than the others in nearly all tested models. These results can be useful as a starting point of view for further applications of A. tschernieviana aerial parts or its constituents in pharmaceutical preparations after performing clinical in vivo researches.

Stomatal vs. genome size in angiosperms: the somatic tail wagging the genomic dog?

BACKGROUND AND AIMS: Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the primary determinant of genome size. Stomata are crucial for photosynthesis and their size affects functional efficiency. METHODS: Stomatal and leaf characteristics were measured for 1442 species from Argentina, Iran, Spain and the UK and, using PCA, some emergent ecological and taxonomic patterns identified. Subsequently, an assessment of the relationship between genome-size values obtained from the Plant DNA C-values database and measurements of stomatal size was carried out. KEY RESULTS: Stomatal size is an ecologically important attribute. It varies with life-history (woody species < herbaceous species < vernal geophytes) and contributes to ecologically and physiologically important axes of leaf specialization. Moreover, it is positively correlated with genome size across a wide range of major taxa. CONCLUSIONS: Stomatal size predicts genome size within angiosperms. Correlation is not, however, proof of causality and here our interpretation is hampered by unexpected deficiencies in the scientific literature. Firstly, there are discrepancies between our own observations and established ideas about the ecological significance of stomatal size; very large stomata, theoretically facilitating photosynthesis in deep shade, were, in this study (and in other studies), primarily associated with vernal geophytes of unshaded habitats. Secondly, the lower size limit at which stomata can function efficiently, and the ecological circumstances under which these minute stomata might occur, have not been satisfactorally resolved. Thus, our hypothesis, that the optimization of stomatal size for functional efficiency is a major ecological determinant of genome size, remains unproven.