夏枯草酸性多糖的理化性质分析及其抗氧化活性

水提醇沉后的夏枯草粗多糖用HZ-820大孔吸附树脂脱色素和蛋白质,再经DEAE-Sepharose Fast Flow离子交换柱色谱和Sephadex G-50凝胶柱色谱进一步纯化得到高纯度酸性多糖,用气相色谱、高效凝胶渗透色谱、红外光谱、热稳定性分析、扫描电镜等对其理化性质进行了分析,最后研究了其抗氧化活性。结果表明,夏枯草酸性多糖中含有鼠李糖、木糖、阿拉伯糖、葡萄糖和甘露糖,其质量分数分别为0.985 7%、1.756 8%、3.202 9%、1.975 3%、0.680 6%,重均相对分子质量为57 234。夏枯草酸性多糖在230℃开始发生降解,600℃基本结束,说明其具有较好的热稳定性。夏枯草酸性多糖表面基本光滑,呈薄片状且无规则蜷曲。抗氧化研究表明,夏枯草酸性多糖能够有效地清除NO2-自由基,同时具有较强的还原能力和对铁离子的螯合能力。     

Quantification of (+)-catechin and (−)-epicatechin in coconut water by LC–MS

An analytical technique has been developed to detect trace amounts of both (+)-catechin and (−)-epicatechin in the coconut water extract. Both (+)-catechin and (−)-epicatechin in the coconut water were found for the first time by the solid-phase extraction, and they were further analysed using liquid chromatography (LC)–ion trap mass spectrometry (MS) equipped with positive atmospheric pressure chemical ionisation interface on multiple reaction monitoring mode. The limit of detection and quantification for (+)-catechin were 7.8 and 15.6 μg/ml, respectively, while those for (−)-epicatechin were 3.9 and 7.8 μg/ml, respectively. The average concentration of (+)-catechin and (−)-epicatechin in the coconut water was 0.344 and 0.242 μg/ml, respectively. The LC–MS/MS analysis accelerated the quantitative analysis of (+)-catechin and (−)-epicatechin in the coconut water extract with high accuracy, precision and recovery. Results obtained in this study will serve as quality control and useful reference for drug development.     

Antibacterial and antioxidant activities of the essential oil and methanol extracts of Bidens frondosa Linn

Antibacterial and antioxidant potential of essential oil, extract and its fractions of Bidens frondosa Linn were evaluated. Sixty‐one components representing 95.41% of the total oil were identified. The essential oil (7.5 μL disc^?1), methanol extract and its different organic subfractions (0.5 μg disc^?1) of B. frondosa displayed a great potential of antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19116, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella enteritidis KCTC 12021 and Enterobacter aerogenes KCTC 2190. Antioxidant activity was evaluated by using 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. The free radical scavenging activity of ethyl acetate (EtOAc) fraction was superior to all other fractions (IC₅₀ = 11.96 μg mL^?1), which was higher than synthetic antioxidant butylated hydroxyanisole, (IC₅₀ = 18.27 μg mL^?1). Furthermore, the amount of total phenolic compounds was determined and its content in EtOAc fraction was the highest as compared to methanol extract or other fractions. The results indicate that the oil and extracts of B. frondosa could serve as an important bio‐resource of antimicrobial agents and antioxidants for using in the food industries.     

芒果叶多糖的提取及含量测定

为生产各种食用品、化妆品、医药药品等多糖新产品提供重要原料,研究芒果叶多糖的提取条件和含量的测定。采用水提醇析的方法提取了芒果叶中多糖,采用硫酸-苯酚法进行了糖含量测定。结果显示,多糖在484 nm有最大吸收峰,求得其回归方程为A=0.126 9C-2.076 27×10-3,相关系数r=0.999 5;平均回收率为96.14%,RSD=1.094%(n=5)。芒果叶中多糖含量为1.516%。     

The effect of acid and glucoamylase hydrolysis on partial physicochemical properties and characteristics of Dioscorea alata Linn. starch

