Purification and identification of rice bran (Oryza sativa L.) phenolic compounds with in-vitro antioxidant and antidiabetic activity using macroporous resins

This study was designed to establish an efficient purification method for phenolic compounds from rice bran and to acquire insightful knowledge of purification impact on its chemical constituents, antioxidant and antidiabetic activity. Among the eight macroporous resins investigated, HPD-300 resin was verified to bosses superior adsorption and desorption qualities for the extract. Purification parameters were optimised. Eighteen phenolic compounds were identified using HPLC-PDA, the contents of ferulic acid and syringaldehyde were significantly (P < 0.05) higher than the other constituents. However, phenolic compounds concentrations varied significantly (P < 0.05) after HPD-300 resin purification. In addition, the extract exhibited a significant (P < 0.05) increase in total flavonoid contents, in vitro antioxidant (DPPH and FRAP) and antidiabetic (α-glucosidase and BSA-glycation inhibition) activity after HPD-300 resin treatment. These findings indicate that selection of resin and applying optimal purification condition is an appropriate economical approach for obtaining bioactive phenolic compounds from rice bran.     

Phenolic composition and antioxidant activity of white mulberry (Morus alba L.) fruits

Eight major mulberry cultivars [Nakhonratchasima 60 (NS 60), Buriram 60 (BR 60), Chumphon (CP), Wavee (WV), Chaingmai (CM), Pikultong (PT), Kamphaengsaen (KS) and Kamnanchul (KJ)] cultivated in Thailand were assessed for their flavonoid and phenolic acid composition using HPLC and tested for antioxidant potential using 2,2‐diphenyl‐1‐picrylhydrazyl hydrate (DPPH) assay. The total phenolic content (TPC) ranged from 104.78 to 213.53 mg GAE/100 g DW, and total flavonoid content (TFC) ranged from 69.58 to 211.01 mg CE/100 g DW. The major flavonoid compounds in mulberry fruit cultivars were (+)‐catechin (309.26–750.01 mg/100 g DW), procyanidin B1 (62.59–224.41 mg/100 g DW), quercetin (5.36–58.42 mg/100 g DW), rutin (18.73–26.90 mg/100 g DW) and (?)‐epicatechin (8.47–29.21 mg/100 g DW). Gallic acid, cinnamic acid and p‐hydroxybenzoic acid were found to be the major phenolic acids in mulberry fruit cultivars. The gallic acid and cinnamic acid contents ranged from 7.33 to 23.90 mg/100 g DW and from 11.64 to 15.05 mg/100 g DW, respectively. p‐Hydroxybenzoic acid content ranged from 1.77 mg/100 g DW (PT) to 7.13 mg/100 g DW (KJ). DPPH‐scavenging ability was excellent for ethanolic extract of NS 60, and EC₅₀ value of NS 60 (241.83 μg mL^?1) was significantly lower than those of the others (P < 0.05). TPC and TFC of the mulberry fruit were positively correlated with the DPPH‐scavenging ability.     

Antioxidant and immunomodulatory activities of sulphated polysaccharides from purple glutinous rice bran (Oryza sativa L.)

This research aimed to extract polysaccharides and improve the property of sulphate‐modified purple glutinous rice bran, cv. Kum Doi Saket. The effects of temperature, ratio of sulphur trioxide–trimethylamine (STMA) to sample and reaction times were studied. The results showed that the degree of substitution (DS) of sulphated polysaccharides was 0.01–0.53. Low molecular weight sulphated polysaccharides were obtained, and the functional groups of the sulphated polysaccharides were confirmed using FT‐IR. No enhancement of the antioxidant activity of the sulphated polysaccharides was observed. Interestingly, immunomodulatory activity, including inducing cytokine production (iNOS, TNF‐α, IL‐1β and IL‐10) via up‐regulated mRNA expression, was significantly increased by 10–86% when compared to the crude polysaccharides.     

