软枣猕猴桃总黄酮体外抗氧化活性

研究软枣猕猴桃总黄酮体外抗氧化活性,采用分光光度法测定软枣猕猴桃总黄酮对DPPH自由基、超氧阴离子自由基(O2－ ·)、羟自由基( ·OH)清除能力,对铁离子的还原能力以及对脂质体过氧化的抑制作用,并与VC比较。结果表明,软枣猕猴桃总黄酮具有较强清除DPPH自由基的能力和还原力,可有效抑制脂质过氧化,对O2－ ·、 ·OH有一定的清除作用,且抗氧化作用与软枣猕猴桃总黄酮含量呈正相关,软枣猕猴桃总黄酮具有显著的抗氧化活性。     

4-Oxo-2-nonenal as a pro-oxidant during the autoxidation of methyl linoleate in bulk phase

The effect of aldehydic lipid peroxidation products on the autoxidation of methyl linoleate (MeL) was studied at 60 °C in bulk phase. Addition of 4-oxo-2-nonenal (ONE) to MeL accelerated the formation of MeL hydroperoxides. Other tested aldehydes showed no effect on the rate of MeL autoxidation. The pro-oxidative effect of ONE disappeared when pre-existing peroxides and transition metals were removed from MeL. Further addition of ferric ion to the peroxide- and metal-free MeL recovered its pro-oxidative effect. ONE reduced ferric ion to ferrous ion effectively. Furthermore, it had a chelating ability with ferrous ion. The results suggest that the pro-oxidative effect of ONE is due to its ability to reduce transition metals and to chelate the reduced form of metal ions. Thus, ONE could accelerate the metal-dependent lipid peroxidation.     

Ferric Ions Reduce the Antioxidant Activity of the Phenolic Fraction of Virgin Olive Oil

ABSTRACT: The antioxidant activity of relatively polar extracts from virgin olive oil was investigated in sunflower oil stripped of tocopherols and in tocopherol-stripped sunflower oil-in-water emulsions. The extracts were found to be effective as antioxidants in both media in the absence of added metal ions. However, the antioxidant activity was markedly reduced by the presence of added ferric chloride. In sunflower oil-in-water emulsions (pH 5.4) containing ferric chloride, all concentrations of olive oil polyphenols exhibited pro-oxidant effects. It appears that the reducing action of olive oil polyphenols accelerates oxidation of oil and especially of emulsions containing Fe (III) by reducing ferric ions to ferrous ions, which are effective pro-oxidants during storage.     

体外模拟胃肠消化过程中猕猴桃抗氧化成分及活性的变化

研究猕猴桃果浆和果汁在体外模拟胃肠消化过程中多酚黄酮类物质含量及抗氧化活性的变化规律。采用铁还原力,以及DPPH自由基、超氧阴离子自由基、羟自由基清除法测定抗氧化性。结果显示,消化后多酚和黄酮物质释放量增加。果浆消化后最大释放量分别为消化前的1.62倍和2.40倍;果汁消化后多酚、黄酮的最大释放量分别是消化前的1.63倍和2.90倍。果汁、果浆的DPPH自由基、超氧阴离子自由基和羟自由基清除率以及铁还原力均在模拟胃消化1 h和肠消化1 h后达到最大值,随后开始下降并趋于稳定。果浆和果汁的抗氧化能力虽不同,但变化规律类似。研究表明,模拟胃肠消化能促进猕猴桃多酚、黄酮的释放,提高抗氧化活性。     

黄玉米粗类黄酮提取工艺正交试验优化及其体外抗氧化活性

以黄玉米纪元1号为材料,采用单因素试验与三元二次正交试验,考察乙醇体积分数、料液比、浸提温度及浸提时间对粗类黄酮提取量的影响及黄玉米粗类黄酮清除1,1-二苯基-2-苦肼基（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基和•OH的能力。得出最优工艺参数为料液比1∶35.5（g/mL）、69 ℃浸提1.85 h,此条件下粗类黄酮提取量为85.88 mg/g。当粗类黄酮质量浓度为20 mg/mL时,对DPPH自由基和•OH的清除率分别为76.47%和32.62%,分别相当于芦丁标准品（0.1、0.2 mg/mL）清除能力的81%～84%和40%～50%。黄玉米粗类黄酮对DPPH自由基的清除率明显大于对• OH的清除率,且随质量浓度提高,清除率显著提高（P＜0.05）。     

