绿豆抗氧化活性肽的分离纯化及其组成分析

采用超滤法和Sephadex G-25凝胶色谱法对绿豆蛋白的酶解产物进行了分离纯化,得到了分子量为3426和1272u的两种绿豆抗氧化活性肽T1和T2,T1的纯度为85.92%,T2的纯度为94.99%,T1和T2均含有16种相同的氨基酸,表现出较强的体外抗氧化能力,T1对羟自由基和DPPH自由基的清除率分别为69.14%和58.62%;T2对羟自由基和DPPH自由基的清除率分别为91.70%和74.68%。      

薏米中多酚化合物的分离纯化及抗氧化活性分析

利用葡聚糖凝胶将薏米中两类多酚类物质进行分离纯化,从而得到6个不同的组分。采用Folin-Ciocalteu法测定该6个组分总酚含量,采用氧自由基吸收能力(oxygen radical absorbance capacity,ORAC)、过氧化氢自由基清除能力(peroxyl radical scavenging capacity,PSC)和细胞内抗氧化能力(cellular antioxidant activity assay,CAA)分析法测定所得6个组分抗氧化能力。在所得的6个组分中选择抗氧化活性最强的3个组分进行半制备,可制得4种薏米多酚纯化物,并测定其4种纯化物的抗氧化活性。结果发现,所分离的6个组分中,薏米中的多酚主要存在于组分2、组分3及组分5中,其总酚含量分别为(30.56±2.25)、(17.40±2.76)、(25.18±1.10)mg GAE/100 g薏米粉末,结合型酚类化合物占薏米总酚含量1/3以上。组分2、组分3及组分5薏米多酚的抗氧化能力较强。经过半制备液相得到的4种多酚纯化物质分别为N_1,N_5-双(对香豆酰)亚精胺、对香豆酸、阿魏酸及芦丁,其中N_1,N_5-双(对香豆酰)亚精胺为游离型多酚的主要物质,而阿魏酸为结合型多酚的主要物质,但在游离型多酚中也有少许存在。4种酚类化合物均具有强抗氧化活性,是薏米中多酚类物质发挥抗氧化作用的主要活性成分。     

黑果枸杞中一种花色苷类物质的分离纯化及抗氧化活性

以黑果枸杞为原料,利用ÄKTA Purifier蛋白纯化系统分离纯化得到1 种纯度97%以上的花色苷物质。通过质谱和核磁共振分析,鉴定该花色苷物质为矮牵牛素3-O-芸香糖（反式-香豆酰基）-5-O-葡萄糖苷（petunidin3-O-[rhamnopyranosyl-(trans-p-coumaroyl)]-5-O-(β-D-glucopyranoside)）。体外抗氧化活性分析表明该花色苷物质具有显著的1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基和超氧阴离子自由基（O2 － ·）清除能力。     

ANTIOXIDANT PROPERTIES OF LENTINUS EDODES AND AGARICUS BLAZEI EXTRACTS

ABSTRACT

This work aimed to evaluate the antioxidant activity of Lentinus edodes and Agaricus blazei mushrooms, as well as to measure the content of total phenolic compounds of mushroom extracts and verify the oxidative stability of soybean oil added with mushroom extracts that showed higher antioxidant activity according to the methods of the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^•) free radical scavenging and the β‐carotene/linoleic acid system. According to the DPPH^• method, the maximum antioxidant activity for L. edodes and A. blazei methanol extracts was 92.84 and 95.10%, respectively. For the β‐carotene/linoleic acid system, the highest values of antioxidant activity were 93.06% for L. edodes and 78.96% for A. blazei. The content of total phenolic compounds ranged from 7.21 to 128.44 and 26.67 to 134.67 mg gallic acid equivalent/g for L. edodes and A. blazei, respectively. The oxidative stability values provided by the Rancimat method indicated that the two varieties presented similar induction period of 19.85 h.

