埃及生產之苜蓿對降血脂及抗動脈粥狀硬化之研究   全文下載

Study of Hypocholesterolemic and Antiatherosclerotic Properties of Medicago sativa L. Cultivated in Egypt

苜蓿已被報導具有降血脂及抗動脈粥狀硬化之效果。成份中的皂素糖啟被視為重要因子，其藉由中和胃中膽固醇並促使其排出體外而達到上述功效。基於此因，苜蓿優於現所使用之抗血脂藥劑，該藥劑扮演著妨礙膽固醇合成體的角色。本研究嘗試製備高含量皂素及無/低量毒性成分之苜蓿萃取液，這些存在於天然苜蓿中之毒性成分（如刀豆胺基酸及coumestrol）會引發嚴重的副作用。國際市場亦有去毒苜蓿製藥之專利。本研究在不同生長階段中監測兩種不同埃及地區性苜蓿之皂素、刀豆胺基酸及coumestrol含量。結果顯示，受測萃取物有最高含量之皂素者（以降血脂及抗動脈粥狀硬化之效果評估）為地區A之果期狀態前階段；且此階段無刀豆胺基酸及coumestrol。研究證明，埃及生產之苜蓿可安全地降低天然膽固醇而擁有強效的抗動脈粥狀硬化能力。對於高血膽固醇實驗兔而言，該萃取物顯著降低總膽固醇及低密度膽固醇分別為85.1%及88%；其效果優於降膽固醇藥—gemfibrozil（73%及74%）。再者，苜蓿製品亦有顯著的抗氧化活性。經由高膽固醇膳食伴隨苜蓿萃取物餵食實驗，可發現實驗動物動脈幾乎正常；由此可知，所有的苜蓿萃取物均有抗動脈粥狀硬化之功效。

Alfalfa was reported to be hypocholesterolemic and antiatherosclerotic. Saponin glycosides were suggested to be responsible for this activity by neutralizing cholesterol in the stomach, enabling it to be excreted from the body. This makes alfalfa superior to the current anti-cholesterol medications which act by blocking cholesterol synthesizing apparatus. This study was undertaken in an attempt to prepare an alfalfa extract with high saponin content and free or low content of other toxic constituents found in alfalfa (canavanine and coumestrol), which causes serious side effects. A patent process was used to render alfalfa toxin free and to produce a drug present in the international market. Our study is based on monitoring the Egyptian crop at two different localities for its saponin, canavanine and coumestrol contents at different growth stages. The study showed that the tested extract of the chosen stage to be biologically studied (hypocholesterolemic and antiatherosclerotic effects) on the basis of the highest saponin content was just before fruiting stage of the locality A. This stage was free from both coumestrol and canavanine. The study proved that the Egyptian crop of alfalfa was found to safely reduce natural cholesterol and to possess a strong antiatherosclerotic activity. This extract (I) produced the most significant decrease in total cholesterol and LDL-cholesterol by 85.1 and 88%, respectively, of the corresponding levels in hypercholesterolemic rabbits. This decrease is more significant than that produced by gemfibrozil (73 and 74%) upon concomitant administration with a cholesterol enriched diet using the same animal model at the tested dose level. Also, it was obvious that all alfalfa preparations produced significant antioxidant properties. All alfalfa extracts possessed antiatherosclerotic activity as observed by the almost normalization of the aortic sections upon concomitant use of alfalfa extracts with cholesterol-enriched diet.