HPLC-DAD-ESI-MS analysis of flavonoid compounds in 5 seedless table grapes grown in Apulian Region

Flavonoids present in skin extracts of red seedless table grape varieties Summer Royal, Autumn Royal, and Crimson, and white seedless varieties Carati and Thompson were analyzed by HPLC-DAD-MS, in 3 y of study (2006 to 2008). The anthocyanins, delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, petunidin-3-O-glucoside (with their corresponding p-coumaroyl derivatives), peonidin-3-O-glucoside, and malvidin-3-O-glucoside (with their corresponding acetyl, caffeoyl, and p-coumaroyl derivatives) were found. In addition the flavonols quercetin-3-O-glucuronide, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside, kaempferol-3-O-galactoside, and the flavan-3-ols procyanidin B1, procyanidin B2, and catechin were also detected. Anthocyanins were the main flavonoids in red grapes ranging from 24 (Crimson) to 500 (Summer Royal) mg/kg fresh weight of grapes; consistent levels of flavonols and flavan-3-ols were also quantified in all varieties. To determine the effective climatic influence on flavonoids content in field conditions, viticultural practices have been developed, that could exclude the effects of direct solar radiation from confounding the assessment of those related to thermal conditions alone. A strong positive correlation was determined between flavonoids and temperature data that seem to be responsible for the difference of these metabolites along the years; furthermore, it has been possible to define a linear relationship (R(2) = 0.6871, P = 0.0057) between thermal amplitude and total flavonoids values in the red grapes. PRACTICAL APPLICATION: Grapes are economically the most important fruit species in the world and approximately 30% of its production is used as fresh fruit. Because of the very important role of flavonoids in food quality as well as their health-promoting properties, and considering that our experiments were performed along 3 consecutive years, gathered results in this research are quite promising to give a useful information on the flavonoid contents and their evolution in 5 seedless table grapes that are widespread in Mediterranean regions but also in California and South America, and are grown in a viticultural climate (Apulia, South Italy) very close to some regions of Spain, Turkey, Tunisia, and Israel.     

槲寄生总黄酮微波提取工艺及其抗氧化活性研究

目的：优化提取槲寄生总黄酮的最佳工艺条件及测定其体外抗氧化活性。方法：以产品中总黄酮的质量分数为指标,正交试验L9(34)对槲寄生的微波辅助萃取工艺参数进行优化,并测定其体外抗氧化活性。结果：槲寄生总黄酮的最佳提取工艺为乙醇溶液体积分数70%、微波萃取功率500W、固液比1:40(g/mL)、萃取温度70℃,提取率达1.88%。其体外清除DPPH 自由基及·OH 的IC50 值分别为0.036mg/mL 和0.572mg/mL。结论：槲寄生总黄酮抗氧化活性明显,且最佳工艺操作简单快捷,适用于工业化大批量提取槲寄生总黄酮。     

Evaluation of antioxidant and inhibitory activities for different subclasses flavonoids on enzymes for rheumatoid arthritis

Antioxidant activities of flavonoids were decreased in the order of flavonols > flavanones > flavones. Inhibitory intensities for hyaluronidase and collagenase reaction differed clearly according to flavonoid subclasses. Kaempferol, quercetin, myricetin, and rutin in flavonols inhibited hyaluronidase reaction specifically, while apigenin, luteolin, baicalin, and baicalein in flavones showed specific inhibition to collagenase reaction. In addition, the flavonoids, except baicalin and catechin, inhibited potently LPS-induced nitrite production in a dose-dependent manner, which might be mainly due to the suppression of inducible nitric oxide (NO) synthase. Quercetin and luteolin showed the strongest inhibitory activities on 15-lipoxygenase (LOX), and quercetin showed relatively potent inhibition on cyclooxygenase-1 (COX-1) reaction. Otherwise, all tested flavonoids possessed the inhibitory activity to COX-2 reaction, and especially luteolin, kaempferol, hesperetin, and naringin showed relatively the potent inhibition on COX-2 reaction. This report elucidated the anti-inflammatory activities, such as the antioxidant property, inhibition of NO production, and inhibition of inflammatory enzymes (hyaluronidase, collagenase, LOX, and COXs) of several subclass flavonoids.     