糯米糠抗氧化肽的制备工艺及自由基清除能力研究

为开发利用糯米糠资源,研究了糯米糠抗氧化肽的制备工艺及自由基清除能力。选取中性蛋白酶为水解酶,以抗氧化肽还原力为指标,采用单因素实验和正交实验方法优化糯米糠抗氧化肽的制备工艺。结果表明,制备糯米糠抗氧化肽的最佳工艺条件为糯米蛋白底物浓度4%、[E]/[S]2%、pH7、酶解温度40℃、酶解时间6h,在该条件下制备的糯米糠抗氧化肽对羟基自由基和超氧阴离子自由基的清除能力明显优于米糠抗氧化肽,且存在一定的量效关系,提示糯米糠抗氧化肽可用作功能性食品或天然抗氧化剂被深入研究和开发利用。      

雪莲果叶酚酸抗氧化能力的研究

通过测定雪莲果叶酚酸提取物的还原能力和对化学模拟体系中羟自由基(.OH)、超氧阴离子自由基(O2-.)及二苯代苦味肼基自由基(DPPH.)的清除能力,研究了雪莲果叶酚酸提取物的体外抗氧化活性。结果表明:雪莲果叶酚酸提取物具有较强的抗氧化能力,对自由基有明显清除作用,并且随着雪莲果叶酚酸浓度的增加,其抗氧化能力有显著增强的趋势。     

米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响

以新鲜米糠为原料贮藏0、1、3、5、10 d得到不同酸败程度的米糠,稳定化和脱脂后制备米糠可溶性膳食纤维,研究米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响。结果表明:随着新鲜米糠贮藏时间的延长,米糠可溶性膳食纤维的还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH、O_2~-·能力均先上升后下降;米糠可溶性膳食纤维还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH在新鲜米糠贮藏5 d时达到最大值,分别为0.943(OD_(700))、35.16%、32.28%、73.51%和13.83%,米糠可溶性膳食纤维清除O_2~-·能力在新鲜米糠贮藏1 d达到最大值,为60.58%。     

Total phenolic content and antioxidant properties of eclipse black beans (Phaseolus vulgaris L.) as affected by processing methods

ABSTRACT:  The effects of soaking, boiling, and steaming processes on the phenolic components and antioxidant activity of black beans were investigated. All processed beans exhibited significantly ( P < 0.05) lower antioxidant activities than raw beans in total phenolic content (TPC), DPPH free radical scavenging activity (DPPH), and oxygen radical absorbing capacity (ORAC). Steaming processes resulted in a greater retention of TPC and ORAC values than the boiling processes. Pressure boiling shortened processing time compared to regular boiling, resulted in insignificant differences in TPC, but significantly increased in ORAC as compared to the regular boiling method. Pressure steaming resulted in significant decreases in TPC, DPPH, while significantly increased in ORAC compared to regular steaming. Greater TPC, DPPH, and ORAC values were detected in boiling water than in the soaking and steaming water. Mass balance analysis showed that boiling caused more dry solid loss than steaming. All of these results indicated that processing methods significantly changed contents and activities of antioxidant components of black beans. Steam processing exhibited several advantages in appearance and texture of the cooked product, shortening processing time, and in greater retention of TPC and antioxidant activities. Steam processing may be used to develop high-quality health-promoting black bean products.     

Total phenolic content and DPPH radical scavenging activity of lettuce (Lactuca sativa L.) grown in Colorado

Total phenolic content (TPC) and antioxidant capacity of lettuce were evaluated using the Folin-Ciocalteu method and DPPH assay, respectively, on 25 cultivars of lettuce, including leaf, romaine, crisphead, and butterhead types, cultivated over two harvest periods. Leaf lettuce possessed the highest TPC and highest DPPH scavenging ability, followed by romaine, butterhead and Batavia (crisphead subtype). Within a lettuce type, red pigmented lettuce cultivars had higher TPC and antioxidant capacity than did green cultivars grown under the same conditions. In addition, lettuce harvested in July possessed higher TPC and antioxidant capacity than did lettuce harvested in September, suggesting that environmental conditions could influence the phenolic content and antioxidant activity of lettuce. These results suggest that Colorado grown lettuce may serve as potential dietary sources of natural phenolic antioxidants.     

