機能性卵繫帶水解物製備與慢性酒精攝取下肝臟保護功效探討

繫帶是液蛋製造過程中產生之副產物被視為廢棄物處理，本研究的主要目的在於以酵素水解繫帶，並分析水解產物之機能性與評估其開發成為機能性食品之潛力。研究的第一部分：繫帶在超音波震盪處理下以三種商業酵素（pepsin、protease A、與prozyme 6）以不同水解時間和酵素受值比下進行反應，最後篩選出繫帶在protease A在酵素受質比1:100 （w/w）、水解0.5小時為最適當條件，且具有最佳體外抗氧化力與產率，並以CCH-A（crude chalaza hydrolysates hydrolyzed by protease A, CCH-A）稱之。CCH-A經由蛋白質電泳發現具有小於12 kDa之胜肽片段以及富含游離胺基酸（Leu、Arg、Phe、Val、Lys、taurine）及機能性雙胜肽（anserine carnosine）。研究第二部分選用酒精誘導氧化壓力上升之小鼠模型進行CCH-A體內試驗。18隻8週齡雄性之C57BL/6小鼠隨機分為CON（control liquid diet + normal saline）、ALC （ethanol liquid diet + normal saline）、與ALC+CCH-A（ethanol liquid diet + 100 mg CCH-A/kg BW）等三組，並進行八週試驗。結果顯示：ALC+CCH-A組其腹部脂肪墊與肝臟之相對重量顯著小於ALC組（p<0.05），而在病理切片與分析肝臟之脂質亦發現，補充CCH-A可顯著減少脂肪小滴與脂肪含量之堆積（p<0.05），同時提昇與脂質氧化相關基因（Pparα、Cpt1、以及Ucp2）之表現（p<0.05），而脂質合成之相關基因也有減緩之趨勢，除此之外糞便中排出之脂質也顯著多於ALC組。另一方面在補充CCH-A下可顯著（p<0.05）提昇血清與肝臟中之總抗氧化能力與減緩氧化壓力，並顯著提昇肝臟之抗氧化防禦系統之能力（p<0.05）、以及有效減緩肝臟中細胞激素之含量（p<0.05）。綜上所述，本研究成功從繫帶副產物中水解出具有機能性之CCH-A，且於慢性酒精攝取下補充CCH-A，改善慢性酒精攝取下對肝臟造成的傷害。

關鍵字

繫帶水解物；酵素水解；酒精性肝損傷；抗氧化能力；脂質恆定

並列摘要

The chalaza of hen’s eggs is a kind of by-product from the liquid egg processing. To enhance the value of the hen’s egg chalaza, the two parts of objectives in this study were shown on the followings: (1). To manufacture a functional chalaza product by an enzymatic digestion; (2). To evaluate the hepatoprotection of this function products against chronic alcohol consumption. The crude chalaza was digested via three commercial proteases (pepsin, protease A, and prozyme 6). Via in vitro antioxidant evaluations and yield, the optimal condition for functional crude chalaza hydrolysates can be obtained by a protease A digestion (CCH-A) under a ratio of enzyme and substrate 1:100 (w/w) for 0.5 h. CCH-A was rich of Leu, Arg, Phe, Val, Lys, and taurine, as well as biodipeptides, i.e. anserine and carnosine, which are considered as antioxidant peptides. Next, 18 male C57BL/6 mice with 8-week old age were used in the experiment and divided randomly into CON (control liquid diet), ALC (ethanol liquid diet + normal saline), and ALC+CCH-A (ethanol liquid diet + 100mg CCH-A/kg BW) groups and the experiment last for 8 weeks. Decreased (p<0.05) liver antioxidant capacities, and increased liver lipid contents, serum liver damage indexes and proinflammatory cytokines (IL-1β and IL-6) were assayed in alcohol-fed mice than those in control ones. CCH-A supplementation reversed (p<0.05) liver antioxidant capacities. It also reduced (p<0.05) serum and hepatic lipids in alcohol-fed mice which may result from increased (p<0.05) fecal lipid outputs and gene expressions of fatty acid β-oxidation (Pparα, Lxr-α, Cpt1, and Ucp2) and downregulated (p<0.05) lipogenesis (Fas) in livers. In conclusion, the optimal condition for manufacturing functional CCH-A was decided and the hepatoprotection of CCH-A was also elucidated in this study. That this study not only benefits to the egg industry but also offers consumers another choice of healthy ingredients from eggs.