Antioxidant activity of sage extracts in rapeseed oil irradiated with UV-rays

The antioxidant activities of sage acetone oleoresin and its methanol-water fractions were tested in rapeseed oil at 0.1% concentrations and 80 degrees C temperature after irradiation with UV-rays (exposition 0.5 h). It was determined that even little doses of UV irradiation induce oxidation process in rapeseed oil samples both with additives and without them. The antioxidant activity of a synthetic antioxidant BHT was much lower than that of the sage fractions at 80 degrees C and forced air oven conditions. This finding proves the advantage of sage extracts in comparison with BHT at high temperatures. It was also found that methanol-water fraction separated from acetone oleoresin had the highest antioxidant activity in terms of the formation of primary and secondary oxidation products. Oil sample with this additive had the highest protection factor (PF = 4.53) when the oil was not irradiated with UV rays. The data obtained showed that all sage extracts had very strong antioxidant activity (PF > 3).     

Preliminary screening of antioxidant activity of some plant extracts in rapeseed oil

The antioxidant activity (AA) of acetone extracts of sage (Salvia officinalis L.), sweet grass (Hierocloë odorata Wahlnb.), sea buckthorn leaves (Hipophaë rhamnoı̈des L.), costmary (Balsamita major Desf., syn. Chrysanthemum balsamita L.), Roman camomile (Anthemis nobilis L.), and tansy (Tanacetum vulgare L.) were tested in refined, bleached and deodorised rapeseed oil at 40°C. The concentrations of the extracts added were in the range from 0.02 to 0.20% (w/w). The rate of oxidation was assessed by the measurement of peroxide value (PV) and calculation of such characteristics as induction period (IP), when PV reaches 20 meq kg⁻¹, protection factor (PF), which is the ratio of IP of the sample with additive with IP of the sample without additive, and AA (the ratio of IP increase of the sample with extract with the IP increase of the sample with butylated hydroxytoluene). Sage and sweet grass extracts were found to be most effective in stabilising rapeseed oil, followed by tansy, Roman camomile, costmary and sea buckthorn in a decreasing order. The IP of rapeseed oil increased with extract concentration. AA's of the extracts added at different concentrations were the following: sage, sweet grass (0.05, 0.1 and 0.2%) and tansy (0.2%) — very high, (PF>3); tansy and Roman camomile (0.1%) — medium (PF=2–2.5), tansy (0.05%), Roman camomile (0.02 and 0.05%) and sea buckthorn (0.1 and 0.2%) — low (PF=1.5–2.0), tansy (0.02%) — very low (PF=1.0–1.5). The extracts of sea buckthorn (0.02 and 0.05%) slightly increased the formation of peroxides in rapeseed oil as compared with pure oil.     

Antioxidant activity of extracts from Gevuina avellana and Rosa rubiginosa defatted seeds

Chilean hazelnuts (Gevuina avellana Mol) and mosqueta rose (Rosa aff. Rubiginosa L.) meals were extracted with methanol, ethanol, acidified water, acetone, butanol, diethyl ether and ethyl acetate. Ethanol and methanol extracted the highest amount of soluble substances from both seed meals. The highest concentration of total polyphenols was found in the ethanolic extracts, although that of acetone from R. rubiginosa presented similar values. The antioxidant activity of the extracts evaluated by the β-carotene assay and with as hydrogen radical scavenging ability showed that the activity of the butanol and methanol extracts from G. avellana was comparable to those of synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The 2,2,-diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging activity of the G. avellana methanol, ethanol and water extracts was 2–3 times lower than those of BHT and BHA, respectively. The activity of R. rubiginosa extracts ranged from that of BHT for the water extracts to 80% inhibition in respect to control achieved with the ethanol extracts.     

