Guo Xin, Chen Shiguo, Hu Yaqin, Li Guoyun, Liao Ningbo, Ye Xingqian, Liu Donghong, Xue Changhu
College of Biosystem Engineering and Food Science, Zhejiang University, Hangzhou, 310029 China.
College of Food Science and Technology, Ocean University of China, Qingdao, 266003 China.
J Food Sci Technol. 2014 Dec;51(12):3680-90. doi: 10.1007/s13197-013-0937-7. Epub 2013 Feb 5.
Water-soluble squid melanin fractions were firstly prepared using ultrasound-assistant degradation method under alkaline condition, which is optimized by response surface methodology. The processing melanin fractions were divided into different molecular weight (Mw) fractions by membrane separation (below 10 kDa, among 10-50 kDa and over 50 kDa). The AFM image and particle-size analysis showed monomer units of the melanin were destroyed, and huge polymers were degraded into smaller soluble particles after ultrasound. While, UV, IR and solid (13)C NMR spectra indicated that the basic structure of melanin fraction was still retained after ultrasound process. Further analysis showed soluble melanin fractions obtained in 0.5 and 1 M NaOH, with Mw above 10 kDa exhibited much higher in vitro antioxidant potency. The IC50 of these fractions (IC50 among 19-80 μg) on scavenging O 2 ∙¯ is more efficient than carnosine (IC50 = 355 μg/ml.), a commercialized antioxidant. They (IC50 mong 115-180 μg/ml) are as efficient as carnosine (IC50 = 110 μg/ml) on scavenging ∙OH. Our research has reported a novel method for preparation of water-soluble melanin fractions from squid ink, which could be a promising free radical scavenger from nature resource.
首先在碱性条件下采用超声辅助降解法制备水溶性鱿鱼黑色素级分，并通过响应面法对其进行优化。将处理后的黑色素级分通过膜分离分为不同分子量（Mw）的级分（低于10 kDa、10 - 50 kDa之间和高于50 kDa）。原子力显微镜（AFM）图像和粒度分析表明，黑色素的单体单元被破坏，超声处理后巨大的聚合物降解为较小的可溶性颗粒。同时，紫外（UV）、红外（IR）和固体碳-13核磁共振（(13)C NMR）光谱表明，超声处理后黑色素级分的基本结构仍然保留。进一步分析表明，在0.5和1 M NaOH中获得的Mw高于10 kDa的可溶性黑色素级分表现出更高的体外抗氧化能力。这些级分对超氧阴离子（O₂∙¯）清除的半数抑制浓度（IC50在19 - 80 μg之间）比商业化抗氧化剂肌肽（IC50 = 355 μg/ml）更有效。它们（IC50在115 - 180 μg/ml之间）对羟基自由基（∙OH）的清除效果与肌肽（IC50 = 110 μg/ml）相当。我们的研究报道了一种从鱿鱼墨汁中制备水溶性黑色素级分的新方法，其可能成为一种有前景的天然自由基清除剂。