Dioscorea alata Linn. (D. AL) rich in starch was widely used as food and medicine. This work aimed to compare the effect of acid and glucoamylase on the starch of different reaction time. The physicochemical properties of the native and hydrolyzed starches, such as swelling power (SP), starch solubility (SOL), and paste clarity were also determined in this study. The native and modified starches by acid and glucoamylase were compared and characterized by scanning electron microscope (SEM) and secondary derivative FT‐IR spectroscopy. The morphological characteristics of native D. AL starch granules revealed by SEM varied from round to oval or elliptic with smooth surface. SEM showed that glucoamylase primarily attacked the exterior of starch granules and permeate into the interior by the cracks formed on the surface. Owing to acid hydrolysis, the starch granules were depressed and transformed to bread‐like in shape and then broke into irregular lumps with particles adhered. From secondary derivative FT‐IR spectrum, the intensities of the two peaks from acid and enzyme hydrolysis starches at 1137 and 1066/cm were stronger than native starch. Some new peaks appeared due to hydrolysis. The digested starches exhibited a lower SOL and SP than native starch in water as the temperature increasing. The light transmittance of the digested starches was significantly higher than that of native starch paste and decreased with increase in storage period.     

一点红提取物体外抗氧化活性研究

目的:研究一点红提取物体外抗氧化活性。方法:通过水提醇沉、有机溶剂萃取、大孔树脂吸附纯化,得到六种不同部位的样品。以抗坏血酸和2,6-二叔丁基-4-甲基苯酚为对照,测定样品对羟基自由基和二苯基苦基苯肼自由基的清除能力,对Fe3+的还原能力,抑制油脂的氧化能力。结论:上述样品均具有一定的抗氧化活性,其中大孔树脂纯化的50%乙醇洗脱部位活性最好,但总体上弱于抗坏血酸和2,6-二叔丁基-4-甲基苯酚。     

In vitro anti‐HSV‐2 activity and mechanism of action of proanthocyanidin A‐1 from Vaccinium vitis‐idaea

The aim of this study was to investigate the in vitro anti‐HSV‐2 activity and mechanism of action of proanthocyanidin A‐1, a compound isolated from Vaccinium vitis‐idaea Linn (Ericaceae). The results demonstrated that proanthocyanidin A‐1 exhibited anti‐HSV‐2 activity. The IC₅₀ value for the XTT assay was 73.3 ± 14.5 µM and the IC₅₀ and IC₉₀ values for the plaque reduction assay were 41.9 ± 2.0 and 62.8 ± 6.3 µM respectively. Proanthocyanidin A‐1 showed no cell cytotoxic effect at concentrations that blocked HSV‐2 infection, with a CC₅₀ value of 282.1 ± 27.5 µM . The mechanism studies demonstrated that proanthocyanidin A‐1 did not reduce viral infectivity but inhibited viral attachment and penetration and affected the late stage(s) of HSV‐2 infection. It was concluded that proanthocyanidin A‐1 suppressed HSV‐2 infection through many modes of action and thus merits further investigation. Copyright © 2004 Society of Chemical Industry     

黄瓜黄酮类化合物的抗氧化作用

以70%乙醇为溶剂提取黄瓜黄酮类化合物,并对其黄酮含量进行测定;采用水杨酸比色法测定黄瓜中黄酮类化合物对羟基自由基的清除效果.结果表明:黄瓜中含有黄酮类化合物;且黄瓜中黄酮类化合物对羟基自由基有明显的清除效果,清除率达63.95%.     

多巴胺-沙棘枝条粉/聚丙烯酸复合材料的制备及性能研究

以附有多巴胺的废弃沙棘枝条粉(PD-HBP)和丙烯酸(AA)为原料,过硫酸钾(K2S2O8)为引发剂,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,制备了环境友好型PD-HBP/PAA(聚丙烯酸)高吸水性复合材料。采用红外光谱(FTIR)和场发射电子扫描电镜(FE-SEM)表征产物的结构。考察了盐溶液浓度、离子类型及反复使用次数对PD-HBP/PAA吸水能力的影响。结果表明,PD-HBP/PAA在去离子水、自来水和0.9%(质量分数)NaCl溶液的吸水倍率分别可达251.7g/g、172.0g/g和42.1g/g,吸水性能对盐溶液浓度、离子类型及洗水次数较为敏感。反复吸放液7次后,去离子水和0.9%(质量分数)NaCl溶液的吸水倍率分别保持了最大吸水倍率的73.3%和53.0%。     

樟树果红色素在不同环境条件下稳定性的研究

研究了樟树果红色素在不同环境条件下的稳定性,结果表明,该色素耐热性和耐光性较好,粗提物比纯提物的耐热性要高得多,色素是否纯化对色素光稳定性影响不显著。