石榴皮提取物的抗氧化作用研究

分别以水、甲醇、丙酮和乙酸乙酯为溶剂,对石榴皮中的多酚进行了提取,得到4种提取物。采用油脂过氧化值(POV)法和二苯三硝基苯肼(DPPH)自由基法研究了提取物的抗氧化活性。结果显示,4种提取物均具有抗油脂过氧化和清除DPPH自由基的能力,其抗氧化活性随添加量的增加而增加。4种提取物中,丙酮提取物的抗油脂过氧化作用最大,其次为水提取物和甲醇提取物,乙酸乙酯提取物的抗油脂过氧化作用最小。当丙酮提取物添加量为猪油质量的0.1%时,其抗油脂过氧化活性接近添加量为0.02%茶多酚或BHT。4种提取物对DPPH自由基的清除能力大小顺序依次为:水提取物、丙酮提取物、甲醇提取物和乙酸乙酯提取物。浓度为0.0175 mg/mL的水提取物对DPPH自由基的清除率高达85.2%,高于BHT,但略低于茶多酚。石榴皮多酚是一种有效的天然抗氧化剂。     

蜂胶提取物的抗氧化活性研究

以菜籽油和猪油为实验油,采用schall烘箱法测定蜂胶及其乙醇提取物、超临界CO2提取物和CO2残渣醇提物的抗氧化活性,并与其他通用抗氧化剂比较。结果表明:总黄酮浓度0.01%以上的蜂胶提取物均能显著延长油脂氧化诱导期,是高效的油脂抗氧化剂;黄酮类化合物仍是各蜂胶提取物中主要含量成分和主要抗氧化活性成分之一,且随总黄酮浓度0.005%以上一定范围与其整体抗氧化活性呈现量效关系;在相同添加量0.02%(蜂胶提取物均以总黄酮计)和恒温60℃条件下,各抗氧化剂抗氧化效果按强弱顺序排列为:菜籽油中,TBHQ>蜂胶超临界CO2提取物>蜂胶CO2残渣醇提物≥蜂胶乙醇提取物>VE>甘氨酸>蜂胶>BHT;猪油中,TBHQ>蜂胶CO2残渣醇提物≥蜂胶乙醇提取物≥BHT>甘氨酸>蜂胶>蜂胶超临界CO2提取物>VE。本试验结果可望为各蜂胶提取物将来被用作含油脂食品的天然抗氧化剂提供一定的实验数据。     

Antioxidant activities of barley seeds extracts

The antioxidant activities of different polarity solvents extracts from barley were evaluated by various antioxidant assays, including reducing power, free radical scavenging and lipid oxidation inhibition. Those various antioxidant activities were compared to standard antioxidants, butylated hydroxyluene (BHT) and ascorbic acid (Vit. C). The properties of the extracting solvents significantly affected the total phenolics, proanthocyanidins and antioxidant activities of barley extract. The highest contents of total phenolics and proanthocyanidins were obtained from extraction with 70% acetone. For three different solvent extracts, the antioxidant activities were in this order: 70% acetone extract > 70% ethanol extract ? 70% methanol extract. Reducing powers of three extracts and their scavenging effects on 2, 2-diphenyl-1-picrylhydrazyl radicals were effective at amount of 200 μg. The 70% acetone extract of barley exhibited high antioxidant activity in linoleic acid system, which was not significantly (P < 0.05) different from BHT during the incubation time.     

Rapid screening of antioxidant activity of sage (Salvia officinalis L.) extracts obtained by supercritical carbon dioxide at different extraction conditions

Sage herb (Salvia officinalis L.) was extracted at supercritical fluid extraction (SFE) conditions with carbon dioxide at different parameters and the extracts tested on their antioxidant activity (AA). SFE of sage herb at 35 MPa pressure was found to be an effective method to obtain pure extracts. The yields of the extracts were substantially increased by using 1% of entrainer solvent ethanol. The fractionation of sage extract was a complex procedure in terms of extract distribution between separators operating at various pressure and temperature conditions. It was also proved by testing the AA of the extracts in rapeseed oil. The effect of the extracts on the rapeseed oil weight gain varied in a wide range (from ‘very low’ to ‘high’) depending on the fractionation conditions. Preliminary results showed that to obtain more effective antioxidant fractions separation steps should be started at 10 MPa lower pressure than that used for the extraction.     

Antioxidant activity of sweetgrass (Hierochloë odorata Wahlnb.) extract in lard and rapeseed oil emulsions

The antioxidant activities of sweetgrass (Hierochlo? odorata) and sage (Salvia officinalis) extracts were studied in emulsions of lard and rapeseed oil using soy lecithin as an emulsifier, and addition of cupric acetate as an oxidation catalyst. The antioxidant activity was about the same in the two substrates. The stability against autoxidation was substantially increased by both sweetgrass and sage extracts and their combination. The stability was particularly high, if citric acid and/or ascorbyl palmitate were added to plant extracts.     