Effect of fermentation by Bacillus subtilis on antioxidant and cytotoxic activities of black rice bran

Black rice bran was fermented with Bacillus subtilis KU3 isolated from Korean traditional food, Kimchi. Antioxidant and cytotoxic activities of the fermented black rice bran were investigated. Total phenolic and anthocyanin contents decreased from 171.54 mg GAE g^?1 and 2.31 mg g^?1 to 139.13 mg GAE g^?1 and 2.12 mg g^?1, respectively, after fermentation. Antioxidant activities determined by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, β‐carotene bleaching and ferric thiocyanate assay were correlated with total phenolic and anthocyanin contents. Non‐fermented black rice bran extract (NFBE) showed greater antioxidant activities than fermented black rice bran extract (FBE). Cytotoxic activities measured by MTT assay showed that both NFBE and FBE had over 50% activities. The cytotoxic activities of FBE against MCF‐7 and HeLa cells were 71.65% and 68.07%, respectively, at 8.0 mg mL^?1, but those of NFBE were lower than 50%. These results suggested that the cytotoxic activity of black rice bran improved through fermentation, while antioxidant activity reduced.     

A comparative study on phenolic profile,vitamin C content and antioxidant activity of Italian honeys of different botanical origin

The aim of our study was to identify and quantify the phenolic acids, flavonoids and vitamin C and to evaluate the antioxidant activity in ninety Italian honeys of different botanical origins (chestnut, sulla, eucalyptus, citrus and multifloral). The results showed that total phenolic and flavonoid contents varied from 11.08 to 14.26 mg GAE per 100 g honey and from 5.82 to 12.52 mg QE per 100 g honey, respectively. HPLC–UV analysis showed a similar but quantitatively different phenolic profile of the studied honeys. Vitamin C is present in all samples. Multifloral honey showed the highest amount of the detected total phenolic compounds and the highest vitamin C content. The DPPH value varied from 55.06 to 75.37%. Among the unifloral honeys, chestnut honey presented the highest levels of phenolic acids, flavonoids and vitamin C, which are closely associated with its high antioxidant activity. The results show that honey contains high amount of biologically active compounds, which play an important role in defining the nutraceutical quality of the product, and that the distribution of these compounds is influenced by the botanical origin.     

A comparative study on different concentration methods of extracts obtained from two raspberries (Rubus idaeus L.) cultivars: evaluation of anthocyanins and phenolics contents and antioxidant activity

The effects of conventional (CV) and microwave (MW) heating on total soluble solid (TSS) content, total anthocyanin content (TAC), total phenolic content (TPC) and antioxidant activity of raspberry juice obtained from two cultivars of Amol (AM) and Siyahkal (SK) were scrutinised. Antioxidant activity of the juices was measured by 2,2 diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging capacity and expressed as EC₅₀ value. In the both methods, the concentration rate constant for the juices was significantly decreased by increasing operational pressure from 12 to 100 kPa (P < 0.05). A first‐order reaction kinetic model was successfully fitted for the degradation of monomeric anthocyanins at all operating pressures. The results also showed that thermal treatment of MW compared CV in both SK and AM cultivars caused a lower decrease in the TAC, TPC and antioxidant activity. Moreover, the changes in trend of the antioxidant activities due to the thermal treatment were positively correlated with the TPC (r = 0.74, P < 0.05) and TAC (r = 0.61, P < 0.05).     

A preliminary study of the protease activities in germinating brown rice (Oryza sativa L.)

