Structural characteristics,fluorescence quenching,and antioxidant activity of the arabinogalactan protein-rich fraction from senna (<Emphasis Type="Italic">Cassia angustifolia</Emphasis>) leaves

Senna (Cassia angustifolia) is widely used in Indian folk medicine for the prevention of various disorders. Herein, we have demonstrated that water extracted arabinogalactan protein (AGP) rich fraction possesses strong antioxidative activity. The AGP rich fraction was analyzed using chemical, chromatographic, and spectroscopic methods. Effect of water extracted polymers on bovine serum albumin spectrum was determined using excitation wavelength of 282 nm. The antioxidant capacity of this fraction was studied by ferric reducing antioxidant power (FRAP) and DPPH radical assays. This polymeric fraction, ≥88% of which gets precipitated with Yariv reagent, consisted mainly of (1→5)-/(1→3,5)-linked α-arabinosyl, (1→3)-/(1→3,6)-linked-galactosyl residues and terminal arabinofuranosyl residues. Its in vitro antioxidant capacity is comparable to that of standard antioxidants. Fluorescence quenching studies furnishes evidence for the interaction of the arabinogalactan protein with bovine serum albumin.     

Sorption of pyrene to dissolved humic substances and related model polymers. 2. Solid-phase microextraction (SPME) and fluorescence quenching technique (FHT) as analytical methods

Sorption coefficients for pyrene on dissolved humic substances and on poly(acrylic acid) esters as well-defined model polymers were determined using solid-phase microextraction (SPME) and the fluorescence quenching technique (FQT). The results of both analytical methods were compared and theoretically evaluated, which led to the conclusion that the sorption coefficients measured by SPME and FQT are inevitably different: SPME measures activity-based and FQT concentration-based sorption coefficients. The environmental relevance of the two types of sorption coefficients is discussed. FQT is inappropriate to measure sorption coefficients for pyrene with the synthetic sorbents. Inspection of the vibrational structure of the fluorescence spectra of those solutions indicates a highly hydrophobic microenvironment of pyrene. This can be explained by an intra- or intermolecular agglomeration of hydrophobic moieties forming a favorable host for hydrophobic solutes.     

Structural features,antioxidant and tyrosinase inhibitory activities of proanthocyanidins in leaves of two tea cultivars

In this study the structural features, antioxidant, and tyrosinase inhibitory activities of proanthocyanidins in leaves of two tea cultivars, namely Huangjingui and Qilan, were investigated. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thiolysis-high performance liquid chromatography-electrospray ionization mass spectrometry analyses confirmed that these proanthocyanidins were built up a mixture of procyanidins, propelargonidins, and prodelphinidins, with the predominance of procyanidins. The proanthocyanidins in leaves of Huangjingui and Qilan cultivars exhibited potent antioxidant activities with IC₅₀ values of 87.36 ± 0.83 and 97.33 ± 0.61 µg/mL in 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay, 43.57 ± 0.25 and 55.01 ± 0.22 µg/mL in 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay, and with ferric reducing antioxidant power values of 4.83 ± 0.03 and 3.97 ± 0.02 mmol ascorbic acid equivalent/g in ferric reducing antioxidant power assay. It was also found that these proanthocyanidins had strong inhibition on tyrosinase activity with IC₅₀ values of 54.8 ± 1.27 and 20.0 ± 0.89 µg/mL for Huangjingui and Qilan cultivars, respectively. The results indicated that the proanthocyanidins in leaves of two tea cultivars could be considered as natural antioxidants and tyrosinase inhibitors applied in pharmaceutical and cosmetic industries in the future.     

龙竹竹叶多糖的提取及体外抗氧化研究

以水为溶剂对龙竹竹叶多糖(Polysaccharide from Dendrocalamus giganteus leaves,简称PDL)进行提取,优化了提取PDL的最佳工艺参数,通过响应面分析得出PDL提取工艺的最佳参数组合为:提取温度76.5℃、提取时间2.7h、料液比1:89。在此提取条件下,PDL提取量为4.41mg/g,精制后PDL纯度为63.18%。体外抗氧化研究表明:PDL对羟自由基、超氧阴离子有较强的清除作用,对DPPH的清除作用较弱;TBA试验表明PMBL抗脂质过氧化效果不够理想。     

Free radical scavenging, angiotensin I-converting enzyme (ACE) inhibitory, and in vitro anticancer activities of ramie (Boehmeria nivea) leaves extracts

The objectives of this study were to evaluate the antioxidant activity, angiotensin I-converting enzyme (ACE) inhibitory activity, and anticancer activity of ramie (Boehmeria nivea) leaves (RL). The RL was extracted with 70%(v/v) ethanol (RLE) and fractionated with the solvents of hexane, chloroform, ethylacetate, and aqueous. The ethylacetate fraction (EF) contained the highest phenolic contents of 651.65 mg/g, followed by RLE of 148.72 mg/g. The EF showed strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging with a 50% inhibition concentration (IC₅₀) of 0.097, 0.129, and 0.191 mg/mL, respectively. The ACE-inhibitory activity of EF was 80.32% at a concentration of 0.1 mg/mL. The EF showed growth-inhibitory effect of 67.21% at 0.25 mg/mL on the LoVo cell line, and 56.08% at 0.25 mg/mL on the NCI-H460 cell line, respectively. Therefore, it was suggested that the RL were potential materials for use as functional food and medicine.     

