维生素C缩醛衍生物的合成及清除自由基性能研究

以对甲苯磺酸为催化剂,N,N-二甲基乙酰胺为溶剂,环己烷为带水剂,维生素C与醛为原料,合成了7种维生素C缩醛衍生物,并且对其进行了熔点、红外光谱、核磁共振氢谱表征。通过分光光度法研究了目标化合物清除超氧阴离子自由基和DPPH自由基的性能。结果表明,维生素C缩醛衍生物均具有出色的清除自由基的能力,而且当受试物的物质的量浓度相同时,维生素C缩醛衍生物清除超氧阴离子自由基和DPPH自由基的能力与维生素C相当,略高于TBHQ。

肉桂酸Vc酯和肉桂酸异Vc酯的合成及其性能研究

肉桂酰氯分别与Vc(L-抗坏血酸)和异Vc(D-异抗坏血酸)反应,得到肉桂酸Vc酯1和肉桂酸异Vc酯2,1和2的结构经IR、1H NMR、13C NMR和EI-MS确证。用分光光度法测试了产物清除DPPH自由基、羟基自由基和超氧阴离子自由基性能,用孔穴扩散法测试了产物对金黄葡萄球菌、大肠杆菌、枯草芽孢杆菌和细黄链霉菌的抗菌性能。结果表明,当受试物的摩尔浓度相同时,产物1和2清除上述三种自由基的能力分别比Vc和异Vc略有提高;当给药量为2 mg·mL-1时,产物1和2对上述四种菌种的抑菌效果与肉桂酸、山梨酸钾和苯甲酸钠大致相当。

大孔树脂对鱼腥草总黄酮的吸附分离及其抗氧化作用研究

采用静态吸附和解吸方法考察AB-8、H-103、X-5、NKA-9、S-8等五种大孔吸附树脂对鱼腥草总黄酮的吸附分离特性,并采用磷钼酸盐体系、DPPH自由基体系、邻苯三酚自氧化体系、邻菲萝啉体系以分光光度法测定鱼腥草总黄酮抗氧化及清除自由基作用。结果表明,AB-8树脂对鱼腥草总黄酮的吸附分离效果最佳,其静态吸附容量为56.27 mg/g,最佳解吸溶剂为70%乙醇,解吸率为96.45%,产物中总黄酮纯度为60.98%,为纯化前的4.06倍。经纯化后的鱼腥草总黄酮表现出较强的抗氧化性能和自由基清除能力,其总抗氧化性能强于BHT,清除DPPH、超氧阴离子、羟基自由基的SC50值分别为12.0μg/mL、14.4μg/mL、12.8μg/mL。

大孔树脂对草珊瑚总黄酮的吸附分离及其体外抗氧化作用

采用静态吸附和解吸方法考察了AB-8、H-103、X-5、NKA-9、S-8等5种大孔吸附树脂对草珊瑚总黄酮的吸附分离特性,并采用磷钼酸盐体系、DPPH自由基体系、邻苯三酚自氧化体系、邻菲萝啉体系,以分光光度法测定草珊瑚总黄酮的抗氧化及清除自由基作用。结果表明,X-5树脂对草珊瑚总黄酮的吸附分离效果最佳,最佳解吸溶剂为70%乙醇,其静态吸附容量为62.43 mg/g、解吸率为92.5%,产物中总黄酮纯度为74.22%,为粗提物的2.14倍;经纯化后的草珊瑚总黄酮表现出中等强度的总抗氧化性能和较强的自由基清除能力,其清除DPPH、超氧阴离子、羟基自由基的SC50值分别为16.1、6.9和12.0μg/mL。

酸浆宿萼多酚类物质提取工艺研究及抗氧化活性评价

以多酚提取量为指标,采用单因素试验,确定酸浆宿萼多酚类物质的提取工艺。通过多酚对羟自由基(·OH)、1,1-二苯基-2-三硝基苯肼自由基(DPPH·)和2,2'-二氮-双(3-乙基苯并噻唑-6-磺酸)自由基(ABTS·)的清除作用来评价抗氧化活性。结果表明:酸浆宿萼多酚类物质的提取工艺为提取次数2次、浸提溶剂乙醇、乙醇体积分数70%、液料比20∶1(g/m L)、提取温度75℃、浸提时间20 min。该多酚类成分具有一定的抗氧化能力,当多酚质量浓度为1 mg/m L时,对羟自由基和DPPH自由基以及ABTS自由基的清除率分别为24.45%、50.27%和95.31%。由此可知,酸浆宿萼多酚类物质具有很强的抗氧化能力,可用于制备天然抗氧化剂。

Purification and characterization of novel antioxidant peptides of different molecular weights from mackerel Pneumatophorus japonicus protein hydrolysate

Mackerel （Pneumatophorus japonicus） proteins were hydrolyzed by five proteases： trypsin, papain, neutrase, acid protease, and flavourzyme. The hydrolysate treated by neutrase exhibited the highest antioxidant activity. Response surface methodology （RSM） was employed to optimize the hydrolysis conditions in an effort to obtain a mackerel protein hydrolysate （MPH） with the highest DPPH radical scavenging activity. The MPH was fractioned using a series of ultrafiltration membranes and five fractions, namely, MPH-I （〉10 kDa）, MPH-II （10-2.5 kDa）, MPH-III （1-2.5 kDa）, MPH-IV （0.4-1 kDa）, and MPH-V （below 0.4 kDa）, were obtained. DPPH radical scavenging activity, reducing power, hydroxyl radical scavenging activity, and the lipid peroxidation inhibition capability of these fractions were evaluated. The fractions in molecular weights 〈2.5 kDa （MPH-III, MPH-IV, and MPH-V）, which occupied 93.4% of the total fractions, showed the strongest antioxidant activity; and the antioxidant activities of the three fractions are similar to each other. Using SP Sephadex C-25 and Sephadex G-25 columns, eight fractions were obtained from the MPH （〈2.5 kDa）. The isolated peptide I （1 664 kDa） displayed the highest DPPH radical scavenging activity. Therefore, MPH is a potential source of antioxidant peptides.

The Scavenging of Free Radical and Oxygen Species Activities and Hydration Capacity of Collagen Hydrolysates from Walleye Pollock(Theragra chalcogramma) Skin

Fish skin collagen hydrolysates （FSCH） were prepared from walleye pollock （Theragra chalcogramrna） using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of 〈1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical （DPPH）, superoxide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione （GSH）. FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scavenge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore FSCH may have potential applications in the medicine and food industries.

Study on the Molecular Weight Composition and Antioxidant Activity of Peanut Bioactive Peptides

[ Objective] To prepare peanut bioactive peptides and analyze their molecular weight composition and antioxidant activity. [ Method ] The dialysis bag of 8.0, 3.5 and 1.0 kD were used to classify the hydrolyzate derived from alcalase and flavourzyme, peanut bioactive poptides of differ-ent molecular weight were obtained and then their scavenging capacity of free radicals was measured. The molecular weight composition was stud-ied by Tricine-SDS-PAGE.[Result] The content of peptides 〈 1.0 kD were 76.21% and 83.42% in the total hydrolyzate from alcalase and fla-vourzyme respectively. All hydrolyzate with different molecular grades showed free radical scavenging capacity, which was increased with the reduc- tion of molecular mass. The peptides 〈 1.0 kD exhibited higher radical scavenging capacity of （87.41 ±0.66） % （alcalase） and （67.88 ±0.48）% （ flavourzyme）, respectively. [ Conclusion] Peanut bioactive peptides had strong effect of antioxidant capacity, especially that 〈 1.0 kD, which had great prospect.