BACKGROUND: Proteases hydrolyse storage proteins to provide precursors for perpetuating species. The aim of this study was to investigate and characterise different proteases in germinating brown rice. RESULTS: The protease activity of brown rice increased sevenfold during 7 days of germination. It was highest on day 6 when determined at pH 3.5. With casein as substrate the proteases showed two catalytic groups: acidic proteases with an optimal pH of 3.5 and alkaline proteases with an optimal pH of 8.0. The acidic protease activity was inhibited by Ba²⁺ and Pb²⁺ but stimulated by Zn²⁺, while the alkaline protease activity was inhibited by Ca²⁺ and Pb²⁺ but stimulated by Mg²⁺ and Zn²⁺. SDS‐gelatin‐PAGE assay showed two protease activity bands at pH 3.5, while two different bands with higher molecular weights were observed at pH 8.0. Inhibition assay revealed that pepstatin A and E‐64 inhibited 67.63 and 38.26% respectively of the protease activity at pH 3.5, indicating the presence of aspartic and cysteine proteases. Metalloproteases played a major role under alkaline conditions (88.37% inhibition with EDTA). CONCLUSION: Germinated brown rice proteases fall into different classes with different properties. This study is helpful for their further purification. Copyright © 2010 Society of Chemical Industry     

超声-微波协同提取富硒米糠蛋白的工艺优化及其抗氧化活性评价

为解决富硒米糠蛋白提取率低、提取时间长及提取后功能特性下降等问题,以脱脂富硒米糠粉为原料,通过单因素试验和正交试验对超声-微波协同提取富硒米糠蛋白的工艺进行优化,通过与超声辅助法、微波辅助法和碱提法比较,探究该提取方法对富硒米糠蛋白的提取效果、抗氧化活性以及提取后米糠颗粒表面形貌变化的影响。结果表明,超声-微波协同提取富硒米糠蛋白的最佳工艺条件为超声功率600 W、微波功率500 W、提取时间20 min、料液比1∶40,在此条件下富硒米糠蛋白的提取率为86.94%,与超声辅助法、微波辅助法、碱提法相比富硒米糠蛋白提取率分别提高了40.96%、48.00%、53.50%,并且提取的富硒米糠蛋白抗氧化能力和硒含量更高。扫描电镜结果显示,超声-微波协同提取后米糠颗粒表面疏松卷曲,完整皮层结构消失,说明超声-微波协同能通过强烈破坏米糠颗粒结构增加富硒米糠蛋白的提取率,并提高其抗氧化活性。综上,超声-微波协同提取技术能够促进富硒米糠蛋白的提取并提高其抗氧化活性。     

超声波处理对红葡萄酒总酚、总黄酮含量及自由基清除活性的影响

应用超声波处理红葡萄酒,探讨超声因素（超声频率,超声功率,超声处理温度,超声时间）对红葡萄酒中总酚、总黄酮含量及自由基清除活性的影响。结果表明超声处理会使红葡萄酒总酚含量、总黄酮含量与自由基清除活性显著降低（p<0.05）。超声处理红葡萄酒后,其抗氧化活性与其总酚含量呈高度正相关,回归方程为y=0.0270x+38.806（R2=0.9007,p<0.01）;其抗氧化活性与其总黄酮含量亦存在一定线性关系,回归方程为y=0.0592x+37.357（R²=0.4970,p<0.05）。在本文实验条件下根据实验结果可以推知,超声处理后红葡萄酒自由基清除活性的降低,部分是由于总酚含量和总黄酮含量降低所引起的。      

Evaluation of chemical constituents and antioxidant activity of sweet cherry (Prunus avium L.) cultivars

This research was undertaken to evaluate the sugars, organic acids, phenolic compositions and antioxidant capacities of sweet cherry cultivars (Van, Noir de Guben, Larian and 0‐900 Ziraat) grown in Turkey. High‐performance liquid chromatographic methods were used to identify and quantify four sugars (sucrose, glucose, fructose and sorbitol) and four organic acids (malic, citric, shikimic, and fumaric acid). The major organic acid was found as malic acid (8.54–10.02 g kg^?1 of FW). With regard to sugars, glucose was present in the largest amounts (44.71–48.31 g kg^?1 of FW) for sweet cherry cultivars. The sum of sugars ranged from 103.87 (Larian) to 113.13 g kg^?1 of FW (0‐900 Ziraat) and that of organic acids from 12.01 (0‐900 Ziraat) to 14.17 g kg^?1 of FW (Noir de Guben). A total of eleven phenolic compounds were identified and quantified in sweet cherry cultivars, including hydroxycinnamic acids (3), anthocyanins (5), flavan‐3‐ols (2) and flavonol (1) compounds. Total phenolic contents ranged from 88.72 (Van) to 239.54 (Noir de Guben) mg/100 g of FW, while antioxidant activities ranged from 2.02 to 7.75 μm Trolox equivalents g^?1 of FW.     

