Protection of glycyrrhizic acid against AGEs-induced endothelial dysfunction through inhibiting RAGE/NF-¦ÊB pathway activation in human umbilical vein endothelial cells

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• 作者：Liang Feng^a ; ^{wenmoxiushi@163.com} ; Mao-mao Zhu^a ; Ming-hua Zhang^a ; Ru-shang Wang^b ; Xiao-bin Tan^a ; Jie Song^a ; Shu-min Ding^a ; ^c ; Xiao-bin Jia^a ; Shao-ying Hu^a
• 关键词：AGEs advanced ; glycation end products ; ROS ; reactive oxygen species ; GA ; glycyrrhizic acid ; HUVECs ; human umbilical vein endothelial cells ; AO/EB ; acridine orange/ethidium bromide ; BSA ; non-glycated bovine serum albumin ; AG ; aminoguanidine ; VE ; Vitamin E
• 刊名：Journal of Ethnopharmacology
• 出版年：2013
• 出版时间：21 June, 2013
• 年：2013
• 卷：148
• 期：1
• 页码：27-36
• 全文大小：5660 K

文摘

Ethnopharmacological relevance

Licorice (Glycyrrhiza uralensis roots) is used as a traditional medicine for the treatment of diabetes mellitus and its vascular complications. Glycyrrhizic acid (GA, also known as Glycyrrhizin), a triterpenoid saponin glycoside, is considered to be a bioactive component in Licorice and is beneficial to diabetic vascular complications.

Aim of study

The present study was conducted to evaluate the potential protective activities on AGEs-induced endothelial dysfunction, including anti-apoptosis, antioxidant stress and anti-proinflammatory responses, and explore the underlying mechanism.

Materials and methods

Human umbilical vein endothelial cells (HUVECs) were incubated and pre-treated with GA (10^?9-10^?6 M) or RAGE-Ab (5 ¦Ìg/ml) in the presence or absence of 200 ¦Ìg/ml AGEs. AO/EB fluorescence staining assay was performed to evaluate anti-apoptosis activity. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in cell supernatant were detected by kits while the intracellular reactive oxygen species (ROS) generation was determined by 2,7-dichlorodihydrofluorescin diacetate (DCFH-DA) kit. Immunocytochemistry analysis was designed to determine transforming growth factor beta1(TGF-¦Â1) protein expression while immunofluorescence analysis for RAGE and NF-kB. The protein expressions of TGF-¦Â1, RAGE and NF-kB were analyzed by Western blot analysis.

Results

Pretreatment with GA at a concentration of 10^?8-10^?6 M significantly reduced the AGEs-induced apoptosis in HUVECs. GA significantly increased antioxidant enzyme SOD activity and decreased peroxide degradation product MDA level in a dose-dependent manner. Furthermore, GA also remarkably inhibited the overgeneration of AGEs-induced ROS. Both immunocytochemistry analysis and western blot analysis showed that GA significantly decreased the protein expression of poinflammatory cytokine TGF-¦Â1 in a similar manner which RAGE-Ab did. Additionally, AGEs-induced RAGE and NF-kB protein expressions were down-regulated significantly by the pretreatment with GA or RAGE-Ab.

Conclusion

These findings provide evidences that GA possesses protective activity on AGEs-induced endothelial dysfunction, including anti-apoptosis, anti-inflammation and antioxidant stress, via inhibiting RAGE/NF-kB pathway. GA might be an alternative for the prevention and treatment of diabetic vascular complications in an appropriate dosage.