粥狀動脈硬化是形成心臟血管疾病的一個重要病因，粥狀動脈硬化主要是因為血液中的膽固醇及低密度脂蛋白在血液的含量過高，受到自由基的氧化，形成氧化態的低密度脂蛋白，進而影響內皮細胞的增生及動脈粥狀斑塊的現象。在天然的抗氧化劑中，已清楚的報導具有抗動脈粥狀硬化的形成，例如Vit C、Vit E、beta-carotene。而在之前的研究中指出，洛神花水萃取物 (HSE) 和原兒茶酸 (PCA) 對氧化型低密度脂蛋白處理巨噬細胞 (RAW264.7) 具有抑制其凋謝死亡 (apoptosis) 的作用。
本實驗繼續探討洛神花水萃取物 (HSE) 及原兒茶酸 (PCA) 對氧化型低密度脂蛋白處理人類單核球細胞 (THP-1) 是否具有抑制其凋謝死亡的作用。利用脂質過氧化分析TBARS、Migration assay、Flow cytometric DNA fluorescence profiles等實驗方法，結果我們發現隨著洛神花水萃取物和原兒茶酸劑量的增加可以抑制由OxLDL所引起的細胞凋亡現象。結果在高濃度HSE及PCA，其抑制脂質過氧化物MDA的產生分別為91%及85%；migration assay中高濃度HSE及PCA可抑制migration分別為70%及76%；flow cytometry發現HSE及PCA抑制細胞凋謝死亡可達81%及93%。由以上結果得知，HSE或PCA可保護單核球細胞於處理oxLDL後分化為巨噬細胞的作用。
In developed countries, atherosclerosis and its complications are becoming a major cause of death. Several studies showed that free radical-mediated oxidation of low density lipoprotein leading to the production of oxidized LDL (OxLDL) is a key event in initiating endothelial cells proliferation and atherosclerosis plaque. Some natural antioxidants such as vitamin C, vitamin E, β-carotene have been revealed clearly to prevent the atherosclersis. As shown in previous studies, we found that the aqueous extract of Hibiscus Sabdariffa ( HSE ) and protocatechuic acid ( PCA ) could be able to inhibit the apoptosis of macrophage induced by OxLDL. In this study, we used the human monocyte, THP-1, to further detect the effects induced by OxLDL, and what kind of role could HSE and PCA play. Using TBAR, migration assay, flow cytometric DNA fluorescence and detecting apoptosis-related proteins, our results showed that increasing the dosage of HSE or PCA could inhibit monocyte apoptosis caused by OxLDL. At the high concentration of HSE and PCA, the concentrations of MDA produced from lipid peroxidation were inhibited up to 91% and 85%; the inhibitory percentage on migration were 70% and 76%; and the level of apoptosis was reduced to 81% and 93%. Taken the above, we concluded that the inhibitory mechanisms of HSE or PCA on atherosclerosis could also be contributed to the other pathway by inhibiting monocyte apoptosis and differentiation.