蒸汽爆破处理对麦麸的酚酸组成及其抗氧化活性的影响

该试验旨在研究蒸汽爆破处理对小麦麸皮的酚酸组成及抗氧化活性的影响。将麦麸在不同处理压力(0.5,1.5,2.5 MPa)和不同处理时间(30,90 s)条件下进行蒸汽爆破预处理。通过水解和碱提的方法,将得到的麦麸进行提取,得到游离酚酸和结合酚酸 2部分,对其中的几种主要酚酸,如香草酸、丁香酸, 4-香豆酸,阿魏酸进行研究。结果表明, 4种主要酚酸的含量在蒸汽爆破处理后均有所提高,其中阿魏酸的含量最高,结合酚酸中由未处理时的 57.232 μg/g提高到了 1454.092 μg/g。该试验还进行了总酚测定,抗氧化活性的测定。通过总酚的测定可以看出,蒸汽爆破处理后,总酚的含量高于未处理麦麸,且随着处理强度的增加,呈现先增加后减少的趋势,在处理条件为 2.5 MPa,30 s,总酚含量最高,约为未处理时的 9倍。抗氧化试验得到的变化趋势与总酚呈现相似的规律,与未进行蒸汽爆破预处理的麦麸相比,处理后的麦麸表现出了更高的 1,1-二苯基 -2-三硝基苯肼(DPPH)和 2,2-联氮 -二(3-乙基 -苯并噻唑 6-磺酸)二铵盐(ABTS)自由基清除率,以及在亚油酸体系中的抗氧化活性和还原能力。当处理条件为 2.5 MPa,30 s时,抗氧化活性表现最高。由此可得到, 2.5 MPa 30 s是蒸汽爆破处理麦麸的最佳条件,此时麦麸中酚酸含量和抗氧化活性均较优,为以后麦麸中酚类物质的深度开发利用提供理论支持。     

蒸汽爆破处理对麦麸的酚酸组成及其抗氧化活性的影响

该试验旨在研究蒸汽爆破处理对小麦麸皮的酚酸组成及抗氧化活性的影响。将麦麸在不同处理压力(0.5,1.5,2.5 MPa)和不同处理时间(30,90 s)条件下进行蒸汽爆破预处理。通过水解和碱提的方法,将得到的麦麸进行提取,得到游离酚酸和结合酚酸 2部分,对其中的几种主要酚酸,如香草酸、丁香酸, 4-香豆酸,阿魏酸进行研究。结果表明, 4种主要酚酸的含量在蒸汽爆破处理后均有所提高,其中阿魏酸的含量最高,结合酚酸中由未处理时的 57.232 μg/g提高到了 1454.092 μg/g。该试验还进行了总酚测定,抗氧化活性的测定。通过总酚的测定可以看出,蒸汽爆破处理后,总酚的含量高于未处理麦麸,且随着处理强度的增加,呈现先增加后减少的趋势,在处理条件为 2.5 MPa,30 s,总酚含量最高,约为未处理时的 9倍。抗氧化试验得到的变化趋势与总酚呈现相似的规律,与未进行蒸汽爆破预处理的麦麸相比,处理后的麦麸表现出了更高的 1,1-二苯基 -2-三硝基苯肼(DPPH)和 2,2-联氮 -二(3-乙基 -苯并噻唑 6-磺酸)二铵盐(ABTS)自由基清除率,以及在亚油酸体系中的抗氧化活性和还原能力。当处理条件为 2.5 MPa,30 s时,抗氧化活性表现最高。由此可得到, 2.5 MPa 30 s是蒸汽爆破处理麦麸的最佳条件,此时麦麸中酚酸含量和抗氧化活性均较优,为以后麦麸中酚类物质的深度开发利用提供理论支持。