采用复合蛋白酶对沙虫(Sipunculus nudu)进行酶解，得到沙虫蛋白酶解产物(SNPH)，并对其氨基酸组成进行了分析。采用高效液相凝胶色谱法对SNPH的相对分子质量分布进行了测定。采用紫外分光光度法测定SNPH对DPPH自由基，羟基自由基、超氧阴离子的清除能力及其还原能力。采用四甲基偶氮唑盐(MTT)法检测SNPH在对刀豆蛋白(Con A)和脂多糖(LPS)诱导的小鼠脾淋巴细胞增殖作用的影响。结果显示SNPH中必需氨基酸和疏水氨基酸含量较高，小分子肽含量较高，相对分子质量在120~1800之间的物质占85.11%。抗氧化活性实验显示SNPH对DPPH自由基，羟基自由基和超氧阴离子具有较强的清除效果，且清除率与浓度存在一定的量效关系。免疫调节活性试验表明SNPH对Con A和LPS诱导的小鼠脾淋巴细胞的增殖具有协同刺激作用。SNPH具有较好的抗氧化和免疫调节活性。

Enzymatic hydrolysis of Sipunculus nudus was performed using Protamex to obtain SNPH. Subsequently, the amino acid composition of SNPH was analyzed, and the distribution of relative molecular mass was determined using a high performance gel chromatography method. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, hydroxyl radical scavenging activity, superoxide anion scavenging activity, and reducing power of SNPH were evaluated using ultraviolet (UV) spectrophotometry. The effects of SNPG treatment on the splenic lymphocyte proliferation induced by concanavalin (Con) A and lipopolysaccharide (LPS) in mice were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results indicated that SNPH had high contents of essential amino acids and hydrophobic amino acids. The molecular weight distribution showed that SNPH had a high content of oligopeptides, and the substances with a relative molecular mass of 120~1800 accounted for 85.11%. The antioxidant activity experiment revealed that SNPH possessed potent scavenging activities on DPPH free radical, hydroxyl free radical, and superoxide anion in a good dose-effect relationship. The experiment on immunomodulatory activity indicated that SNPH could have a synergistic effect on the splenic lymphocyte proliferation induced by Con A and LPS. SNPH had good antioxidant and immunomodulatory activities.

广西壮族自治区海洋生物技术重点实验室开放课题（GLMBT-201407）；广西中药质量标准研究重点实验室自主研究课题（桂中重系201501）；国家自然科学基金资助项目（41306133）；上海市奉贤区科委重点项目（20141001）