Antioxidant activity of sweetgrass (Hierochloë odorata Wahlnb.) extract in lard and rapeseed oil emulsions

The antioxidant activities of sweetgrass (Hierochloë odorata) and sage (Salvia officinalis) extracts were studied in emulsions of lard and rapeseed oil using soy lecithin as an emulsifier, and addition of cupric acetate as an oxidation catalyst. The antioxidant activity was about the same in the two substrates. The stability against autoxidation was substantially increased by both sweetgrass and sage extracts and their combination. The stability was particularly high, if citric acid and/or ascorbyl palmitate were added to plant extracts.     

Rapid screening of antioxidant activity of sage (Salvia officinalis L.) extracts obtained by supercritical carbon dioxide at different extraction conditions.

Sage herb (Salvia officinalis L.) was extracted at supercritical fluid extraction (SFE) conditions with carbon dioxide at different parameters and the extracts tested on their antioxidant activity (AA). SFE of sage herb at 35 MPa pressure was found to be an effective method to obtain pure extracts. The yields of the extracts were substantially increased by using 1% of entrainer solvent ethanol. The fractionation of sage extract was a complex procedure in terms of extract distribution between separators operating at various pressure and temperature conditions. It was also proved by testing the AA of the extracts in rapeseed oil. The effect of the extracts on the rapeseed oil weight gain varied in a wide range (from 'very low' to 'high') depending on the fractionation conditions. Preliminary results showed that to obtain more effective antioxidant fractions separation steps should be started at 10 MPa lower pressure than that used for the extraction.     

Effects of blackcurrant seeds and rosemary extracts on oxidative stability of bulk and emulsified lipid substrates

The effects of blackcurrant seeds extract and commercially available rosemary extracts on rapeseed oil and rapeseed oil triacylglycerol oxidative stability were evaluated. The antioxidant activity of plant extracts was investigated, both in bulk and emulsified lipid substrates, and compared with those of α-tocopherol and BHT. The investigation showed that blackcurrant seeds and rosemary extracts are the source of active antioxidants and are appropriate for food lipid stabilization. The extracts performed better in stripped substrates as they may interfere with native tocopherols present in rapeseed oil and show different activity according to the presence of water. α-Tocopherol, a 200 ppm, was inactive in bulk and emulsified rapeseed oil but was an effective antioxidant in triacylglycerols. BHT showed the best performance of all used additives in emulsified substrates.     

Oxidative stability of palm‐ and soybean‐based medium‐ and long‐chain triacylglycerol (MLCT) oil blends

BACKGROUND: Medium‐ and long‐chain triacylglyerols (MLCT) enzymatically esterified using Lipozyme RM IM lipase has very low oxidative stability as it does not contain any antioxidants. The aim of this work was to study the ability of various antioxidants to increase the oxidative stability of palm‐ and soybean‐based MLCT blends which assist to bring up the oxidative stability of both MLCT blends. In this study, the effectiveness of rosemary extracts, sage extracts, tert‐butylhydroquinone (TBHQ) and mixtures of tert‐butyl‐4‐hydroxyanisole (BHA) and tert‐butyl‐p‐hydroxytoluene (BHT) in protecting against oxidation of various MLCT blends was investigated. RESULTS: Blending of MLCT oil with either palm olein or soybean oil improved its smoke point values and oxidative stability. TBHQ addition to both palm‐ and soybean‐based MLCT blends increased oxidative stability. Combination of BHA and BHT showed no significant improvement (P > 0.05) in ability to protect blends from oxidation compared to natural antioxidants such as sage or rosemary extracts. CONCLUSION: Blended oils with 500 g kg^?1 MLCT and 500 g kg^?1 palm olein (MP5) were the most suitable for use at high temperature based on the fatty acid composition of the MLCT blends, which subsequently had an effect on thermal oxidative stability. In general, addition of either natural or synthetic antioxidant assisted in improving the antioxidative strength of both MLCT blends. MLCT blends with added TBHQ showed the highest thermal oxidative stability among the antioxidants used. Copyright © 2008 Society of Chemical Industry     

Antioxidant and radical-scavenging carbazole alkaloids from the oleoresin of curry leaf (Murraya koenigii Spreng.)