Phenols,proanthocyanidins, flavones and flavonols in some plant materials and their antioxidant activities

Methanol extracts prepared from five plant materials native to the Mediterranean area, namely olive tree (Olea europaea) leaf, St. John's wort (Hypericum perforatum), hawthorn (Crataegus laevigata), oregano (Origanum vulgare) and laurel leaf (Lauris nobilis), were examined for their phenolic components. Total phenolic content was determined by the Folin–Ciocalteu method. The content of proanthocyanidins in acid-hydrolysed extracts was determined spectrophotometrically. The contents of free flavones (apigenin and luteolin) and flavonols (kaempferol, myricetin and quercetin) were determined by HPLC analysis. The time of hydrolysis of flavones, flavonols and proanthocyanidins was optimised.Antioxidant activities of apigenin, luteolin, kaempferol, myricetin, quercetin and of plant extracts were examined. Antioxidative activities were studied in sunflower oil at 98 °C, by measuring peroxide value, and in an aqueous emulsion system of β-carotene and linoleic acid by measuring the absorbance of the sample. Among flavones and flavonols investigated, only myricetin inhibited oxidation of sunflower oil. All other flavones and flavonols showed pro-oxidative activity. Oppositely, in the emulsion system, only apigenin showed pro-oxidative activity while other flavones and flavonols and plant extracts inhibited oxidation of β-carotene.     

云南栘依黄酮提取及其抗氧化、降血糖活性研究

以云南栘依果为研究对象,采用响应面分析法对超声波辅助酶法提取黄酮进行优化,并对其体外抗氧化和降血糖活性进行测定。结果表明,云南栘依黄酮提取最佳工艺参数为提取温度50℃、复合酶比例(纤维素酶和果胶酶)3:2、提取时间50 min、液料比30 mL/g、乙醇浓度55%、pH4.5,在此条件下云南栘依黄酮得率高达13.10%,与预测值(13.01%)接近。体外抗氧化实验发现云南栘依黄酮清除DPPH自由基、ABTS⁺自由基和羟基自由基的IC₅₀分别为0.04、0.29、0.70 mg/mL,当黄酮浓度分别为0.24、1.40、4.00 mg/mL时,对DPPH自由基、ABTS⁺自由基、羟基自由基清除率分别为93.98%、97.60%、84.26%,同时云南栘依黄酮还具有一定的铁离子还原能力,表明其具有较强的抗氧化能力;体外降血糖实验发现云南栘依黄酮抑制α-葡萄糖苷酶、α-淀粉酶的IC₅₀分别为0.86、0.37 mg/mL,当黄酮浓度为12.0、5.0 mg/mL时对α-葡萄糖苷酶、α-淀粉酶的抑制率分别为...     

不同提取条件对草莓果实抗氧化物质和抗氧化活性的影响

以草莓栽培品种“丰香”(Fragaria ananassa Toyonaka,)绿熟阶段的果实为试材,研究提取试剂、温度、时间对草莓果实抗氧化物质和抗氧化活性的影响。结果表明,甲醇-水-盐酸(体积比80:19.9:0.1)提取物中总酚、类黄酮、抗坏血酸,DPPH自由基清除能力和铁还原氧化能力显著高于甲醇、乙醇、甲醇-乙醇-丙酮体积比(1:1:1)和水的提取物。然而,抗氧化物质提取的最佳条件(60℃,480min)与获得最高抗氧化活性的提取条件(25℃,120min)并不一致,说明抗氧化物质含量的高低并不总是草莓果实提取物抗氧化活性强弱的指示剂。综合抗氧化物质的提取量以及提取物的抗氧化活性,甲醇-水-盐酸(体积比 80:19.9:0.1)在25℃进行120min草莓果实抗氧化物质的提取更为适合。     

Plackett-Burnman联合响应面法优化黑果枸杞黄酮提取工艺及抗氧化性研究

Plackett-Burnman（PB）联合响应面法优化黑果枸杞黄酮提取工艺并评价其抗氧化性。依次通过PB实验设计、最陡爬坡实验设计研究了5种影响因素对提取率的影响,确定了显著性影响因素及响应面中心,采用Box-Behnken（BB）实验设计优化了提取工艺;采用FRAP法及ABTS、DPPH法评价了黑果枸杞黄酮的抗氧化性,并与抗坏血酸进行了平行比较。结果表明,最佳提取工艺参数为:51%乙醇（体积分数）与原料之比为30:1（mL/g）,62 ℃、240 W超声辅助提取42 min,提取率可达42.0974 mg/g（原料）,与理论预测值的相对标准偏差为3.24%;FRAP法及ABTS、DPPH法均表明,黑果枸杞总黄酮还原力强于抗坏血酸,其对ABTS、DPPH自由基清除的IC₅₀分别为0.0252、0.0272 mg/mL,均较抗坏血酸强,且二者抗氧化性均与浓度呈量效关系,为开发黑果枸杞资源、拉长其产业链提供了一定的理论基础。     

