A review of the antioxidant potential of medicinal plant species

Some researchers suggest that two-thirds of the world's plant species have medicinal value; in particular, many medicinal plants have great antioxidant potential. Antioxidants reduce the oxidative stress in cells and are therefore useful in the treatment of many human diseases, including cancer, cardiovascular diseases and inflammatory diseases. This paper reviews the antioxidant potential of extracts from the stems, roots, bark, leaves, fruits and seeds of several important medicinal species. Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxylanisole (BHA) are currently used as food additives, and many plant species have similar antioxidant potentials as these synthetics. These species include Diospyros abyssinica, Pistacia lentiscus, Geranium sanguineum L., Sargentodoxa cuneata Rehd. Et Wils, Polyalthia cerasoides (Roxb.) Bedd, Crataeva nurvala Buch-Ham., Acacia auriculiformis A. Cunn, Teucrium polium L., Dracocephalum moldavica L., Urtica dioica L., Ficus microcarpa L. fil., Bidens pilosa Linn. Radiata, Leea indica, the Lamiaceae species, Uncaria tomentosa (Willd.) DC, Salvia officinalis L., Momordica Charantia L., Rheum ribes L., and Pelargonium endlicherianum. The literature reveals that these natural antioxidants represent a potentially side effect-free alternative to synthetic antioxidants in the food processing industry and for use in preventive medicine.     

Evaluation of antioxidant activity and total phenolics of selected Czech honeys

Honey serves as a good source of natural antioxidants, which are effective in reducing the risk occurrence of heart disease, cancer, cataracts, different inflammatory processes and immune-system decline. In the fresh selected Czech honey samples originated mainly from the region North Moravia antioxidant activity and total polyphenol content were determined. A total of 40 honey samples (multifloral, lime, rape, raspberry, mixture and honeydew honeys) native to different stations gained in the period from May by August year 2006 were analysed. Total phenolics (TP) content was determined by the modified Folin-Ciocalteau method [TP was expressed as mg of gallic acid equivalent (GA eq.) per kg of honey]. For evaluation of the antioxidant activity (AOA) three different methods were used, the ferric reducing antioxidant power (FRAP) assay, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the 2,2′-azinobis(3-ethylbenzothiazolin)-6-sulfphonate (ABTS) assay. AOA was expressed in mg ascorbic acid equivalent (AA eq.) per kg of honey. The results indicated that TP and AOA in Czech honey varied greatly between the honey kinds, location and time of the harvest. Average TP ranged from 89.9 mg GA eq. kg^-1 in lime honey to 215.2 mg GA eq. kg⁻¹ in honeydew honey. Antioxidant activity determined by the DPPH, ABTS and FRAP methods was lowest in floral honeys. The highest values were obtained for honeydew and mixture honeys. ABTS and FRAP assays have been shown to be the optimal methods for AOA determination in honey. A positive linear correlation between AOA and TP was observed (in FRAP assay R² = 0.852). It indicates that phenolics are one of the main components responsible for antioxidant behaviour of honey. The obtained results support and extend complete knowledge about the content of bioactive phenolics and antioxidant activity in the Czech honeys.     

Influence of malt on the xanthohumol and isoxanthohumol behavior in pale and dark beers: A micro-scale approach

The main objective of this work was to understand which compounds are responsible for the partial inhibition of xanthohumol (XN) thermal isomerization during wort boiling of dark malts. With such purpose, worts from different kinds of malt (pale, caramel and roasted) were chemically characterized (e.g. antioxidant activity, polyphenols and melanoidins contents) and studied by several chromatographic techniques. Molecular exclusion chromatography experiments showed that adsorption of XN to polyvinylpolypyrrolidone is lower for the high molecular weight fractions. It seems likely that this is due to the reaction between XN and coloured substances that changes chemical properties of XN or, at least, results in the formation of complexes that have different chemical properties. This leads to an inhibition of XN isomerization observed in this work. It was also verified that the melanoidins content was significantly higher in the higher molecular weight fractions, suggesting that probably these compounds are the main responsible for the XN isomerization inhibiting effect.     

震动膜过滤法分离纯化葡萄籽原花青素

目的：研究应用震动膜过滤技术对葡萄籽提取物中原花青素的分离纯化效果。方法：应用不同膜孔径的薄膜对葡萄籽提取物进行微滤、浓缩等操作,以通量变化为指标考察膜的稳定性,称量法考察滤液的杂质去除情况,并以Folin-Ciocalteau法测定原花青素的含量。结果：震动膜过滤技术可以有效去除葡萄籽提取物中的大分子杂质,提高原花青素的纯度;同时配合浓缩膜,可使分离浓缩连续进行,工序少、效率高、成本低。结论：震动薄膜过滤技术可用于葡萄籽提取物中原花青素的分离、浓缩工艺。     

Bioprospecting traditional Pakistani medicinal plants for potent antioxidants

Antioxidant potential of four methanol extracts from three selected plant species, namely Salvia nubicola (Lamiaceae), Acer oblongifolium (Aceraceae) and Hedera nepalensis (Araliaceae) was measured using assays in aqueous and lipid systems. Antioxidant activities were investigated in aqueous systems by using DPPH radical-scavenging assay, ABTS radical-scavenging assay and DNA protection assay, while antioxidant activity in a lipid system was determined by using the thiobarbituric acid-reactive substances (TBARS) assay. Additionally, the Folin-Ciocalteu method was used to measure total phenolic content. Methanol extracts of leaves and flowers of S. nubicola showed the highest Trolox equivalent (TE) values in the case of the DPPH assay, 2484 ± 4.9 mmol TE/g extract, as well as total phenolic content, 139 ± 0.2 mg gallic acid equivalents/g extract. Three fractions (A-C) of the methanol extract of S. nubicola leaves and flowers were produced by semi-preparative HPLC. Fraction B was found to be the most active in the DPPH radical-scavenging assay and had the highest total phenol content. HPLC-DAD and LC-MS revealed rosmarinic acid in S. nubicola extracts and chlorogenic acid and rutin in H. nepalensis extracts as the main phenolic antioxidants.     

Antioxidant properties of Phyllanthus amarus extracts as affected by different drying methods

The total phenolic content (TPC) and antioxidant activity of fresh and dried Phyllanthus amarus plant materials were evaluated using the Folin-Ciocalteau method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) assays. Different drying treatments led to significant reduction (P<0.05) in antioxidant properties of P. amarus methanolic extracts, with microwave drying causing the highest decrease in TPC and antioxidant activity exhibited by the reduction in both radical scavenging activity and FRAP. On the other hand, boiling water extracts appeared to exhibit significantly stronger antioxidant potentials (P<0.05) even in dried plant materials due to greater solubility of compounds, breakdown of cellular constituents as well as hydrolysis of tannins. Its strong free radical scavenging activity suggests that it has great potential in the food industry as functional food ingredient.     

不同软包装材料对葡萄酒总酚含量的影响

通过对温度37℃,相对湿度50%条件下,不同软包装材料包装的红葡萄酒进行贮藏试验,采用福林-酚比色法测定此条件下葡萄酒中总酚含量的变化。研究分析不同透氧率包装材料对红葡萄酒氧化的影响特性,进一步对氧化速率进行分析,并得出基于总酚含量的葡萄酒货架寿命预测模型。     

葡萄籽提取物中原花青素的测定

用高效液相和Folln—Ciocalteau相结合的方法分析了葡萄籽提取物中原花青素的百分含量。此方法能够弥补Bate—Smith法和Porter法只能测定原花青素相对含量的缺陷。分析结果显示：葡萄籽提取物中原花青素的含量为77．4％。