農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

魷魚皮為加工過程中所產生之副產物，僅利用作為飼料或肥料使用，不具經濟價值。為提升魷魚皮之應用性，將魷魚皮以酵素水解所製備之水解物，經由人工胃腸液之體外消化試驗顯示，分子量＞3000 Da 之區間有顯著地減少並伴隨顯著增加於分子量＜700 Da 之區間；另經腸胃道消化後之胜肽其抗氧化活性相較於未處理組，在 DPPH 清除能力、螯合亞鐵能力、還原力及 SOD 等分別顯著增加為 91.3±0.4%、97.7±0.3%、2.6±0.1 (abs) 和 74.2±0.2%。此外消化後對血管升壓素轉換酶 (ACE) 活性之抑制率 (IC50) 為 83 (μg peptide/mL) 與未處理組 (65 μg peptide /mL) 經統計分析無差異，此等結果顯示魷魚皮酵素水解物口服消化後仍具有抗氧化與調節血壓之能力。另將 Bacillus subtilis FRI1 和FRI3 混合接種於含有魷魚皮之培養基中，在 150 rpm 下於 37℃ 發酵 72 hr 可產生較高活性之血栓分解酶。在延緩老化之細胞試驗結果顯示，胜肽 (0.1~5 mg/mL) 經 MTT 試驗證實對神經細胞 (neuroblastoma cell; SHSY5Y) 無毒性。在濃魷魚皮之蛋白水解度為 1.2~2.5 mg/mL 時可活化神經細胞且顯著促進過氧化氫酶 (catalase)、超氧歧化酶 (superoxidedismutase; SOD) 和穀胱甘肽過氧化酶 (glutathione peroxidase (GSH-Px) 等抗氧化酵素之活性。此外 400 uM 過氧化氫 (H2O2) 可誘導神經細胞使其 ROS 產生量顯著提升 5.6 倍，進而對細胞產生氧化損傷，並使神經細胞之存活率顯著降低至 65.7%。然而魷魚皮酵素水解物 (1.2 mg/mL) 可顯著提升細胞內抗氧化酵素表現量的，以清除自由基進而防止 H2O2 對神經細胞所造成的氧化損傷，而提升神經細胞的存活率。
綜合上述結果顯示，魷魚皮之水解物或其納豆菌之發酵物具有良好的抗氧化、血壓調節、血栓清除與延緩老化的能力，可應用做為機能保健食品或營養補充品之海洋性新素材的發展潛力，達到活用低度利用水產資源之目的。

Squid skins are byproducts during the fish processing, generally used as low-value feedstuffs or fertilizers. In order to increase the utilization of squid skin, we prepared hydrolysates from squid skin by commercial protease, and then to evaluate the functional properties. Results showed that the changes of molecular weight distribution of the enzymatic hydrolysates from squid skin after treated with gastrointestinal protease, significant decreasing the peptides with molecular weight more than 3000 Da, whereas significant increasing those less than 700Da. And the antioxidant abilities including DPPH free radical scavenging activity, chelating activity of Fe2+, reducing power, and SOD activity of peptides, released from gastrointestinal digestion, were 91.3±0.4%, 97.7±0.3%, 2.6±0.1 (abs), and 74.2±0.2%, respectively. These values of antioxidant activities were significantly increased as compared to untreated group in the vitro gastrointestinal digestion. In addition, no significantly difference was observed in the IC50. Values of angiotensin I-converting (ACE) inhibitory activity of peptides, which before (65 μg peptide /mL) and after (83 μg peptide/mL) treatment with gastrointestinal protease in vitro digestion. These results indicated the hydrolysates from squid skin exhibited antioxidative activities and blood pressure regulation after oral administration. Furthermore the highest fibrinolytic enzyme activity from squid skin fermented with Bacillus subtilis FRI1 and FRI3 was observed under 150 rpm at 37℃ after 72hr administration. Enzymatic hydrolysates from squid skin was demonstrated no cytotoxicity to neuroblastoma cells (SH-SY5Y) by MTT assays. Moreover, the hydrolysates (0.1-5 mg/mL) can dose-dependently stimulate the neural cell proliferation and significantly promote the activities of catalase, superoxide dismutase (SOD) and glutathione peroxide (GSH-Px) on the SH-SY5Y cells at the concentration of 1.2~2.5mg/mL. Hydrogen peroxide (H2O2) is prooxidant, that induced SH-SY5Y cells to produce approximately 5.6 times of reactive oxygen species (ROS) as well as the survival rate of cells decreased significantly to 65.7% as compared to control (without H2O2) under oxidative stress. However, hydrolysates of squid skin (1.2 mg/mL) could increase significantly the expression of antioxidant enzymes in SH-SY5Y cells, and consequently scavenge free radicals, thus increase survival rate of the neural cells and against H2O2-induced oxidative damage. In summary, hydrolysates of squid skin by enzymatic hydrolysis or Bacillus fermentation could be used as a novel candidate for antioxidant, blood pressure regulatory, fibrinolytic agents and anti-aging on the functional food or supplementary. Therefore, optimized utilization of this under-utilized squid skin, especially the production of value-added products, is a promising means to increase the revenue of producers.
Key words: Squid skin, Free radical scavenging activity, Fibrinolytic enzyme, Angiotensin I-converting (ACE) enzyme, Anti-aging