| Abstract: | 洛神花(Hibiscus sabdariffa linnaeus)為錦葵科(Malvaceae)植物，原產熱帶地區，分部於印度，馬來西亞及東南亞，台灣東部及南部也盛產。其花成份包含有機酸(如檸檬酸、壞血酸、原兒茶酸等)；醣分主要為半乳糖，葡萄糖及果糖；Pectin及類黃酮素，黃酮素包括有Hibiscetin，Gossypetin，Quercetin。國外之研究，在體外試驗顯示其水萃取物有Anti-spasmodic，降膽固醇，降血壓及抗菌作用。其成份Flavonoids具有抗氧化及抑制心血管疾病；原兒茶酸(Protocatechuic acid；PCA)可抑制化學致癌物誘導之癌化，本研究室也顯示洛神花中之PCA及花青素有強的抗氧化作用，另外PCA亦有抗TPA促腫瘤作用及促進HL-60凋謝死亡之作用。在上一年度(90年度)，本研究計畫顯示洛神花水萃取物(Hibiscus sabdariffa extract, HSE)具有抑制LDL氧化作用，並以高果糖誘發SD大白鼠產生高血脂症及以lard oil餵食兔子產生高血脂症的實驗模式證實洛神花水萃取物具有降低高血脂及抑制Atherosclerosis lesion的作用。而本年度的研究內容則在於探討HSE對動脈粥狀硬化抑制的可能機轉。我們以RAW264.7巨噬細胞為實驗模式，並以銅離子誘發LDL氧化加入巨噬細胞中，結果發現100μg/ml的LDL被誘發成OxLDL後，會使得巨噬細胞死亡，並且這種死亡形式為程式型死亡(Apoptosis)。而預處理HSE依劑量逐漸增高(0.01, 0.03, 0.05, 0.1, 0.5 mg/ml)對這種死亡的現象抑制情形也越明顯，包括細胞型態在0.5 mg/ml時可將細胞型態恢復為與未處理者相同，而隨著HSE的濃度增高，將有效地減低DNA fragmentation的程度、Caspase-3 activity及PARP蛋白斷裂等Apoptosis的現象，同時我們也發現HSE有抑制Macrophage migration的現象。由此我們推測HSE抑制動脈粥狀硬化的作用機轉可能在於抑制氧化型LDL使巨噬細胞死亡或Migration以減低動脈脂肪斑塊(Fatty steak)形成的速率，藉此達到抑制動脈粥狀硬化的作用。
Hibiscus sabdariffa Linne (Malvaceae), an attractive plant believed to be native to Africa is cultivated in Sudan and in eastern and Taiwan. It has been reported to contain a number of flavonoids including gossypetin, hibiscetin and quercetin. In vitro experimental studies have shown that administration of the aqueous extract produces anti-inflammation, hypotensive and hypocholesterolemic. In spite of the wide use of H. sabdariffa extract (HSE) in folk medicine for treating various diseases, there is no report in the literature on their anti-atherosclerosis activity. In previous study, we have proved HSE can inhibit the production of OxLDL, and can inhibit hyperlipidaemic or atherosclerosis in animal model. But, the mechanisms on HSE inhibiting atherosclerosis were not clarified. In this study, we find that Cu/sup 2+/-induced OxLDL cause RAW264.7 macrophage death. Interistingly, HSE can rescue effectively on OxLDL-induced cell apoptosis in dose-dependent. Furthermore, we used some apoptosis criteria including cell morphology, DNA fragmentation, caspase-3 activity and PARP protein cleavage to evaluate the effect on HSE-reducing macrophage death. In these experiments, HSE showed powerful potential to inhibit cell apoptosis. Moreover, we also found HSE can inhibit macrophage migration. According to above, we assumed the mechanisms on HSE-inhibiting atherosclerosis could be via inhibiting OxLDL-induced macrophage death and migration. In this way, the rate on fatty steak formation will be slowed down, and athersocleretic progress will also be suppressed. |