蜂胶提取物抗氧化稳定性研究

研究蜂胶中总黄酮的最佳提取条件及不同因素对蜂胶提取物抗氧化稳定性的影响。以乙醇体积分数、提取时间、温度、料液比为主要影响因素,通过L9(34)正交试验,确定最佳提取条件。测定蜂胶提取物在不同的酸碱度、温度、金属离子、光照条件下对羟自由基(.OH)的清除率,分析其抗氧化稳定性。结果表明:在乙醇体积分数80%、温度80℃、提取时间2h、料液比1:10的条件下总黄酮提取率最高。蜂胶提取物对.OH有良好的清除作用。金属离子(Na+、K+、Ca2+)及微酸性条件对蜂胶提取物的抗氧化稳定性影响较小,但强酸强碱、光照、加热的条件对其抗氧化稳定性影响较大。     

富黄酮洋葱酒中黄酮类化合物稳定性研究

目的研究不同因素对洋葱酒中总黄酮化合物的影响。方法以富黄酮洋葱为试验材料,分别测定温度、p H、氧化剂、还原剂、常用的食品添加剂及金属离子对洋葱发酵酒的黄酮含量影响。结果低温对洋葱黄酮影响不大,升高温度可能导致黄酮分解;p H对黄酮影响较大,应尽可能在酸性范围内贮存富黄酮洋葱酒;洋葱黄酮对氧化还原剂较稳定,具有良好的抗氧化能力,但还原剂可能导致黄酮含量减小,应避免接触;在不同浓度的食品添加剂中,黄酮含量较稳定,可以添加常见添加剂调整富黄酮洋葱酒风味;金属离子对其影响较大。结论本研究优化的储藏条件为富黄酮洋葱酒的开发与保存提供了方法与依据。     

Mechanisms by which flavonol aglycones inhibit lipid oxidation better than glycosylated flavonols in comminuted muscle tissue

The effect of glycosylation on the ability of flavonoids to inhibit lipid oxidation in comminuted muscle tissue has not been previously examined. This work examined the ability of quercetin and quercetin-β-d-glucoside to inhibit lipid oxidation in mechanically separated turkey (MST). Quercetin inhibited formation of lipid peroxides and thiobarbituric acid reactive substances (TBARS) more effectively compared to quercetin-β-d-glucoside during frozen storage (p < 0.05). The possible mechanisms that cause glycosylation to decrease inhibition of lipid oxidation were also examined. Hydroxyl radical scavenging activity was similar when comparing quercetin and quercetin-β-d-glucoside, which indicated that the free hydroxyl group in 3 position of C ring in quercetin did not enhance its hydroxyl radical scavenging ability. Since muscle membrane lipids are susceptible to lipid oxidation, the ability of quercetin and quercetin-β-d-glucoside to incorporate into cellular membranes was studied. After adding quercetin and quercetin-β-d-glucoside to minced chicken muscle, flavonol content in the membrane fraction was determined. Around 32% of added quercetin partitioned into the membranes whereas quercetin-β-d-glucoside was not detected in the membranes. Similar trends were observed when each flavonol was added to isolated membranes. These studies suggest that glycosylation of flavonols weakens their ability to inhibit lipid oxidation in muscle tissue partly by decreasing the amount of flavonols in the membrane phase. In order to understand whether metal chelation by flavonols is a likely mechanism involved in the inhibition of lipid oxidation in MST, the role of endogenous metals in promoting lipid oxidation was examined. Addition of the metal chelators ethylenediamine tetraacetic acid (EDTA) and tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) to MST did not inhibit lipid oxidation, which suggests that endogenous metals present in MST were not promoters of lipid oxidation. Hence it seems unlikely that the mechanism of inhibition by flavonols involved metal chelation in the comminuted muscle.     

