油橄榄叶提取物抗氧化及抑菌活性研究

目的 研究油橄榄叶提取物的成分组成和生物活性。方法 采用溶剂浸提法, 以水、50%、70%、90%乙醇(V:V)为溶剂提取油橄榄叶有效成分, 通过傅里叶变换红外光谱法(fourier transform infrared spectrometry, FTIR)、气相色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)等方法对所得提取物的结构特征与组成进行表征分析, 通过DPPH·清除能力、还原力以及滤纸片法分别研究了提取物的抗氧化活性和抑菌活性特征。结果 以90%乙醇为提取剂时, 提取物得率和提取物中总多酚含量最高, 提取物中酚类化合物以2,6-二叔丁基对甲酚和2,4-二叔丁基苯酚为主, 相对含量高达29.34%。提取物具有良好的抗氧化活性, 对灰葡萄孢(Botrytis cinerea)、扩展青霉(Penicillium expansum)表现出明显的抑菌活性。结论 首次发现橄榄叶提取物成分中主要酚类物质是2,6-二叔丁基对甲酚和2,4-二叔丁基苯酚, 提取物具有较强的抗氧化和抑菌活性, 为橄榄叶提取物作为抗氧化剂和抑菌剂提供了理论依据。     

油橄榄叶水提物的有效成分与抗氧化活性研究

油橄榄叶多采用乙醇或甲醇提取,该研究选择水为提取溶剂,比较水提物和醇提物有效成分及抗氧化活性的差异。分别以水、44%乙醇及80%甲醇为溶剂超声提取油橄榄叶,测定总多酚、总黄酮、羟基酪醇及橄榄苦苷含量,比较各提取物对DPPH·、ABTS+·及羟基自由基的清除率与还原力。采用SPSS19.0软件进行主成分分析,评价各成分含量与抗氧化指标的相关性;经降维因子分析,找到代表提取物特征的主成分,根据特征值和方差贡献率计算主成分总分,水提物、乙醇提取物和甲醇提取物的得分分别为249.87、-136.89及-112.98。试验结果表明,油橄榄叶水提物有效成分含量及抗氧化活性显著优于醇提物,具有进一步开发为产品的潜力。     

油橄榄叶有效成分的提取及药理活性的研究进展

油橄榄叶占油橄榄收获总重量的10%,是一种低价、丰富的可再生资源,其提取物具有一定的药理活性,已在保健食品、化妆品及医药领域应用。油橄榄叶提取物具有的修复肝损伤、降糖、保护脑神经作用,使其有望成为降糖、辅助抗乳腺癌和卵巢癌的新药。本文对油橄榄叶中活性成分的提取分离纯化技术、油橄榄叶提取物的药理活性以及油橄榄叶的增值加工进行综述,对油橄榄叶提取物的研究方向及其应用进行了总结,以期更系统完善的发挥油橄榄叶的功效。     

辣椒叶醇提物的体外抗氧化活性

探讨辣椒叶抗氧化作用,采用乙醇提取辣椒叶醇提物,测定其总黄酮含量,并考察该提取物体外总抗氧化活性以及清除超氧阴离子自由基、羟自由基和DPPH自由基的能力。结果表明辣椒叶总黄酮含量为4.2%,醇提取物具有较强的体外抗氧化活性和清除自由基的活性。辣椒叶中含有黄酮以及抗氧化活性成分,具有明显抗氧化作用。     

桉叶抗氧化作用研究进展

桉树是我国重要的造林树种之一,种植面积很大,因而桉叶的生物量非常巨大。开发利用桉叶可提高桉树种植的经济效益,并能保护环境,具有重要意义。桉叶中具有多种生物活性成分,本文综述了国内外多年来对桉叶抗氧化成分及抗氧化活性的研究进展,系统地介绍了桉叶抗氧化作用的相关研究、开发和利用的情况及展望,旨在为桉叶抗氧化活性物质综合利用的相关研究提供参考。      

不同月份“广林9号”桉叶粗提物总酚含量与抗氧化活性研究

为了探索桉叶中酚类化合物的积累规律、开发桉叶保健食品,对不同月份桉叶提取物进行了总酚含量测定,同时采用DPPH自由基清除能力、ABTS自由基清除能力、还原能力等抗氧化评价方法,对不同月份桉叶提取物抗氧化活性也进行了评价。结果表明:不同月份总酚含量差异显著(p<0.05),10月份含量最高,为桉叶的最佳采收期;不同月份桉叶的抗氧化活性存在差异显著(p<0.01),其中10月份抗氧化活性最强。桉叶的抗氧化活性主要与其中的酚类物质有关。      