辣木叶多糖的分离纯化及其体外降糖活性研究

目的研究辣木叶多糖的制备、单糖组成以及体外降糖活性。方法采用水提醇沉、Sevage法、大孔树脂-阴阳离子交换树脂联用技术得到较高纯度辣木叶粗多糖,再进一步通过二乙氨基乙基纤维素和葡聚糖凝胶柱层析分离得到2个主要多糖组分(MOs-2-a、MOs-2-b),并通过水解衍生化对其单糖组成进行分析。此外,采用HepG2细胞建立胰岛素抵抗模型,以细胞葡萄糖消耗量为指标,考察辣木叶多糖的降糖作用。结果本文采用的制备工艺可以得到较高纯度的辣木叶粗多糖(纯度为73.10%),辣木叶多糖主要由甘露糖、鼠李糖、葡萄糖及半乳糖组成,其中各单糖摩尔比为0.49:3.65:0.63:1.27。与模型组相比,辣木叶多糖组分MOs-2-a、MOs-2-b均能显著增加胰岛素抵抗HepG2细胞的葡萄糖消耗量(P0.05)。结论辣木叶多糖MOs-2-a、MOs-2-b具有良好的降糖效果,本文可以为辣木叶多糖作为功能食品发展的提供科学依据。     

荷叶黄酮的分离及对油脂抗氧化的研究

本试验采用水提法提取荷叶黄酮,按提取温度80℃、料液比1∶20、提取时间为1.5 h条件得到荷叶黄酮提取量为17.33 mg/g。比较X–5、HP20、HPD100、HZ801、HZ818大孔吸附树脂对荷叶黄酮的静态吸附、洗脱性能,确定HPD100为适宜树脂。进一步考察大孔树脂HPD100的动态吸附洗脱能力,研究结果得出大孔树脂HPD100分离荷叶黄酮的适宜工艺参数为:常温下流速为2 BV/h,上样液浓度为0.700 mg/m L上柱吸附,洗脱流速为3 BV/h,体积分数60%乙醇洗脱,用量60 m L。在此工艺条件下,总黄酮得率为73.78%,总黄酮纯度为64.2%。对油脂抗氧化试验结果显示,添加量为1.50 mg荷叶黄酮抗氧化作用比2 mg维生素C好。     

Antioxidant and antibacterial activity of leaves of Etlingera species (Zingiberaceae) in Peninsular Malaysia

Methanolic extracts from fresh leaves of five Etlingera species were screened for total phenolic content (TPC), antioxidant activity (AOA), and antibacterial activity. Analysis of TPC was done using the Folin–Ciocalteu method. Evaluations of AOA included 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging ability, ferric-reducing antioxidant power (FRAP), ferrous-ion chelating (FIC) ability, and β-carotene bleaching (BCB) activity. Antibacterial activity was screened using the disc-diffusion method. Highest TPC, ascorbic acid equivalent antioxidant capacity (AEAC), and FRAP were found in leaves of E. elatior and E. rubrostriata. Leaves of E. maingayi, with the lowest TPC, AEAC, and FRAP, had the highest FIC ability and BCB activity. Ranking of TPC and AOA of different plant parts of E. elatior was in the order: leaves > inflorescences > rhizomes. Leaves of highland populations of Etlingera species displayed higher values of TPC and AEAC than those of lowland counterparts. Leaves of Etlingera species exhibited antibacterial activity against Gram-positive but not Gram-negative bacteria.     

灰毡毛忍冬茎叶不同极性成分的体外抗氧化活性研究

目的:探讨灰毡毛忍冬茎叶不同极性成分的体外抗氧化能力。方法:利用超声辅助萃取法分别得到了乙酸乙酯、正丁醇、甲醇和水提取物,采用1,1-二苯基-2-苦味偕腙肼自由基(DPPH.)法、Fe3+还原力测定实验和Folin-Ciocalteu法测总酚含量实验对各极性成分进行体外抗氧化活性评价,以Vc作阳性对照。结果表明,4种极性提取物对DPPH自由基均有较强的清除作用,其IC50值依次为14.51、6.97、8.80、11.95μg/mL;总酚含量分别达到了34.90、67.00、47.07、40.04mg/g;各提取物对铁离子的还原能力亦较强,与提取物浓度呈正相关性。结论:灰毡毛忍冬茎叶可作为天然抗氧化物质资源,具有潜在的开发利用价值。     

