Vochysia rufa Stem Bark Extract Protects Endothelial Cells against High Glucose Damage

Abstract

Background: Increased oxidative stress by persistent hyperglycemia is a widely accepted factor in vascular damage responsible for type 2 diabetes complications. The plant Vochysia rufa (Vr) has been used in folk medicine in Brazil for the treatment of diabetes. Thus; the protective effect of a Vr stem bark extract against a challenge by a high glucose concentration on EA.hy926 (EA) endothelial cells is evaluated. Methods: Vegetal material is extracted with distilled water by maceration and evaporated until dryness under vacuum. Then; it is isolated by capillary electrophoresis-tandem mass spectrometry. Cell viability is evaluated on EA cells treated with 0.5-100 µg/mL of the Vr extract for 24 h. The extract is diluted at concentrations of 5, 10 and 25 µg/mL and maintained for 24 h along with 30 mM of glucose to evaluate its protective effect on reduced glutathione (GSH); glutathione peroxidase (GPx) and reductase (GR) and protein carbonyl groups. Results:V. rufa stem bark is composed mainly of sugars; such as inositol; galactose; glucose; mannose; sacarose; arabinose and ribose. Treatment with Vr up to 100 µg/mL for 24 h did not affect cell viability. Treatment of EA cells with 30 mM of glucose for 24 h significantly increased the cell damage. EA cells treated with 30 mM of glucose showed a decrease of GSH concentration and increased Radical Oxygen Species (ROS) and activity of antioxidant enzymes and protein carbonyl levels; compared to control. Co-treatment of EA with 30 mM glucose plus 1-10 μg/mL Vr significantly reduced cell damage while 5-25 μg/mL Vr evoked a significant protection against the glucose insult; recovering ROS; GSH; antioxidant enzymes and carbonyls to baseline levels. Conclusion:V. rufa extract protects endothelial cells against oxidative damage by modulating ROS; GSH concentration; antioxidant enzyme activity and protein carbonyl levels.

Keywords: Sapotaceae; Vochysia rufa; endothelial cells; oxidative damage; plant antioxidants.

Figure 1

Protective effect of Vochysia rufa bark extract on GSH levels of EA.hy926 cells treated with 30 mM glucose (Glu 30 mM) or 30 mM glucose plus noted concentrations of Vochysia rufa (Vr) extract or the positive control Epicatechin (EC). Values are means ± SD, n = 4. Values are expressed as nmol GSH/mg protein. Different letters indicate statistically significant differences (p < 0.05) among groups.

Figure 2

Protective effect of Vochysia rufa bark extract on GPx and GR activity of EA.hy926 cells treated with 30 mM glucose (Glu 30 mM) or 30 mM glucose plus noted concentrations of Vochysia rufa (Vr) extract or the positive control Epicatechin (EC). Values are means ± SD, n = 4. Values are expressed as a percent relative to activity of control condition. Different letters indicate statistically significant differences (p < 0.05) among groups. Letters in italics correspond to statistical significance in GPx.

Figure 3

Protective effect of Vochysia rufa bark treatment on carbonyl group production by EA.hy926 cells. Content of carbonyl groups was evaluated in EA.hy926 cells treated with 30 mM glucose (Glu 30 mM) or 30 mM glucose plus noted concentrations of Vochysia rufa (Vr) extract or the positive control epicatechin (EC). Values are means ± SD, n = 3. Values are expressed as a percent relative to control condition. Different letters indicate statistically significant differences (p < 0.05) among groups.