超臨界二氧化碳萃取薏苡麩皮及其對餵食高脂食物倉鼠之降血脂活性機轉研究

薏仁（Adlay Seed）為禾本科植物薏苡 Coix lacryma-jobi var. mayuren 之種仁，在中國本草學上，記載著具有抗發炎、抗氧化、抗過敏、抗菌、降血脂、解熱、鎮痛、促進免疫等之功效。薏苡麩皮含高量油份，在相關研究中發現其有效成分為脂溶性，因此本研究使用薏苡麩皮作為原料，以超臨界CO2萃得CO2粗萃物，再以超臨界CO2進行分餾，從CO2粗萃物再分餾得到兩個檢品，分別標定為CO2分餾塔頂餾出液與CO2分餾塔底餾餘液，將連同CO2粗萃物等檢品進行降血脂之生物活性品質評價研究。研究目的在於探討飲食條件為高脂肪、高膽固醇時，投予經過超臨界CO2萃取以及分餾之三種不同檢品，對倉鼠體內血液脂肪代謝與調節影響。動物實驗模式以高脂食物餵食倉鼠，誘發血脂升高，並同時將檢品以胃管餵食倉鼠。結果顯示餵食28天高脂食物後，高脂對照組倉鼠血液中三酸甘油脂、總膽固醇、低密度膽固醇、極低密度膽固醇、動脈硬化指數之值皆顯著高於控制組，實驗組方面，CO2粗萃物及CO2分餾塔頂餾出液實驗組在Total-Choleterol、LDL-Cholesterol、VLDL-Cholesterol之表現與對照組比較，有明顯的降低效果（P<0.05），而CO2分餾塔頂餾出液實驗組對HDL-Cholesterol之表現與對照組比較，有明顯的上升效果（p<0.05）。肝均質液生化檢測亦顯示選取CO2粗萃物以玉米油稀釋做不同劑量投予，三組劑量500 mg/kg、1000 mg/kg、3000 mg/kg與高脂對照組比較，有降低脂質過氧化物MDA之量與提升麩胱苷肽（GSH）之活性。此外，各檢品投予組糞便中性脂肪之檢測與高脂對照組比較均無任何改變，但糞便膽酸與對照組比較則有明顯的上升（p<0.05）。由實驗結果得知超臨界CO2流體萃取薏苡麩皮可取得降血脂的活性，其降血脂之機轉研究顯示薏苡麩皮超臨界CO2萃取物不具有抑制腸道脂肪的吸收，但可加速肝臟代謝膽固醇成膽酸而從腸道排出體外，亦有可能為抑制肝臟膽固醇的合成，據此觀之，薏苡麩皮超臨界CO2萃取物具有發展成降血脂健康食品之潛力。

關鍵字

超臨界二氧化碳；薏苡；降血脂

並列摘要

Adlay ( Scientific name：Coix lachryma-jobi var. mayuren) is a grass crop that has long been used in traditional Chinese medicine and as a nourishing food. The seed of adlay has been reported to exhibit anti-inflammatory, anti-oxidant, allergic resistent, antibiotic, stomachic, diuretic, antispastic, plasma lipids lowering, immunity effects promoting in vivo. Because the active components of adlay seed bran have been found in fat-soluble fraction, we used supercritical fluid technology to extract these components in the present study and obtained three different fractionative oils --- CO2 crude extract oil, CO2 Distillate Oils from Fracitonation and CO2 Raffinate Oils from Fracitonation. According to the results of hypercholesterol-diet hamsters, the CO2 crude extract oil and CO2 upper-layer oil treated groups significantly reduced the plasma total cholesterol, LDL, VLDL, but elevated HDL. In liver homogenates, ready with CO2 crude extract oil and CO2 Distillate Oils from Fracitonation reduced LDL level, MDA level, but elevated glutathione concentration. In addition, the levels of neutral lipids in hamster’s stool were unchanged in test groups, but the bile acid concentrations in test articles groups were significantly elevated. According to the results, using supercritical fluid technology to extract adlay seed bran was successful and the crude extracts showed anti-hyperlipidemia effect against hypercholesterol-diet hamster. The results showed that crude extract oil of adlay seed bran can’t inhibit the lipids absorption in GI tract, but it can increase the degradation rate from cholesterol to bile acid in liver. Furthermore, the extract of adlay seed bran exhibited anti-oxidant effect to protect tissue damage induced by free radicals. These results suggested that the supercritical fluid extract of adlay seed bran has potent anti-hyperlipidemia health food in the future.