Antioxidant,anti-amylase and anti-glycation potential of brans of some Sri Lankan traditional and improved rice (Oryza sativa L.) varieties

Brans of 23 traditional and 12 improved (both red and white) rice varieties in Sri Lanka were screened for anti-amylase and anti-glycation activities in vitro. Varieties which showed the highest inhibitory activities at screening were further investigated for anti-glucosidase and glycation reversing as anti-diabetic properties. The same varieties were studied for selected antioxidant properties. Significantly high anti-amylase and anti-glycation activities were observed for bran extracts of red varieties compared to white varieties at screening. Traditional red rice varieties, Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti, exhibited significant and dose dependent anti-amylase, anti-glycation and glycation reversing activities. These varieties also showed marked antioxidant properties. It is concluded that brans of Sri Lankan traditional red rice varieties Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti may be potential food supplements for diabetes.     

玫瑰茄粗多糖清除DPPH自由基活性研究

以玫瑰茄干花萼为原料,利用水浸醇析法提取玫瑰茄粗多糖,其抗氧化活性用清除1,1-二苯基苦基苯肼（DPPH）自由基的能力进行评价。结果表明,玫瑰茄粗多糖具有良好的抗氧化活性,其浓度在0.551~2.150 mg/mL范围内,与清除率呈较好的线性关系：y=28.7684x+39.43208,R=0.973。     

Characterizing the pigmented traditional rice cultivars grown in temperate regions of Kashmir (India) for free and bound phenolics compounds and in vitro antioxidant properties

The purpose of the research was to identify the phenolic and flavonoid compounds of seven different traditional pigmented whole rice cultivars grown in the temperate regions of Kashmir so as to study their relationship with in vitro antioxidant capacities. The completely pigmented rice cultivars were found to have higher phenolic, flavonoid, anthocyanin contents and exhibited higher antioxidant capacities than the light colored and sparely colored rice cultivars. A total of 40 compounds had been identified in the analyzed rice cultivars that were found to be distributed in 6 major categories with 6-phenolics, 6-flavonoids, 11-hydroxycinnamic acid derivatives, 7-hydroxybenzoic acid derivatives, 3-anthocyanins and 7-flavonoid glucosides of different flavonoid compounds. Among the free and bound fractions for each cultivars the light and sparsely colored depicted higher content of phenolics and in vitro antioxidant properties in bound faction, while the completely pigmented cultivars showed higher antioxidant properties in free fractions. The anthocyanins quercetin-3-O-galactoside, cyanidin-3-O-rutinoside and pelargonidin-3-O-diglucoside had been identified by LC-MS existing in the free fractions of the analyzed rice cultivars whereas, the free fraction of acetone + H₂O possessed higher percentage of phenolic compounds as compared to methanolic extracts and bound fractions. The black colored cultivars possessed higher DPPH scavenging activity and lipid peroxidation inhibition.     

陈年普洱茶香气成分及清除DPPH自由基活性研究

为研究陈年普洱茶的特征风味成分及生物活性,采用顶空-固相微萃取-气质联用法测定了3种陈年普洱茶中挥发性物质,结合质谱和保留指数共鉴定出57种化合物,其中甲氧基酚类、醇类及酮类化合物为主要香气成分。同时采用比色法测得3种普洱茶的沸水提取物的茶多酚含量分别为(41.91±1.98)、(43.84±2.56)及(41.28±2.57) mg GAE/(g·DW),并对3种普洱茶的1,1-二苯基苦基苯肼(DPPH·)自由基清除效果进行研究。结果表明3种普洱茶均具有较好的清除DPPH自由基能力,且呈剂量依赖性,测得3种普洱茶提取物清除DPPH·自由基的IC₅₀分别为(129.03±0.25)、(139.47±1.58)及 (152.57±3.34) mg GAE/L。     

