Antioxidant Activity of Potato Peel Extracts in a Fish-Rapeseed Oil Mixture and in Oil-in-Water Emulsions

The objectives of the present work were (a) to extract the phenolic fraction from the peels of two Danish varieties of potatoes, viz. Sava and Bintje, and examine their antioxidant capacity in in-vitro systems (b) to evaluate the effect of these extracts on the storage stability of a fish-rapeseed oil mixture and oil-in-water emulsions. Multiple antioxidant activity of the potato peel extracts was evident from in-vitro systems as they showed strong reducing power, radical scavenging ability, ferrous ion chelating activity and prevented oxidation in a liposome model system. The Sava variety, which showed strong antioxidant activity in in-vitro systems, was tested in oil and oil-in-water emulsions. Ethanolic extracts of Sava (≥1,600 mg/kg) prevented lipid oxidation in emulsions and in oil. Water extracts showed no antioxidant activity in oil whereas it showed pro-oxidant activity in emulsions. Thus, the results of the present study show the possibility of utilizing waste potato peel as a promising source of natural antioxidants for retarding lipid oxidation.     

Acylated Anthocyanins from Red Cabbage and Purple Sweet Potato Can Bind Metal Ions and Produce Stable Blue Colors

Red cabbage (RC) and purple sweet potato (PSP) are naturally rich in acylated cyanidin glycosides that can bind metal ions and develop intramolecular π-stacking interactions between the cyanidin chromophore and the phenolic acyl residues. In this work, a large set of RC and PSP anthocyanins was investigated for its coloring properties in the presence of iron and aluminum ions. Although relatively modest, the structural differences between RC and PSP anthocyanins, i.e., the acylation site at the external glucose of the sophorosyl moiety (C2-OH for RC vs. C6-OH for PSP) and the presence of coordinating acyl groups (caffeoyl) in PSP anthocyanins only, made a large difference in the color expressed by their metal complexes. For instance, the Al³⁺-induced bathochromic shifts for RC anthocyanins reached ca. 50 nm at pH 6 and pH 7, vs. at best ca. 20 nm for PSP anthocyanins. With Fe²⁺ (quickly oxidized to Fe³⁺ in the complexes), the bathochromic shifts for RC anthocyanins were higher, i.e., up to ca. 90 nm at pH 7 and 110 nm at pH 5.7. A kinetic analysis at different metal/ligand molar ratios combined with an investigation by high-resolution mass spectrometry suggested the formation of metal–anthocyanin complexes of 1:1, 1:2, and 1:3 stoichiometries. Contrary to predictions based on steric hindrance, acylation by noncoordinating acyl residues favored metal binding and resulted in complexes having much higher molar absorption coefficients. Moreover, the competition between metal binding and water addition to the free ligands (leading to colorless forms) was less severe, although very dependent on the acylation site(s). Overall, anthocyanins from purple sweet potato, and even more from red cabbage, have a strong potential for development as food colorants expressing red to blue hues depending on pH and metal ion.     

微波辅助提取紫薯花青素的研究

文章以紫薯为原料,在微波条件下萃取其花青素,探讨了微波的辐射时间,温度,液固比,提取剂浓度对紫薯花青素萃取的影响,并采用大孔树脂AB-8纯化提取液,将纯化后的提取液进行反相高效液相色谱分析其成分。实验结果表明,紫薯花青素微波最佳提取条件为:辐射时间60 s,温度50℃,液固比40∶1,提取剂为1%HCl-95%乙醇溶液,最佳酸醇比为50∶50。     