PRACTICAL APPLICATIONS

Mushrooms present high content of antioxidant compounds that are capable of reducing the harmful effects of free radicals. Among the antioxidants present in mushrooms, phenolic compounds stand out as phenolic acids, flavonoids and tocopherols. To decrease or prevent lipid oxidation, synthetic antioxidants are used as food additives. Nevertheless, studies have revealed that these compounds are likely to pose risks to human health. The concern regarding the safety of synthetic antioxidants has motivated the search of natural antioxidants that can substitute them totally or partially.

     

竹黄多糖BSP-1的组成和抗氧化活性分析

对竹黄子实体总多糖进行提取,分离纯化出2种均一的组分BSP-1和BSP-2.采用气相色谱和凝胶渗透色谱研究BSP-1的组成和分子量,并研究其对猪油的抗氧化作用.结果表明:BSP-1分子量为45.64 ku,主要由葡萄糖和甘露糖组成,摩尔比为2.46:1,红外光谱分析表明含有B-糖苷键,体外抗氧化实验证明BSP-1具有一定的抗猪油自动氧化能力.     

香菇谷氨酰胺转氨酶的酶学性质研究

采用超滤浓缩,乙醇沉淀,冷冻干燥和SephadexG-100层析等方法,获得香菇谷氨酰胺转氨酶粗酶及纯酶,对其酶学性质进行研究.结果表明:香菇中谷氨酰胺转氨酶粗酶的最适反应温度为40℃,温度稳定范围在50℃以下,最适PH为6.0,pH稳定范围在5.0～7.0,Na+、Ca2+等离子对该酶的活性影响甚微,为非Ca2+依赖性酶;纯酶的最适温度为40℃,以Nα-CBZ-Gin-Gly为底物时香菇谷氨酰胺转氨酶的Vmax为0.020mg/(mL·min),Km为1.520g/L.     

ANTIOXIDANT ACTIVITY OF WHEAT CARYOPSES AND EMBRYOS EXTRACTS

Phenolic compounds were extracted with 80% methanol from caryopses and embryos of wheat (cv. Alba and Elena). In extracts the content of total phenolics was determined and UV spectra recorded. For all extracts the antioxidant activity in a β-carotene-linoleate model system, scavenging effect on DPPH radical, and reducing power were examined. Extracts of wheat embryos were characterized by a higher content of total phenolics. UV spectra of phenolic compounds extracted from wheat caryopses were characterized by maxima close to 320 nm due to phenolic acids, and by maxima at shorter wavelengths (272–280 nm) attributed to other phenolic compounds. The antioxidant activities of extracts from caryopses in a β-carotene-linoleate model system were higher than those from embryos. The results so obtained were similar to those observed previously for extracts of rye and triticale grains and leguminous seeds. The scavenging effect of wheat extracts on DPPH radical and their reduction power were weak, but those for embryos extracts were somewhat stronger.     

ANTIOXIDANT ACTIVITY OF EXTRACTS OF PHENOLIC COMPOUNDS FROM RAPESEED OIL CAKES

Oil cakes were prepared from commercial rapeseeds of the double-low Bolko variety using a complete technological line. Samples of the oil cake containing 8.1, 9.9, 11.4, and 14.4% moisture were stored for 1, 2 and 3 months at 15C and a relative humidity of 78%. The content of total phenolics in the extracts so obtained did not depend on the moisture content of the oil cake or the length of storage; values ranged from 77 to 81 mg/g. In the extract obtained from nonpressed rapeseeds, a similar content of total phenolics (80 mg/g) was determined. UV spectra of the extracts studied were characterized by maximum absorbance at 330 nm. This wavelength indicates that sinapine was the main phenolic compound in the extracts. However, the extract obtained from the cake with the lowest moisture content and stored for 3 months exhibited a maximum absorbance at 328 nm. All the extracts showed good antioxidant activity, as assessed using a β-carotenelinoleate model system. Antioxidative properties of extracts obtained from rapeseed cakes were similar to those of extracts from nonpressed seeds.