核桃叶抗氧化作用的研究

对核桃叶中抗氧化物质的提取、性能及有效成分进行了较系统的研究。结果表明;核桃叶的乙醇、丙酮1水提取物均有很强的抗氧化作用,其中以丙酮提取物抗氧化作用最强;提取物浓度达0．10％时的抗氧化活性超过0．02％BHT;核桃叶提取物的抗氧化有效成分主要是单宁、黄酮及萜类化合物。     

檀香叶提取物抗氧化及抗菌活性初步研究

研究檀香(Sandalwood)叶不同溶剂提取物的抗氧化及抗菌活性,为檀香叶资源开发利用提供依据。采用4种不同溶剂提取檀香叶中抗氧化、抗菌活性成分;采用清除DPPH自由基方法测定抗氧化活性,采用平板打孔法测定抗菌活性。结果表明:檀香叶80%乙醇、水、乙酸乙酯提取物可以清除DPPH自由基;80%乙醇提取物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌有抗菌作用,但对霉菌、啤酒酵母没有抑菌作用。乙醇提取物经不同温度、不同光照时间处理后,其抗氧化、抗菌活性较稳定。乙醇提取物经不同pH处理后,抗氧化物质在pH6～8范围内稳定,抗菌物质在pH3～7范围内稳定,碱性条件下不稳定。檀香叶乙醇提取物化学成分标识结果表明:檀香叶乙醇提取物中含有多糖、鞣质、黄酮类、酚类物、有机酸以及氨基酸、多肽、蛋白质等成分。结论:80%乙醇、水、乙酸乙酯提取物具有抗氧化活性,其中,80%乙醇提取物抗氧化活性最好。只有80%乙醇提取物具有抗菌活性。     

檀香叶提取物抗氧化及抗菌活性初步研究

研究檀香(Sandalwood)叶不同溶剂提取物的抗氧化及抗菌活性,为檀香叶资源开发利用提供依据。采用4种不同溶剂提取檀香叶中抗氧化、抗菌活性成分;采用清除DPPH自由基方法测定抗氧化活性,采用平板打孔法测定抗菌活性。结果表明:檀香叶80%乙醇、水、乙酸乙酯提取物可以清除DPPH自由基;80%乙醇提取物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌有抗菌作用,但对霉菌、啤酒酵母没有抑菌作用。乙醇提取物经不同温度、不同光照时间处理后,其抗氧化、抗菌活性较稳定。乙醇提取物经不同pH处理后,抗氧化物质在pH6～8范围内稳定,抗菌物质在pH3～7范围内稳定,碱性条件下不稳定。檀香叶乙醇提取物化学成分标识结果表明:檀香叶乙醇提取物中含有多糖、鞣质、黄酮类、酚类物、有机酸以及氨基酸、多肽、蛋白质等成分。结论:80%乙醇、水、乙酸乙酯提取物具有抗氧化活性,其中,80%乙醇提取物抗氧化活性最好。只有80%乙醇提取物具有抗菌活性。      

辣木叶提取物的制备及抗氧化活性

采用16 种提取方法制备辣木叶提取物,考察不同提取方法对辣木叶蛋白、糖类、多酚类物质提取率和抗氧化剂溶出率的影响。采用乙酸乙酯萃取辣木叶提取物,研究水相中蛋白（水解蛋白）、糖类和乙酸乙酯相中多酚类物质相互作用对辣木叶提取物抗氧化活性的影响。结果表明：采用酶法以及酶法耦合乙醇提取法可以制备蛋白（水解蛋白）、糖类和多酚类物质含量高且抗氧化活性强的辣木叶提取物。采用Ns37071蛋白酶、胰酶时,所得辣木叶提取物蛋白、糖类、多酚类物质提取率最高,抗氧化活性最强。蛋白（水解蛋白）和糖类物质对辣木叶提取物抗氧化活性的贡献大于多酚类物质,是辣木叶提取物发挥抗氧化活性的重要物质基础。此外,辣木叶提取物中蛋白（水解蛋白）、糖类、多酚类物质存在协同增效或拮抗作用。     