Oleoresin of curry leaves (Murraya koenigii Spreng.), obtained using acetone, was evaluated for its antioxidant activity using a β-carotene–linoleic acid model system along with the other extracts obtained using methanol, water and volatile oil. The oleoresin showed maximum activity of 83.2% at 100 ppm among all other extractives in comparison to a synthetic antioxidant, namely, butylated hydroxy anisole which exhibited 90.2% activity at the same concentration. The methanol and water extracts showed activities of 16.7% and 11.3%, respectively, at the same concentration. The volatile oil showed negligible (<10%) activity at 100 ppm concentration. Therefore, the oleoresin was fractionated on a silica gel column to obtain five compounds. Among the five, two compounds with maximum antioxidant activity were identified by ¹H and ¹³C NMR spectra as mahanimbine and koenigine. Koenigine also showed a high degree of radical-scavenging activity.     

Effect of plant extracts on the oxidative stability of sunflower oil and emulsion

The antioxidative activities of six plant extracts (catnip, hyssop, lemon balm, oregano, sage and thyme) were evaluated in sunflower oil and its 20% oil-in-water emulsion in the dark at 60°C. The oxidation process was followed by measuring the formation of primary (conjugated diene hydroperoxides) and secondary (volatile compounds) oxidation products. Sage extracts (600 and 1200 ppm) effectively inhibited the formation of conjugated dienes and volatile compounds (hexanal and pentanal) in oil and emulsion and showed the highest antioxidative activity compared with 300 ppm BHT. Thyme and lemon balm extracts inhibited hexanal generation more than formation of conjugated dienes in both oil and emulsion. Oregano extract was more active in oil than in emulsion. Catnip and hyssop extracts (600 ppm) showed prooxidative action to sunflower oil at 60°C. These two extracts increased the formation of conjugated dienes compared with the control oil. In emulsions, catnip extract (600 ppm) was active and significantly inhibited the formation of conjugated dienes more than BHT (300 ppm) during additional incubation.     

Phenolic compounds from winemaking waste and its antioxidant activity towards oxidation of rapeseed oil

The effects of extraction parameters on bioactive compound contents of winemaking waste extracts (WWE) and its effect on rapeseed oil oxidative stability were evaluated. Research showed that the total phenols and anthocyanin contents and antioxidant activity (AA) of WWE significantly depended on the extraction parameters. Increasing the temperature (60 °C) and time (5 h) of extraction and an addition of water to ethanol statistically improved the rate of active component extraction. HPLC analysis showed that procyanidin B_2, catechin, gallic acid, γ‐resorcylic acid and p‐coumaric acid were the major phenolic compounds of WWE. Important correlations between total phenolic compounds quantified by HPLC and both DPPH and (ferric reducing antioxidant power) (FRAP) values were found. WWE added to the oil at three different levels clearly slowed down the process of fatty acid oxidation, inhibiting hydroperoxide formation by about 86%, comparable with BHT, while it was more effective than that of α‐tocopherol. When using volatile compound formation as a marker of lipid oxidation, WWE at the level of 2000 ppm were the most effective inhibitors of the decomposition of hydroperoxides. The research showed that the WWE are a rich source of phenolic compounds with powerful antioxidant activities and are suitable for preventing rapeseed oil oxidation.     

ANTIOXIDANT ACTIVITY OF PHENOLIC FRACTIONS OF RAPESEED

Extract of rapeseed in 80% methanol was prepared. Three fractions (I-III) were separated from the extract on a Sephadex LH-20 column using ethanol as the mobile phase. The antioxidant activity of fractions was investigated using a β-carotene-linoleate model system and enhanced chemiluminescence (ECL) and photochemiluminescence (PCL) methods. Scavenging effect on DPPH radical and reducing power of the extract were examined, UV spectra recorded and the content of total phenolics determined. The highest content of total phenolics (176 mg/g) was present in fraction III; the content of total phenolics found in fraction I was the lowest (78.6 mg/g). UV spectra indicated that derivatives of phenolic acids were dominant in all fractions. Results of β-carotene-linoleate model     