山西老陈醋抗氧化活性及其机理

对山西老陈醋的抗氧化性和抗氧化机理进行了研究。结果表明,山西老陈醋中多酚的含量达到4.865 mg/mL;50,200μL山西老陈醋对DPPH自由基(1,1-二苯基-2-三硝基苯肼)的清除能力分别为50.2%和68.7%,对亚油酸体系自氧化抑制率分别为69.7%和78.7%。说明山西老陈醋具有较强的总抗氧化能力和较强的清除DPPH自由基能力。     

野草香醇提物抗氧化活性研究

运用DPPH、ABTS两种分光光度法进行体外抗氧化活性筛选来研究野草香的体外抗氧化作用。结果显示野草香乙醇总提取物不同萃取部位均具有良好的消除DPPH·和ABTS·的能力,在DPPH和ABTS方法中,水部分对DPPH自由基消除率最高,IC50值为15.66 mg/m L;乙酸乙酯部分对ABTS自由基消除率最高,IC50值为14.04mg/m L。这说明野草香乙醇总提取物均有一定消除DPPH和ABTS自由基的能力,野草香各个粗提物部分对DPPH及ABTS自由基的清除率均与质量浓度呈量效关系,总提取物和不同萃取部分的抗氧化活性存在着差异。     

热处理对甜玉米酚类物质含量及抗氧化能力的影响

为研究热处理对甜玉米中酚类和类黄酮物质含量及抗氧化能力的影响,分别测定新鲜甜玉米粒、甜玉米浆、甜玉米羹(将新鲜甜玉米粒打浆破碎后分别在105～125℃下高压灭菌处理25 min)3类材料提取物中的多酚和类黄酮物质含量。以FRAP、ABTS和DPPH 3个抗氧化指标来评价甜玉米提取物抗氧化能力和清除自由基能力。结果表明,酚类、类黄酮含量和FRAP值都随处理温度的升高而升高;ABTS和DPPH自由基清除能力也较未经热处理的甜玉米强;热处理能显著增强甜玉米的抗氧化能力。     

Purification and Characterization of a New DPPH Radical Scavenging Peptide from Shrimp Processing By-products Hydrolysate

A peptide with high antioxidant activity was isolated and identified from shrimp processing by-products hydrolysate. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity was used to evaluate the antioxidant activity of fractions. The purified antioxidant peptide was identified as Ser-Val-Ala-Met-Leu-Phe-His (804.4 Da) by electrospray ionization tandem mass spectrometry. The purified peptide at 50 μg/mL showed antioxidative activity of 65.7 ± 0.9%, which was 3.18-fold higher compared with the first step separation by ion-exchange chromatography. It is possible to produce natural antioxidative peptides from shrimp processing by-products hydrolysate. The high antioxidant activity may be due to the presence of Phe-His segment at the C-terminus of the peptide.     

玉米须萃取物的抗氧化活性

将玉米须乙醇提取物再用氯仿、乙酸乙脂、正丁醇和甲醇分别萃取,获得极性不同的5个组分,比较这5种不同溶剂萃取物在二苯基苦基苯肼(DPPH)体系及在Fe2 诱发卵黄脂蛋白多不饱和脂肪酸(PUFA)过氧化体系中的抗氧化活性。结果表明:在DPPH体系中,正丁醇萃取物的抗氧化活性最强,氯仿萃取物次之;在Fe2 诱发脂蛋白PUFA过氧化体系中,氯仿萃取物的抗氧化活性最强,乙酸乙酯萃取物次之。结果还表明,这5不同溶剂萃取物在不同测试体系中的抗氧化活性顺序不同。     

Three new homoisoflavanones from the bulbs of Ledebouria floribunda

Three new homoisoflavanones, namely ledebourin A (1), ledebourin B (2) and ledebourin C (3) were isolated from the bulbs of Ledebouria floribunda. Their structures were elucidated on the basis of detail spectroscopic analyses. This is the first report of this type of homoisoflavanones. Ledebourin B (2) and ledebourin C (3) exhibited potent antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging compared to the positive controls, the well-known antioxidant BHT and BHA.