超声辅助酶法制备海参性腺多糖的结构特性及抗氧化活性

以海参性腺为原料，采用超声辅助酶（ultrasound-assisted enzymatic，UAE）法制备海参性腺粗多糖，后经分离纯化得到海参性腺多糖（sea cucumber gonadal polysaccharide，SCGP）-UAE，探究其结构特性和抗氧化活性，并与酶法和超声法制备的SCGP-E和SCGP-U进行比较。结果表明，SCGP-UAE的总糖质量分数（69.13%）显著高于SCGP-E（58.76%）和SCGP-U（62.93%）（P＜0.05）。3 种SCGP的紫外光谱及傅里叶变换红外光谱具有相似的特征峰。刚果红实验、扫描电子显微镜及热稳定性测定结果显示，3 种SCGP均不含三股螺旋结构，表观呈现片状结构，具有较好的热稳定性。当多糖质量浓度为4 mg/mL时，SCGP-UAE的2,2’-联氮-双-3-乙基苯并噻唑啉-6-磺酸阳离子自由基、超氧阴离子自由基清除率和亚铁离子螯合能力较SCGP-U分别高5.59%、14.05%和26.63%，较SCGP-E分别高2.16%、33.59%和47.10%。综上所述，UAE法提取率高，所制备多糖的抗氧化活性较好，表明UAE法是一种较好的SCGP制备方法。

Structural Characteristics and Antioxidant Activity of Polysaccharides Prepared from Sea Cucumber Gonad by Ultrasound-Assisted Enzymatic Hydrolysis

The structural characteristics and antioxidant activity of sea cucumber gonadal polysaccharide (SCGP) by ultrasound-assisted enzymatic hydrolysis (named SCGP-UAE) were evaluated in comparison with those prepared by enzyme-assisted extraction (named SCGP-E) and ultrasound-assisted extraction (named SCGP-U). The results showed that the total sugar content of the SCGP-UAE sample (69.13%) was significantly higher than that of the SCGP-E sample (58.76%) and the SCGP-U sample (62.93%) (P < 0.05). The ultraviolet and Fourier transform infrared (FTIR) spectra of the three polysaccharides showed similar characteristic absorption peaks. The results of Congo red experiment, scanning electron microscopy and thermal stability measurement showed that none of the polysaccharide samples contained a three-stranded helix structure, despite all showing an apparent lamellar structure and having good thermal stability. At 4 mg/mL concentration, the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical and superoxide anion radical-scavenging activity and Fe2+-chelating ability of SCGP-UAE were 5.59%, 14.05% and 26.63% higher than those of SCGP-U, and 2.16%, 33.59% and 47.10% higher than those of SCGP-E, respectively. In summary, the ultrasound-assisted enzymatic hydrolysis method could extract polysaccharides with good antioxidant activity from sea cucumber gonad in high yield and thus have great application potential.