Antioxidant activity of dulse (Palmaria palmata) extract evaluated in vitro

Palmaria palmata (dulse) is traditionally consumed as a snack food and garnish; but, little is known about its potential as a source of antioxidants. A 1-butanol soluble fraction extracted from dulse exhibited OH scavenging activity ± EDTA (non-site and site specific activity) in a deoxyribose assay. EC₅₀ concentrations of dulse extract to quench DPPH and ABTS⁺ free radicals were 12.5 and 29.5 mg/ml. Dulse extract inhibited (p < 0.05) conjugated diene production in a linoleic acid emulsion at 24, 48 and 52 h, 38 °C; and inhibited (p = 0.044) thiobarbituric acid reactive substances (TBARS) production at 52 h. One milligram dulse extract exhibited reducing activity = 9.68 μg l-ascorbic acid and total polyphenol content = 10.3 μg gallic acid; the dulse extract did not chelate transition metal ions. The antioxidant activity of the dulse extract was associated with aqueous/alcohol-soluble compounds characterized by phenolic functional groups with reducing activity.     

Antithrombotic activity of fractions and components obtained from raspberry leaves (Rubus chingii)

The 70% ethanol fraction from an aqueous extract of raspberry leaves was shown to be the most antithrombotic fraction in in vitro and in vivo tests. The total flavonoids and phenolics in this fraction were 0.286 g/g and 0.518 g/g by colorimetry. Six compounds, including salicylic acid, kaempferol, quercetin, tiliroside, quercetin 3-O-β-d-glucopyranoside and kaempferol 3-O-β-d-glucopyranoside, were isolated from the active fraction. Among them, kaempferol, quercetin and tiliroside obviously delayed plasma recalcification time (PRT) in blood.     

In vitro study of the inhibitory effect of Fe(II), Fe(III) and Zn(II) ions on the activity of trypsin

The effect of Fe(II), Fe(III) and Zn(II) addition on the in vitro digestibility of casein was examined using trypsin as the proteolytic enzyme. The in vitro digestibility was determined by change in trichloroacetic acid (TCA) solubility of casein and by potentiometric titration. The effect of all three metal ions was also examined on the digestion of casein heated at 80°C for 15 min prior to the enzymic hydrolysis. Heat treatments did not cause significant changes in the proteolysis of casein. The addition of Fe(II) and Fe(III) clearly slowed the proteolysis in both heated and unheated casein. The decrease in rate of proteolysis was in a direct linear relationship with the amount of Fe(II) and Fe(III) addition. The inhibitory effect of Fe(III) was more pronounced as compared to Fe(II). The addition of Zn(II) did not affect the proteolytic activity in both heated and unheated casein.     

Improved flavonoid content in mulberry leaves by solid-state fermentation: Metabolic profile,activity, and mechanism

This study was aimed at investigating the mechanisms of release and transformation of total flavonoids (TFs) from mulberry leaves (MLs) by solid-state fermentation (SSF) via Aspergillus cristatus. An intelligent model based on a back-propagation artificial neural network (BP–ANN) was established to predict the TFs in fungi co-fermented MLs. After prediction and experimental validation, the TFs released by SSF (72.55 mg rutin equivalents/g dry weight) were significantly higher than that of unfermented (24.42 mg rutin equivalents/g dry weight). In addition, the biotransformation mechanism of flavonoids during SSF was proposed by analyzing the untargeted metabolome, including the flavonoid and phenylpropanoid biosynthetic pathways. Pearson's correlation coefficient analysis indicated that the 29 up-regulated catabolites (especially loureirin D and arachidoside) after SSF contributed to increased ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging activities and α-glucosidase inhibitory activities. Furthermore, structural characteristics (by scanning electron microscopy, thermogravimetric analysis, and FTIR spectroscopy) and analyses of dynamic changes in carbohydrate-hydrolyzing enzymes revealed that the destruction of hemicellulose was essential to releasing TFs by SFF.Industrial relevanceIn this study, a back-propagation artificial neural network (BP–ANN) was successfully used to establish a co-fermentation with Aspergillus cristatus for releasing and transforming flavonoids of mulberry leaves (MLs) through solid-state fermentation (SSF). The present study has immeasurable importance toward making maximum use of MLs. Moreover, the findings of this study also provide new insights into understanding the release and biotransformation mechanism of flavonoids from MLs by SSF.     

紫(白)苏叶类胡萝卜素在油脂自动氧化及光敏氧化中的作用

以从紫(白)苏叶中提取出的类胡萝卜素为材料,对其在油脂自动氧化及光敏氧化中的作用进行了研究。研究表明,紫(白)苏叶类胡萝卜素在光敏氧化中起抗氧化剂的作用;在油脂自动氧化中单独添加时起氧化作用,而与VC一起则可协同抗氧化。研究还对过氧化值法(POV)和共轭双键氢过氧化物法(CDHP)测定油脂氧化进行了比较,发现同样对油脂的光敏氧化用POV法与CDHP法有较强的相关性,证明了CDHP法测定油脂氧化的科学性。