以奈米乳液包埋多甲氧基黃酮提高其儲存安定性及生物利用率

Abstract

根據數據統計顯示全球柑橘類水果的產量極高，亦會產生大量的副產物如柑橘皮。經文獻證明柑橘皮含有大量的多甲氧基黃酮（polymethoxyflavones , PMFs）且具有多種有效的生理活性如可以抗發炎、抗粥狀動脈硬化、抗惡性腫瘤等。然而多甲氧基黃酮本身具有兩個以上的疏水性甲氧基，與其他高疏水性化合物一般，有著高熔點、低溶解度及低生物可利用率之缺點，故食品工業中欲使用多甲氧基黃酮作為營養保健品存在很大的挑戰。奈米乳液是一種以油相、水相及乳化劑所組成的口服藥物遞送系統，其獨特的物化特性及功能性，可提高疏水性活性物質的溶解度及生物可利用率。故本研究目的即利用中鏈脂肪酸為油相，大豆分離蛋白為乳化劑製備穩定性佳的奈米乳液並包覆PMFs，以提升生物可利用率及其穩定性。本實驗先利用高速均質機25000 rpm攪打兩分鐘使不互溶的兩相形成均一的粗乳液，再以高壓均質機750 bar的高能量製備奈米乳液，並依據乳液粒徑大小、黏度特性及包覆效率挑選出最適合的配方及加工條件，隨後將其進行環境壓力測試，結果發現經過75oC加熱30分鐘後其粒徑大小依然小於500 nm且無凝乳的現象發生，此結果說明以巴氏殺菌處理後不會影響其穩定性；此外，經過28天長期儲藏試驗後，包覆效率依然維持在90% 以上。後續以脂解實驗可得知PMFs奈米乳液於胃腸道消化後所釋放的生物可接收度為42.6% 相對於PMFs中鏈脂肪酸懸浮液的17.9% 而言有顯著性的差異（p < 0.05），結果說明PMFs經奈米乳液包覆後可提升在小腸腔中溶解度。消化後的PMFs混合膠束利用Caco-2單層膜模型進行體外模擬小腸吸收試驗，結果證實具有更優的腸滲透性，整體而言，PMFs以混合膠束的形式相較於水溶液而言可更有效率穿透腸上皮細胞進入循環系統。綜合上述結果，此配方製備的奈米乳液具有優良的穩定性及包覆效率，可改善PMFs難以被人體消化吸收的特性。本實驗結果期望能提升多甲氧基黃酮於營養保健食品的適用性。

Polymethoxyflavones （PMFs）, found almost exclusively in citrus fruit, have been documented with strong biological efficacies, such as chronic inflammation, tumor development, atherosclerosis. PMFs is a group of hydrophobic phytochemicals with low water-solubility and, thus, poor bioavailability when consume orally.These problems cause limitation of its practical application in the food systems.To overcome the poor oral bioavailability, nanoemulsion system is commonly utilized to enhance the aqueous solubility, stability, and bioaccessibility of PMFs. Instead of synthetic emulsifier, soy protein isolate was used as the surface active agent for the production of nanoemulsion system. To produce the nanoemulsion, various ratios of MCT, soy protein isolate and water was first mixed with high speed homogenizer at 25000 rpm in 2 minutes. Later, nanoemulsion was generated through passing the coarse emulsion from high speed homogenization to high pressure homogenization at 750 bar. To find the optimum concentration in the nanoemulsion system, every ratio of material was prepared for nanoemulsion and determined based on the change in particle size, apparent viscosity and encapsulation efficiency. After environmental stress test and long-term storage test, the datas showed that soy protein-based nanoemulsion remained high satbility and encapsulation efficiency. The oral bioavailability of PMFs was also found significantly enhanced thorugh soy protein-based nanoemulsin system as evaluated by in vitro lipolysis and Caco-2 monolayer models. The result from this work demonstrated a successful incorporation of PMFs to a nanoemulsion, in which outstanding stability and oral bioavailability was made possible.