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Antioxidant activity of Pelargonium radula (Cav.) L'Herit and its effect on antioxidants level in glucose-induced oxidative stress

Pelargonium radula (Cav.) L’Hérit (Geraniaceae) is a decorative plant that originates from the Southeast of Africa. Leaf extracts of P. radula were found to have hypoglycaemic properties.1 Chronic hyperglycemia in diabetes leads to chronic oxidative stress in all tissues because glucose in abnormally high concentrations forms reactive oxygen species.2 Additionally, diabetes mellitus affects the synthesis rates of liver protein. Thus, the aim of this study was to evaluate if P. radula, besides its glucose-lowering properties, can have additional beneficial effects on diabetes. In order to establish the most appropriate method for antioxidants extraction, fresh and dried leafs were extracted either at 20 C (with either ethanol or water), or at 100 C with water. Since phenolic substances are reputed antioxidants, their content was determined in the extracts (total phenols, flavonoids, tannins and phenolic acids). Antioxidant activity was established as radical scavenging and chelating activity, reducing power and activity in -carotene-linoleic acid assay. To establish possible intracellular effects of the extracts, Hep G2 cells were incubated with 20 mM glucose and with different extracts in concentration of 25 g/mL. Concentration of total protein was determined using Quant-iT Protein Assay Kit. Results were compared using t-test and ANOVA with Dunett's post-hoc test (p < 0.05). Ethanolic extracts of fresh leaf contained the greatest amounts of flavonoids while the ethanolic extract of dry leaf had the greatest amount of other investigated phenols. The antioxidant activity of the investigated extracts did not correlate with content of evaluated phenolic compounds. In addition, aqueous extract of fresh leaves prepared at 100 C significantly increased protein synthesis in Hep G2 cells in comparison with cells treated only with glucose. The results of present study suggest that P. radula leaf might be useful as complementary therapy in diabetes.

Antioxidant; Pelargonium radula

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