Six new triterpenes (1- 6) and four known compounds have been isolated from dried stems and leaves of Melissa officinalis. The known compounds were identified as quadranoside III, salvianic acid A, rosmarinic acid, and luteolin. The structures of compounds 1- 6 were established by analysis of spectroscopic data. Free radical scavenging and antimicrobial activities of the extracts and of rosmarinic acid, the major component, were evaluated.
Rhodiola rosea L. (Crassulaceae) is a plant living at high altitudes in Europe and Asia. Its roots have long been used in the traditional medical system of these geographical areas to increase the organism resistance to physical stress; today, it has become an important component of many dietary supplements. In this study we investigate the antioxidant capacity of the R. rosea aqueous extract evaluating its ability to counteract some of the main damages induced by hypochlorous acid (HOCl), a powerful oxidant generated by activated phagocytes, to human erythrocytes. Ascorbic acid was used as a reference substance because of its physiological HOCl-scavenging ability. Our study demonstrates that R. rosea is able to significantly protect, in a dose-dependent manner, human RBC from glutathione (GSH) depletion, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) inactivation and hemolysis induced by the oxidant. Furthermore, we demonstrate that R. rosea aqueous extract acts from the inside of the erythrocyte suggesting a probable involving of cell components. The protection on GSH afforded by the R. rosea extract with respect to ascorbic acid, occurred also if added 2 or 5 min. later than the oxidant, suggesting a more rapid or powerful effect.
Keratinocytes are cells strongly exposed to oxidative stress, but normally good equipped for antioxidant responses. However, it has long been suggested that exogenous antioxidants could play a useful role in minimizing the adverse skin responses associated with such oxidant species. In this work it was paid attention to the extract of Rhodiola rosea L. roots by using the phytocomplex as a whole because of the important activity of its composition and mutual distribution of its components. We have measured the protection afforded by the extract to reduced glutathione levels, glyceraldehyde-3-phosphate dehydrogenase activity, and thiobarbituric acid reactive substances levels in cultured human keratinocytes (NCTC 2544) exposed to different oxidative insults: Fe(II)/ascorbate, Fe(II)/H(2)O(2), and tert-butyl-hydroperoxide. We also have investigated the influence of the R. rosea extract on the production of intracellular reactive oxygen species and on the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase). Furthermore, we have demonstrated that R. rosea extract was able to increase in a time- and dose-dependent manner the activity of the trans plasma membrane oxido reductase activity as an indirect evaluation of the intracellular redox status and this effect was already evident with small concentration of the extract and in a long time. As a result, NCTC 2544 are able to better counteract to several oxidative insults if incubated with R. rosea extract demonstrating a very good antioxidant activity of this phytocomplex.
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