烟草NtHCT基因对次生代谢物质绿原酸和类黄酮合成的影响

为验证NtHCT是否参与烟草类黄酮的合成,构建pCXSN::NtHCT超量表达载体,利用农杆菌转化法将NtHCT基因转入野生型烟草三生烟,通过HPLC (High Performance Liquid Chromatography高效液相色谱)检测转基因烟草中绿原酸和类黄酮物质的含量变化。结果表明,转基因烟草叶片中绿原酸的含量最高比野生型对照提高了6.3倍,类黄酮成份芦丁和山奈酚芸香苷分别提高了41.6和13.6倍,而生长表型未见明显差异。从而证明NtHCT基因不仅参与调控绿原酸的合成,也正向调控了类黄酮的合成。      

Protection of flavonoids against hypochlorite-induced protein modifications

Plant polyphenols, such as flavonoids, are ubiquitous components of human diet, and have been recognised as efficient radical scavengers and antioxidants. Their protective effects were especially seen in cell-free assays. Whilst in living cells, depending on experimental conditions, polyphenols may manifest both anti- and pro-oxidative activity. In the present study, the effectiveness of fifteen structurally different flavonoids against hypochlorite-mediated changes in in vitro systems, with and without cells, was tested and compared. Quercetin was found to be the best protector against hypochlorite-mediated fluorescein bleaching and BSA thiol groups oxidation, whilst in living cells its effects on hypochlorite-associated cytotoxicity were moderate. Contrary, epigallocatechin gallate, pelargonidin and catechin, with less impressive hypochlorite scavenging activity in cell-free assays, were the most effective against 3-chlorotyrosine formation after hypochlorite treatment. Taken together, special care should be taken when extrapolating the results on antioxidant propensity of food bioactive compounds in vitro to the cellular milieu.     

宁夏枸杞体外抗氧化机理研究

目的：研究宁夏枸杞中主要的4种抗氧化物质（枸杞多糖、黄酮、类胡萝卜素和VC）的抗氧化能力,分析它们对枸杞果实总抗氧化能力的贡献率,探索宁夏枸杞果实的体外抗氧化机理。方法：采用FRAP法、DPPH法、ABTS法和清除羟自由基法4种体外抗氧化方法来评价枸杞鲜果的总抗氧化能力。结果：4种方法测得枸杞黄酮对枸杞果实总抗氧化能力的贡献率均大于96%,VC对枸杞果实总抗氧化能力的贡献率均小于4%,高质量浓度的枸杞多糖（642.7170 mg/L）和类胡萝卜素（109.9280 mg/L）检测不到抗氧化能力。结论：枸杞黄酮的抗氧化能力决定着枸杞果实的体外抗氧化能力。     

Copper-flavonoid complexes in acidic solutions

Summary. Amperometric titration was used to detect complexing of cupric ions by flavonoids in solutions more acid than pH 4.5. Strongest complexing ability was shown by the 3-hydroxy-4-carbonyl system although the 5-hydroxy-4-carbonyl system also complexed with copper in acid solution. the o -diphenolic grouping did not form complexes under the conditions used. Complexing ability was enhanced by the presence of hydroxyl groups in conjugation with the carbonyl group. Quercetin was the only flavonoid tested capable of complexing copper at pH 2.3. the significance of these results to the antioxidant action of flavonoids in fruit juices is discussed.     

Evaluation of the antioxidant and antiproliferative activities of extracted saponins and flavonols from germinated black beans (Phaseolus vulgaris L.)

Flavonoids and saponins from common beans have been widely studied due to their bioactivity. This research evaluated the effect of germination of black beans (Phaseolus vulgaris L.) on the antioxidant capacity and antiproliferative activity against cancer cell lines of saponins and flavonoids extracted from seed coats, cotyledons and sprouts. Principal component analysis was performed to achieve punctual associations between the black bean saponins and flavonoids concentrations to the antioxidant capacity and the antiproliferative activities. Total phenolic content and antioxidant capacity of extracts were higher when obtained from seed coats, mainly from the 3rd germination day. The extracts obtained from seed coats after 3 and 5 germination days inhibited all cancer cell lines proliferation with no cytotoxicity against control cells. Genistein was related with the activity against mammary cancer cells but flavonols and group B saponins were more related with hepatic and colon cancers. Non-glycosilated flavonols were related with antioxidant capacity.