体外消化对蓝莓提取物抗氧化、抗癌及组分的影响

以蓝莓为原料,考察了体外消化前、后蓝莓提取物(总酚和花色苷)含量、抗氧化性、抗癌作用及花色苷组成的变化,并推测了花色苷的降解途径。分别采用福林-酚法和pH示差法测定总酚和花色苷含量;以脂质体的抑制率、DPPH和ABTS+自由基清除能力评价体外消化前后提取物的抗氧化能力;利用高效液相色谱-电喷雾二级质谱联用技术分析花色苷组成。结果表明,与未经消化的提取物相比,经肠道消化后样品总酚含量增加47.21%,花色苷含量降低71.82%,脂质体的抑制率、DPPH和ABTS+自由基清除率分别提高38.45%、29.41%和29.12%;对Hep G2肝癌细胞、A549肺癌细胞和Hela人宫颈癌细胞的生长抑制作用显著增加,蓝莓花色苷组分由12种降为9种。对胃肠消化花色苷的降解过程推测发现,矢车菊素-3-葡萄糖苷降解形成槲皮素的过程与天竺葵素-3-葡萄糖苷降解成山柰酚的过程机制相同。     

紫甘薯花青素的功能特性研究

采用抗坏血酸和BHT作为对照,测定了紫甘薯花青素的还原能力、对食用油脂的抗氧化能力及对.OH自由基和O2-.自由基的清除能力。结果表明,当浓度大到0.5mg/mL时,其还原能力接近抗坏血酸;在豆油基质中紫甘薯花青素的抗氧化活性高于BHT;在试验质量浓度范围内,紫甘薯花青素对.OH自由基的清除率为81.2%,活性略低于抗坏血酸;对O2-.自由基的清除率可达91.3%,活性强于BHT。     

Anthocyanins/chitosan films doped by nano zinc oxide for active and intelligent packaging: comparison of anthocyanins source from purple tomato or black wolfberry

The multifunctional films was prepared by blending chitosan and nano-ZnO with purple tomato anthocyanins or black wolfberry anthocyanins. The properties of films functioned by anthocyanins source and nano-ZnO content were studied. It was found purple tomato anthocyanins showed more significant color change against pH than black wolfberry anthocyanins. The nano-ZnO were widely dispersed in matrix and enhanced the compatibility of anthocyanins with chitosan. However, the anthocyanins source influenced the properties of the films more slightly than nano-ZnO addition. The tensile strength, antioxidant and antibacterial effects of the chitosan films dramatically increased after cooperated by nano-ZnO and anthocyanins, which also enhanced with increase of nano-ZnO content, whereas the elongation at break of the composite films decreased. Especially, the anthocyanin and nano-ZnO promoted the antibacterial activity of films synergistically. Composite films made from black wolfberry anthocyanins exhibited higher mechanical performance than those made from purple tomato anthocyanins but weaker antibacterial effects. The purple tomato anthocyanins/chitosan and nano-ZnO/purple tomato anthocyanins/chitosan films effectively reflected pork spoilage, changing their colors from dark green to brown, indicating the potential for applications in active and intelligent food packaging.     

Isolation,Stability, and Antioxidant Activity of Anthocyanins from Lycium ruthenicum Murray and Nitraria Tangutorum Bobr of Qinghai-Tibetan Plateau

Four anthocyanins, namely petunidin-3,5-O-diglucosides(L1), petuinidi-3-O-rutinoside(trans-p-coumaroyl)-5-O-glucosides(L2),cyanidin-3-O-(trans-p-coumaroyl)-diglucoside(N1), and pelargonidin -3-O-(trans-coumaroyl)-diglucoside (N2) have been obtained by preparative HPLC from Lycium ruthenicum Murray and Nitraria Tangutorum Bobr. The stability and antioxidant capacity of these four individual anthocyanins were carried out in this paper. For stability capacity examination, pH stability (pH 1, 3, 5, 7, 9, 11 and 13), photostability (exposed to light), and thermostability (5°C and 35°C) were systematically investigated. As for antioxidant capacity evaluation, DPPH radicals scavenging assay and ferric reducing antioxidant power (FRAP) assay were employed. The results showed that acidic solution tended to be favorable condition for all anthocyanins mentioned above. However, as the pH of solution increased, anthocyanins were becoming more unstable. In photostability and thermostability assays, the acylated anthocyanins behaved more stable than non-acylated anthocyanins. These results also indicated that the anthocyanins which had more powerful radical scavenging ability (DPPH) tended to possess stronger FRAP capacity. These data also indicated that the structures of aglycone and acyl group greatly affected the stability and antioxidant capacity of anthocyanins. Given the results obtained from our study, the high stability and antioxidant merits that the purified anthocyanins displayed made the two berries of Qinghai-Tibetan plateau become ideal resources of natural pigment.     

