运用紫外分光光度法，首次对北部湾优势种海鞘皱瘤海鞘Styela plicata各有机相的总还原力、DPPH自由基、O2-·和·OH的清除能力进行测试，总还原力实验中乙酸乙酯相和水相在100 μg/mL时的吸光度分别为0.149和0.122。DPPH·清除能力较好的是水相，其IC50为6.10 μg/mL。水相和乙酸乙酯相对O2-·的IC50分别为10.26 μg/mL和2.18 μg/mL，两者对·OH的IC50分别为2.30 μg/mL和9.65 μg/mL。表明皱瘤海鞘次级代谢产物中的体外抗氧化活性组分主要集中于水相浸膏和乙酸乙酯相。运用正反相硅胶柱层析、Sephadex-LH20凝胶柱层析法和半制备HPLC对乙酸乙酯相进行分离纯化，运用NMR、MS波谱学方法结合理化性质和TLC技术纯化鉴定了其中3个多羟基甾体类化合物的结构为cholestane-1,3,5,6-tetraol(1)，(5)-cholestane-3,5,6-triol(2)和suberoretisteroids D(3)，这三个化合物均为首次从皱瘤海鞘中分离获得。实验结果为扩展皱瘤海鞘应用价值提供基础资料和指导，也为食源性的天然抗氧化剂的开发提供资源。

The total antioxidative activity, and the scavenging abilities of DPPH, superoxide and hydroxyl free radicals of the different organic extracts from the dominant squirt Styela plicata of Beibu Gulf were evaluated for the first time by ultraviolet spectrophotometry. In the total reducing power experiments, the absorbance values of the ethyl acetate phase and water phase at the concentration of 100 μg/mL were 0.149 and 0.122, respectively. The DPPH· scavenging ability is greater in the water phase, with the IC50 value being 6.10 μg/mL. The IC50 values of the water phase and ethyl acetate phase for superoxide anion were 10.26 μg/mL and 2.18 μg/mL, respectively, with their corresponding IC50 values for hydroxyl free radical were 2.30 μg/mL and 9.65 μg/mL, respectively. The results showed that the active components of the squirt’s secondary metabolites possessing significant in vitro antioxidant activity were mainly concentrated in the aqueous phase and ethyl acetate phase. The ethyl acetate phase was subjected to further separation and purification by normal- and reversed-phase silica gel column chromatography, Sephadex LH-20 column chromatography and semi-preparative HPLC. The structures of active compounds were characterized by spectroscopic methods including NMR and MS, and three of which were identified as polyhydroxy sterols cholestane-1,3,5,6-tetraol(1), (5)-cholestane-3,5,6-triol(2) and suberoretisteroids D(3). These three compounds were obtained from S. plicata for the first time. The experimental results provide fundamental information and guidance for increasing the application value of S. plicata and also offers resources for the development of food-derived natural antioxidants.

广西自然科学基金项目(2016GXNSFBA380011)；广西中医药大学2017年引进博士科研启动基金(B170033)；广西高校人文社科重点研究基地项目(0501801728)