Study on the Bioavailability and Metabolism of Nano/sub-microsized Lignan Glycosides from Sesame Meal
|Keywords:||奈米科技;lignan glycosides;芝麻粕;生物可利用率;代謝物;抗氧化活性;Nanotechnology;lignan glycosides;sesame meal;bioavailability;metabolites;antioxidative activity||Issue Date:||2010||Abstract:||
奈米科技在近年來快速發展，然而有關奈米化食品之生物可利用率及代謝等方面的研究仍非常有限。芝麻粕是芝麻油提取過程中之副產物，本研究以芝麻粕中的lignan glycosides (LGSM)粗萃物為試驗材料，進行奈米化研究。以直徑0.3 mm之鋯珠為研磨介質，在攪拌軸轉速3600 rpm下研磨30分鐘後，LGSM (1%水懸浮液)之平均粒徑可由2 μm降至200 nm左右。在安定性試驗中，以沉澱物高度、濁度、界面電位及粒徑分佈等物性指標評估，觀察4℃下儲存14天過程中，界面活性劑對LGSM懸浮液安定性之影響。結果以添加1-2%蔗糖酯(HLB=11)之效果最佳，有助穩定奈米/次微米懸浮液。以Caco-2細胞單層膜模式評估LGSM主成分sesaminol triglucoside (ST)之腸道吸收情形，結果顯示奈米/次微米化後之通透率及吸收率均較高。在藥物動力學試驗中，分別以靜脈注射及胃管餵食之方式投予大鼠奈米/次微米化前、後之LGSM，再以HPLC分析血漿中ST濃度，結果發現奈米/次微米化LGSM組別中ST之血漿中最大濃度、血漿濃度-時間曲線下面積及生物可利用率均較高，未奈米化與奈米/次微米化組別中ST之生物可利用率分別為0.18±0.03%及0.26±0.04%。此外，大鼠體內組織分佈試驗中發現，在多數器官中，尤其是肝臟與小腸，ST及其代謝物(sesaminol、sesaminol sulfate、sesaminol glucuronide、enterodiol與enterolactone)濃度皆以奈米/次微米化LGSM組別較高。在大鼠排除試驗中發現，胃管餵食後8-12 hr為ST之最大排除期，奈米/次微米化LGSM組別之ST及其代謝物濃度，在尿液中較高、糞便中較低。本研究結果顯示奈米/次微米化有助提升LGSM之生物可利用率。此外，在特丁基過氧化氫(tert-butyl hydroperoxide)誘導大鼠氧化傷害模式試驗中，LGSM及奈米/次微米化LGSM皆具抗氧化活性，以800 mg/kg bw之劑量餵食30天，可降低大鼠肝臟與血漿中丙二醛(malondialdehyde)含量，提高肝臟中麩胱甘肽過氧化酶(glutathione peroxidase)、麩胱甘肽還原酶(glutathione reductase)與過氧化氫酶(catalase)活性，其中又以奈米/次微米化LGSM之抗氧化活性較佳，可能因其生物可利用率較高所致。
Recently nanotechnology is quickly developing. However, research on bioavailability and metabolism of nanofoods are quite limited. Sesame meal is the by-product of the extracting process of sesame oil. In this study, crude extract of lignan glycosides from sesame meal (LGSM) was the material to be nanosized. Zirconium bead with 0.3 mm diameter was the milling media employed. The average particle size of 1% LGSM aqueous suspension reduced rapidly from around 2 μm to 200 nm after media milling with agitation speed at 3600 rpm for 30 min. In the stability study, the effect of surfactants on LGSM nano/sub-microsuspension stored at 4℃ for 14 days was investigated by sediment height, turbidity, zeta potential and particle size distribution. Results showed that 1-2% sugar ester (HLB=11) had the best effect to stabilize nanosuspension. In the Caco-2 cell monolayer model study, higher transport and absorption efficiency of sesaminol triglucoside (ST), which is the main component in LGSM, were found after nano/sub-microsizing. In the pharmacokinetic study, LGSM and nano/sub-microsized LGSM (N-LGSM) were administered separately to SD rats via intravenous injection and tube feeding. The plasma concentration of ST was assayed by HPLC method. Results showed that maximum concentration, area under plasma concentration-time curve and bioavailabilities of ST in N-LGSM were higher than those in LGSM. The bioavailability of ST in LGSM and N-LGSM were 0.18±0.03% and 0.26±0.04%, respectively. In the tissue distribution study, higher concentration of ST and its metabolites (sesaminol, sesaminol sulfate, sesaminol glucuronide, enterodiol and enterolactone) were found in N-LGSM in most organs, especially liver and small intestine. In the excretion study, the maximum excretion period of ST occurred 8-12 hr after tube feeding. The concentration of ST and its metabolites in N-LGSM were higher in urine and lower in feces compared to those in LGSM. This study clearly showed that LGSM is more bioavailable after nano/sub-microsizing. In addition, both LGSM and N-LGSM (800 mg/kg bw) had antioxidative activity against tert-butyl hydroperoxide-induced oxidative damage in SD rats. Treatment of LGSM or N-LGSM for 30 days reduced malondialdehyde level in liver and plasma and increased the activities of glutathione peroxidase, glutathione reductase and catalase in liver. N-LGSM had higher antioxidative activity than LGSM, which might be due to its higher bioavailability.
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