Aqueous Extract of Purple Sweet Potato Tuber Increases Sod And Decreases VCAM-1 Expression By Increasing Nrf2 Expression In The Aortic Endothelia Of Hypercholesterolemic Rabbits

Abstract

Aqueous extract of purple sweet potato tuber are supposed to prevent oxidative stress and protect endothelial function by unknown mechanisms. The purpose of this study was to prove the ability of purple sweet potato tuber aqueous extract in preventing oxidative stress through increasing superoxide dismutase (SOD) via Nrf2 upregulation and decreasing VCAM-1 expression in rabbit aortic endothelium. This study was experimental laboratoric study, with randomized post-test only control group design. The rabbits were randomized into 3 groups (6 rabbits per group). The control group was treated with standard diet, treatment 1 was treated with high-cholesterol diet, and treatment 2 was treated with high-cholesterol diet plus aqueous extract of purple sweet potato tuber with the dose of 4 mL/kg bw/day. After 12 weeks of treatment, blood samples were obtained for the examination of SOD, MDA and total cholesterol level. The expression of Nrf2, SOD-2 and VCAM-1 in aortic endothelium was evaluated based on immunohistochemical methods. One-way ANOVA  test were applied in data analysis, followed by path analysis. The results demonstrated significantly decreased MDA and increased blood SOD level, accompanied by statistically-significant increase in SOD-2 and Nrf2 expression, and decrease of VCAM-1 expression in the treatment group 2 compared to treatment group 1 (p <0.05). It can be concluded that the purple sweet potato tuber aqueous extract prevents oxidative stress by increasing the expression of SOD-2, via Nrf2 protein up-regulation, resulting in decreased VCAM-1 expression in the aortic endothelia of high-cholesterol diet-fed rabbits.

Keywords: Purple sweet potato, oxidative stress, SOD-2, Nrf2, VCAM-1, rabbit aorta