Antioxidant activity and phenolic contents of Olea europaea L. leaves sprayed with different copper formulations

Olive trees (Olea europaea L. Cv. Cobrançosa) from the northeast of Portugal were sprayed with three different copper formulations [bordeaux mixture (copper sulphate + calcium hydroxide − 20% Cu), copper hydroxide (40% Cu) and copper oxychloride (50% Cu)] to control olive fungal diseases. The residues of copper in olive leaves, harvested at different times, were evaluated by atomic absorption spectrometry. At all the collection times, treated olive leaves had significantly higher copper contents, compared to the control. The different copper amounts in pesticide formulations lowered the leaves contents in total phenols and hence their antioxidant properties. Olive leaves sprayed with copper oxychloride possessed the highest copper levels and the lowest content in phenols, which influenced its antioxidant activity (higher EC₅₀ values for reducing power, scavenging effect on DPPH radicals and inhibition of erythrocyte hemolysis). Leaves without copper residues proved to be a good natural source of antioxidants, giving values comparable to the reference compounds.     

Hydrophilic and Lipophilic Antioxidant Activity in Different Leaves of Three Lettuce Varieties

Three different Lactuca sativa L. varieties (Iceberg, Romaine and Baby head) were analysed in order to determine differences in the antioxidant activity, both hydrophilic and lipophilic, and in the total phenolic content of different leaves (stem, inner, medium and outermost leaves). Romaine showed the highest level of hydrophilic and lipophilic antioxidant activity, and its phenolic content was also higher than that of Iceberg and Baby head. According to leaf position, lipophilic antioxidant activity increased sharply from stem to outermost leaves, suggesting a protective role for the lipophilic antioxidant in mature or light-exposed leaves, while hydrophilic antioxidant activity shows a non-specific distribution. The phenolic content also increased in Romaine from stem to outermost leaves, although no significant changes were observed in Iceberg or Baby head lettuces in this respect.     

Antioxidant activity of coffee brews

The total antioxidant activity of coffee beverages was measured with stabilized radical EPR spectroscopy. Depending on which stabilized radical is used, Fremy's salt (potassium nitrosodisulphonate) or 2,2,6,6-tetramethyl-1-piperidin-1-oxyl (TEMPO) values can differ significantly. For the determination of antioxidant activity of Maillard reaction products in coffee, TEMPO appears to be the better radical marker. Thus the contribution of both main antioxidant active compounds (polyphenols, melanoidins) whose ratio varies with roasting conditions could be estimated. During storage experiments of coffees brews changes in antioxidant action are found to be time dependent. The content of chlorogenic acids increased significantly at higher storage temperatures, probably caused by a release from polymer structures. Additional antioxidant capacity of coffee melanoidins seems to be strongly influenced by atmospheric oxygen. The higher roasted sample is less vulnerable than medium or light roasted coffee. Investigations with model systems showed that among all coffee constituents the carbohydrates are mainly responsible for the formation of oxygen scavenging substances.     

Phenolic Contents and Antioxidant Activities of Date Palm (Phoenix dactylifera L.) Leaves

The antioxidant capacity and phenolic content of three varieties of Phoenix dactylifera leaves, namely Deglet Nour, Medjhoul, and Barhee, were studied. The antioxidant activities of extracts of different leaf varieties obtained with solvents of different polarity were investigated using assays of 2, 2-diphenyl-2-picrymhydrasyl hydrate radical-scavenging activity, total phenolics and flavonoids amount, condensed tannins, reducing power, and total antioxidant capacity. The results showed that all the extracts exhibited antioxidant and radical-scavenging activities at different magnitudes and potency. The decreasing order of antioxidant and radical-scavenging activities among the extracts assayed were found to be methanol (MeOH) fraction > ethyl acetate fraction > hexane fraction > water extract. Correlation analysis indicated that there is a linear relationship between antioxidant potency, free radical-scavenging ability, and the content of phenolic and flavonoids compounds of Phoenix dactylifera leaf extracts. These results showed that Phoenix dactylifera leaf extracts are a valuable natural antioxidant, which can be applied in both healthy medicine and food industry and biotechnology.     

