| Abstract: | 血液中高濃度的血糖會引發自由基的產生進而造成視網膜病變。我們之前的研究已經證實洛神花水萃取物與多酚萃取物可以減緩streptozotocin(STZ)誘發的糖尿病視網膜病變。在這次的研究，我們將進一步檢測洛神花水萃取物中的多酚化合物protocatechuic acid、catechin、ferulic acid、gallic acid、quercetin與epicatechin等成份，分別對於高血糖處理下之人類視網膜色素上皮細胞的影響。結果發現以高濃度葡萄糖(25mM)培養六天，視網膜色素上皮細胞數量明顯增加並呈現dose-depedent manner。若同時分別添加10μM protocatechuic acid、quercetin、ferulic acid、catechin、gallic acid與epicatechin則細胞數會明顯減少，依次為51.78 %、37.4 %、30.27 %、30.07%、22.93%、32.47%。我們進一步分析細胞內PKC-α、PKC-δ與PKC-λ蛋白的變化，但都沒有明顯改變。我們另外將視網膜色素上皮細胞處理48小時發現MMP-2活性明顯增加。同時分別加10μM protocatechuic acid、quercetin與ferulic acid則MMP-2活性明顯減少，依次為25.9%、14.8%、5.9%。雖然protocatechuic acid、quercetin、ferulic acid、catechin、gallic acid與epicatechin都可以減緩高濃度葡萄糖誘導的人類視網膜色素上皮細胞增生但未來機轉仍有待釐清。
High level of blood glucose could produce reactive oxygen species (ROS) to cause retinopathy. Our previous study demonstrated that Hibiscus sabdariffa aqueous extracts (HSE) and Hibiscus sabdariffa polyphenols extracts (HPE) could decelerate retinopathy in streptozotocin (STZ)-induced diabetic rats. In this study, we further examined the effect of protocatechuic acid, catechin, ferulic acid, gallic acid, quercetin and epicatechin existing in HSE in high glucose treating human retinal pigment epithelial (RPE) cells. We found that after treatment of high glucose (25 mM) for at least 6 days, RPE cells showed a significant increase in a dose-dependent manner. As accompanied with treatment of 10μM concentration of protocatechuic acid, quercetin, ferulic acid, catechin, gallic acid and epicatechin the increased cell could be reduced up to 51.78%, 37.4 %, 30.27 %, 30.07 %, 22.93%, 32.47%, respectively. We further examined the expressions of PKC-α, PKC-δ, PKC-λ. But, there were no significant changes in these proteins. We examined that after treatment of high glucose (25 mM) for 48 hrs, RPE cells showed the activity of MMP-2 significant increase.As accompanied with treatment of10μM concentration of protocatechuic acid, quercetin and ferulic acid the increased MMP-2 activity could be reduced to 25.9%, 14.8%, 5.9%, respectively.
In conclusion, protocatechuic acid、quercetin、ferulic acid、catechin、gallic acid and epicatechin could reduce high glucose induced RPE cell proliferation, but the mechanisms should be further clarified. |