大叶紫薇叶提取物抗氧化性能的研究

采用不同溶剂对大叶紫薇叶进行浸泡提取,计算提取率,并用FolinCiocalteu方法测定总酚含量;采用DPPH分析法和FRAP分析法评估了不同溶剂提取物的抗氧化活性,选出抗氧化活性最高的提取物添加到猪肉中,于4℃光照下贮存12d,通过测定贮存期间猪肉的TBARS值、pH值和亨特L、a、b值,评估了提取物抗脂质氧化、防腐保鲜和护色作用,并与BHT、VE、茶多酚比较。结果表明,不同溶剂提取物显示出不同的抗氧化活性,其中甲醇提取物抗氧化活性最高(高于BHT),其提取率和总酚含量也最高。大叶紫薇叶甲醇提取物在生猪肉中具有明显的抗脂质氧化和防腐保鲜的作用,且随着提取物含量的增大,抗氧化的效果增强,有明显的量效关系。     

ANTIOXIDANT ACTIVITY OF PHENOLIC FRACTIONS OF LENTIL (LENS CULINARIS)

Extract of lentil seeds in 80% acetone was prepared. Four fractions (I-IV) were separated on a Sephadex LH-20 column using methanol as the mobile phase. The antioxidant activity of each fraction was investigated in a β-carotenelinoleate model system; UV spectra were recorded and the content of total phenolics determined. Results of β-carotene-linoleate model system indicated that antioxidant activities of separated fractions correlated with their content of total phenolic compounds and were in the order of IV>III>II>I. Fractions III and IV from lentil showed much stronger antioxidant activity than phenolics fractions separated from extracts of several different legumes using Sephadex LH-20 column chromatography. Absorption maxima of UV spectra showed that flavonoids were the main phenolic compounds present in the separated fractions. Results of EI-MS confirmed the presence of epicatechin in fraction III while condensed tannins were detected in fraction IV using TLC.     

天山雪菊不同溶剂提取物的抗氧化活性研究

以天山雪菊为原料,经过超临界二氧化碳萃取后,萃余物又分别采用丙酮、体积分数分别为50%、95%乙醇进行提取,获得不同溶剂提取的4种天山雪菊提取物,比较不同溶剂提取物的抗氧化活性。通过对二苯基苦基苯肼(DPPH)自由基和羟基自由基清除能力的评价,比较各种提取物的抗氧化活性,并对各种提取物中的总多酚和总黄酮的含量进行了分析。结果表明,4种提取物对DPPH自由基均具有较强清除活性,但活性弱于对照品二丁基羟基甲苯(BHT)、水溶性维生素E(Trolox)、α-生育酚和Vc;对羟基自由基的清除能力低于对照品芦丁和BHT。清除DPPH自由基的能力以体积分数为50%乙醇提取物最强,超临界浸膏最弱;清除羟基自由基的活性以体积分数为50%乙醇提取物最强,丙酮提取物最弱。     

Antioxidant activity of extracts obtained by different isolation procedures from some aromatic herbs grown in Lithuania

An increasing demand for natural additives has shifted the attention from synthetic to natural antioxidants. The present work examines the potential of some aromatic herbs grown in Lithuania as a source of natural antioxidants: marjoram (Majorana hortensis Moench), catnip (Nepeta cataria L), oregano (Origanum vulgare L), lavender (Lavandula angustifolia Mill), thyme (Thymus vulgaris L), hyssop (Hyssopus officinalis L), anise hyssop (Lophantus anisatus Benth), and sage (Salvia officinalis L). Dried herb samples were submitted to extraction with supercritical CO₂, acetone or methanol/water and hydrodistillation. Deodorised herb samples (after removal of essential oil) were also extracted with acetone. The antioxidant activity of these extracts, essential oils and dried deodorised aqueous extracts was assessed by the β-carotene bleaching test (diffusion and spectrophotometric methods). The highest yields of extracts were obtained using polar solvents. Thyme and sage acetone oleoresins showed high antioxidant activity in the tests performed and were regarded as the most promising sources. © 1998 SCI.