马铃薯皮中多酚类物质的抗氧化性研究

通过体外抗氧化体系测定马铃薯皮多酚的抗氧化活性。除超氧阴离子的能力;马铃薯皮多酚清除羟基自由基的能力;马铃薯皮多酚清除DPPH自由基的能力;马铃薯皮多酚对油脂的抗氧化能力。马铃薯皮多酚对超氧阴离子的清除率最高达18.33%,且在低浓度清除能力明显高于同浓度抗坏血酸(Vc);马铃薯皮多酚对羟基自由基的清除率最高达92.26%。对DPPH自由基清除率最高达86.08%。油脂中添加马铃薯皮多酚提取液,可以明显降低油脂的过氧化值(POV)。马铃薯皮多酚对超氧阴离子,羟基自由基和DPPH自由基都有很好的清除效果,且在一定程度上降低油脂过氧化值随时间而延长的程度,是很好的天然抗氧化剂。     

Evaluation of Antioxidant and Antiproliferative Properties of Three Actinidia (Actinidia kolomikta, Actinidia arguta, Actinidia chinensis) Extracts in Vitro

The total phenolic content, total flavonoid content, vitamin C content, and antioxidant activities of ethanol extracts from different kiwifruit varieties (Actinidia kolomikta, Actinidia arguta, Actinidia chinensis) were determined in this study. Multiple scavenging activity assays including the hydroxyl radical, O(2) (-)·radical, DPPH, and the ABTS(+) radical scavenging activity assays were used to identify the antioxidant activities of Actinidia extracts. The cell viability of HepG2 and HT-29 cells was also examined in this study. The results demonstrated that the Actinidia kolomikta extract had a higher antioxidant activity than the other two Actinidia extracts. There is a positive correlation between antioxidant activity and the polyphenols and vitamin C content in all three extracts (R(2) ≥ 0.712, p < 0.05). The Actinidia arguta extract had the highest inhibitory effect on HepG2 and HT-29 cell growth. These results provide new insight into the health functions of fruit and demonstrate that Actinidia extracts can potentially have health benefits.     

Graphene phytotoxicity in the seedling stage of cabbage, tomato, red spinach, and lettuce

The effects of graphene on root and shoot growth, biomass, shape, cell death, and reactive oxygen species (ROS) of cabbage, tomato, red spinach, and lettuce, were investigated using a concentration range from 500 to 2000 mg/L. The results of the combined morphological and physiological analyses indicate that after 20 days of exposure under our experimental conditions, graphene significantly inhibited plant growth and biomass compared to a control. The number and size of leaves of the graphene-treated plants were reduced in a dose-dependent manner. Significant effects also were detected showing a concentration-dependent increase in ROS and cell death as well as visible symptoms of necrotic lesions, indicating graphene-induced adverse effects on cabbage, tomato, and red spinach mediated by oxidative stress necrosis. Little or no significant toxic effect was observed with lettuce seedlings under the same conditions. The potential effect of graphene largely depends on dose, exposure time, and plant species and deserves further attention.     