3种食品天然植物包材的抗氧化活性成分对比研究

The antioxidant components and antioxidant functions of three commonly used natural food packaging materials, including Indocalamus leaves, reed leaves and lotus leaves were investigated. The active components were extracted by ultrasonic extraction. The contents of total phenols and total flavonoids, the hydroxyl radical scavenging activity, superoxide radicals scavenging activity, DPPH free radical scavenging activity, ABTS+ free radical scavenging activity, total antioxidant activity and reducing power of plant extracts were determined. The relation between antioxidant functions and antioxidant active ingredients was tested. The results indicated that the contents of total phenols and total flavonoids in lotus leave were higher than these of Indocalamus leaves and reed leaves, and the difference was significant (P<0.05). The total phenol content of three plants was extremely significantly correlated with the hydroxyl radical scavenging activity, superoxide radicals scavenging activity, DPPH radical scavenging activity, ABTS+ scavenging activity, total antioxidant and reducing power (P<0.01). The total flavonoid content was extremely significantly correlated with the total antioxidant and reducing power (P<0.01), and significantly correlated with the ABTS+ free radical scavenging ability (P<0.05). The content of isoquercitrin was high in Indocalamus leaves, and reed leaves and the content of luteolin-6-c-glucoside was high in reed leaves and lotus leaves. These ingredients contained the 4-carbonyl group, 2, 3-double bond and o-dihydroxy group of B ring. In summary, Indocalamus leaf, reed leaf and lotus leaf contained many kinds of polyphenols, which have strong free radicals scavenging activity and other antioxidant function.     

Antioxidant properties of various solvent extracts from wild ginseng leaves

Water, methanol and ethanol extracts of freeze-dried leaves of wild ginseng were examined for their antioxidant properties. All leaf extracts were capable of free radicals scavenging activity. Among solvent extracts of wild ginseng leaves, ethanol extract showed the highest DPPH, hydroxyl radical scavenging and ferrous ion chelating activity. Otherwise, the highest superoxide radical scavenging activity was found in water extract followed by ethanol and methanol extracts of wild ginseng leaves. Ethanol extracts contained more phenolics (2333.2 mg/100 g) and flavonoids (1199.1 mg/100 g) than other extracts. These differences in concentrations of key antioxidants among various solvent extracts seemed to be responsible for their differences in antioxidant activities. When various solvent extracts were hydrolysed by acid, two aglycons of flavonoid, quercetin and kaempferol, were detected. According to the results obtained from this study, wild ginseng leaves showed marked antioxidant activities due to their abundant antioxidants.     

Isolation and Identification of Antioxidant Compounds from Gynura Bicolor Stems and Leaves

The antioxidant compounds in the stems and leaves of Gynura bicolor were studied. 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were employed to evaluate antioxidant capacity. By solvent extraction and Sephadex LH-20 column chromatography in sequence, ethanol extracts of Gynura bicolor stems and leaves were fractionated to obtain their active fractions, which were further separated to obtain 12 compounds: 1–8 from stems, and four, 8–12, from leaves. Their structures were elucidated on the basis of spectroscopic data (nuclear magnetic resonance and mass spectrometry). Among these substances, compounds 1, 2, 3, 4, and 8 with significant antioxidant activity were determined to be responsible active components for stems, and compounds 4, 8, and 12 for leaves.     

Antioxidant capacity of extracts from wild and crop plants of the Mediterranean region

ABSTRACT:  There is an increasing demand for natural antioxidants to replace synthetic additives in the food industry. The present work examines the potential of some wild and cultivated plants from the Mediterranean region as sources of natural antioxidants. Samples of different organs and tissues from each of these species were extracted with aqueous and organic solvents and analyzed for their total hydrosoluble and lipid-soluble antioxidant capacity, measured by the phosphomolybdenum method, and for their content in tocopherols. Our results demonstrate that there is more than a 1000-fold difference among total antioxidants in various plant sources. The highest level of water-soluble antioxidant capacity was found in fruit peel and leaf samples, while seeds presented the highest levels of lipid-soluble antioxidant capacity. Tocopherols were more abundant in leaf samples. Holm oak and olive tree leaves showed the highest yields of α-tocopherol. These Mediterranean plant species could be used as a very good source of both water-soluble and lipid-soluble antioxidants, particularly α-tocopherol.