Antioxidant and radical-scavenging activities of buckwheat seed components

The search for endogenous components in food ingredients exhibiting antioxidant activity has been intensified in order to eliminate synthetic antioxidants. Tocopherols are widely used as natural antioxidants, although their protective ability is not always sufficient. Buckwheat seed components were evaluated for antioxidant and free radical-scavenging activities using solvents of different polarities to isolate components from hulls and groats. Components extracted from buckwheat hulls were pro-oxidant in canola oil. Antioxidant activity of extracts from buckwheat groats increased when more polar solvents were used for extraction. The highest activity was observed for the methanolic extract. Radical-scavenging activity of buckwheat extracts was analyzed with DPPH (2,2-diphenyl-2-picryl-hydrazyl). This activity increased when the more polar solvents were used for extraction, with the highest activity observed for the methanolic extract. It was also observed that the radical scavenging effectiveness of extracts was concentration dependent. Analysis revealed the presence of tocopherols in the hexane extract, while methanolic extracts were rich in phenolic acids and flavonoids.     

Effect of Enzymatic Hydrolysis on the Antioxidant Activity of Red and Green Seaweeds and Characterization of the Active Extracts

In the present study, the effect of enzymatic hydrolysis on the antioxidant activity of three red seaweeds (Chondria cornuta, Chondria dasyphylla, and Murrayella periclados) and two green seaweeds (Cladophora sp. and Ulva lactuca) from the Kuwait coast were evaluated. The seaweeds were hydrolyzed with five carbohydrases and three proteases, and the resulting extracts were tested for antioxidant activity. The total phenolic content and yield of the extracts varied greatly depending upon the species and enzyme used for hydrolysis. Of the 40 enzymatic extracts screened for antioxidant activity, the Viscozyme and Alcalase extracts of M. periclados, Neutrase and Ultraflo extracts of Cladophora sp., and Neutrase extracts of C. cornuta had high antioxidant activity compared to other enzymatic extracts in various in vitro assays. Fractionation of the extracts revealed that the radical scavenging and reducing power of the extracts were mainly due to phenolic fractions. In contrast, the iron-chelating ability was mainly due to protein fractions. The level of prevention of lipid oxidation in the liposome model system varied for different fractions of extracts and did not correlate with total phenolic content and other antioxidant properties. The results of the study show that, by hydrolyzing seaweeds with specific enzymes, customized seaweed extracts with specific bioactivity could be obtained.     

9种常见植物秸秆抗氧化活性的比较研究

采用DPPH法、α-脱氧核糖氧化法(对·OH的清除能力)和普鲁士蓝法(还原能力)3种方法测定提取物抗氧化活性,比较了9种常见植物秸秆的抗氧化活性。结果显示:凤眼莲叶和法桐落叶在3种测试方法中均显示出了强抗氧化能力,而稻草和麦秆均为抗氧化能力较弱的植物。各种抗氧化能力测试方法之间存在一定的相关性。     

酸石榴汁红色素的树脂吸附及石榴提取物的抗氧化作用研究

研究了7种吸附树脂对酸石榴汁红色素的吸附,及酸石榴各部分提取物对DPPH(1,1-Diphenyl-2-picrylhydrazyl;1,1-二苯基-2-苦基肼自由基)的清除作用,并且将提取出的酸石榴汁红色素添加到化妆品配方中,探讨了该配方对于延缓衰老的功效.实验结果表明:HPD-300对酸石榴汁红色素的吸附效果最好;...     

Antioxidant activity of grape extracts in a lecithin liposome system

Extracts of 14 different grapes were tested for their antioxidant activities in a copper-catalyzed lecithin liposome oxidation assay and analyzed for their phenolic components by high-performance liquid chromatography (HPLC). The total phenolic contents of the grape extracts varied from 176 to 1236 mg gallic acid equivalents (GAE)/L. Extracts of red wine grape varieties contained higher concentrations of phenolics than other varieties. When compared at the same 20 μM GAE basis, the grape extracts inhibited formation of conjugated diene hydroperoxides by 25.1 to 67.9%, and hexanal formation by 49.3 to 97.8%. Extracts of red table grape varieties Red Globe and Emperor and white wine grape varieties Chardonnay and Sauvignon Blanc gave the highest antioxidant activities. The relative percentage inhibition of conjugated dienes and hexanal correlated with total phenols (r=0.86 and 0.89). HPLC analyses showed that anthocyanins were the most abundant phenolic compounds in extracts of red grapes, and flavonols were most abundant in extracts of white grapes.     

Betalain, Acid ascorbic, phenolic contents and antioxidant properties of purple, red, yellow and white cactus pears

Commercialization of cactus pears based on their antioxidant properties can generate competitive advantages, and these can turn into business opportunities and the development of new products and a high-value ingredient for the food industry. This work evaluated the antioxidant activities (1,1-diphenyl-2-picrylhydrazyl radical-scavenging, protection against oxidation of a β-carotene-linoleic acid emulsion, and iron (II) chelation), the content of total phenolic compounds, ascorbic acid, betacyanin, betaxanthin and the stability of betacyanin pigments in presence of Cu (II)-dependent hydroxyl radicals (OH•), in 18 cultivars of purple, red, yellow and white cactus pear from six Mexican states. Our results indicated that the antiradical activities from yellow and white cactus pear cultivars were not significantly different (p < 0.05) and were lower than the average antiradical activities in red and purple cultivars. The red cactus pear from the state of Zacatecas showed the highest antioxidant activity. The free radical scavenging activity for red cactus pears was significantly correlated (p < 0.05) to the concentration of total phenolic compounds (R² = 0.90) and ascorbic acid (R² = 0.86). All 18 cultivars of cactus pears studied showed significant chelating activity of ferrous ions. The red and purple cactus pears showed a great stability when exposed to OH•.     

In Vitro Interaction of 5-Aminoorotic Acid and Its Gallium(III) Complex with Superoxide Radical,Generated by Two Model Systems

Increased levels of the superoxide radical are associated with oxidative damage to healthy tissues and with elimination of malignant cells in a living body. It is desirable that a chemotherapeutic combines pro-oxidant behavior around and inside tumors with antioxidant action near healthy cells. A complex consisting of a pro-oxidant cation and antioxidant ligands could be a potential anticancer agent. Ga(III) salts are known anticancer substances, and 5-aminoorotic acid (HAOA) is a ligand with antioxidant properties. The in vitro effects of HAOA and its complex with Ga(III) (gallium(III) 5-aminoorotate (GaAOA)) on the in vitro accumulation of superoxide and other free radicals were estimated. Model systems such as potassium superoxide (KO₂), xanthine/xanthine oxidase (X/XO), and rat blood serum were utilized. Data suggested better antioxidant effect of GaAOA compared to HAOA. Evidently, all three ligands of GaAOA participated in the scavenging of superoxide. The effects in rat blood serum were more nuanced, considering the chemical and biochemical complexity of this model system. It was observed that the free-radical-scavenging action of both compounds investigated may be manifested via both hydrogen donation and electron transfer pathways. It was proposed that the radical-scavenging activities (RSAs) of HAOA and its complex with Ga(III) may be due to a complex process, depending on the concentration, and on the environment, nature, and size of the free radical. The electron transfer pathway was considered as more probable in comparison to hydrogen donation in the scavenging of superoxide by 5-aminoorotic acid and its gallium(III) complex.     

Antioxidant activity and free radical‐scavenging capacity of ethanolic extracts of thyme,oregano, and marjoram

Phenolic compounds were extracted from thyme (Thymus vulgaris L.), oregano (Origanum vulgare L.) and marjoram (Origanum majorana L.) with 95% ethanol. A number of antioxidant and radical‐scavenging capacity tests were performed on the prepared extracts using colorimetric assays and model system studies. Specifically, these included determining the content of total phenolics, antioxidant efficacy in a linoleic acid‐ferric thiocyanate model system, reducing power, scavenging effect on 2,2'‐diphenyl‐1‐picrylhydrazyl radical, and hydroxyl radical‐scavenging activity by electron paramagnetic resonance spectroscopy. Moreover, the efficacies of the prepared herb extracts were investigated in a real‐life food product: the stabilization of butter against oxidation.