http://www.dietcan.net/docs/Polifenoles%20en%20alimentos%20y%20biodisponibilidad.pdf

Polyphenols: food sources and bioavailability

Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin-Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin-Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology.

https://faculty.missouri.edu/~glaserr/3700s14/Antioxidant-Capacity_jf0502698.pdf

Standardized Methods for the Determination of Antioxidant Capacity and Phenolics in Foods and Dietary Supplements

Flavonoids are a class of secondary plant phenolics with significant antioxidant and chelating properties. In the human diet, they are most concentrated in fruits, vegetables, wines, teas and cocoa. Their cardioprotective effects stem from the ability to inhibit lipid peroxidation, chelate redox-active metals, and attenuate other processes involving reactive oxygen species. Flavonoids occur in foods primarily as glycosides and polymers that are degraded to variable extents in the digestive tract. Although metabolism of these compounds remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. The propensity of a flavonoid to inhibit free-radical mediated events is governed by its chemical structure. Since these compounds are based on the flavan nucleus, the number, positions, and types of substitutions influence radical scavenging and chelating activity. The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships. Despite some inconsistent lines of evidence, several structure-activity relationships are well established in vitro. Multiple hydroxyl groups confer upon the molecule substantial antioxidant, chelating and prooxidant activity. Methoxy groups introduce unfavorable steric effects and increase lipophilicity and membrane partitioning. A double bond and carbonyl function in the heterocycle or polymerization of the nuclear structure increases activity by affording a more stable flavonoid radical through conjugation and electron delocalization. Further investigation of the metabolism of these phytochemicals is justified to extend structure-activity relationships (SAR) to preventive and therapeutic nutritional strategies.

Flavonoid antioxidants: chemistry, metabolism and structure-activity relationships.

Phenolics are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potent antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. In the last few years, the identification and development of phenolic compounds or extracts from different plants has become a major area of health- and medical-related research. This review provides an updated and comprehensive overview on phenolic extraction, purification, analysis and quantification as well as their antioxidant properties. Furthermore, the anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, including recent human intervention studies. Finally, possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.

/pdf/plant-phenolics-extraction-analysis-and-their-antioxidant-2ee2ft7zgl.pdf

Plant phenolics: extraction, analysis and their antioxidant and anticancer properties.

Phenolic compounds in plants and agri-industrial by-products: Antioxidant activity, occurrence, and potential uses

An immortalized B-cell library consisting of cells secreting antibodies to food allergens has been prepared. Peripheral B-cells from seven healthy donors were transformed with Epstein-Barr virus and an immortalized human B-cell library with 2,202 ampoules of multi-clone B-lymphoblastoid cells was obtained. The B-cell library contained various types of B-lymphoblastoid cells secreting antibodies to rice, soybeans, milk, and eggs, and can be used to analyze food allergens. © Rapid Science Ltd. 1998

Preparation of human immortalized B-cells secreting antibodies against food allergens

本研究では，AOAC Internationalの基準に基づき，代表的な抗酸化物質を用いて抗酸化能測定法であるH-ORAC法の室間共同試験を行い，精度の調査を行った．室間共同試験には5種（（＋）-カテキン，Trolox, trans-フェルラ酸，ヘスペレチン，コーヒー酸）の抗酸化物質溶液および粉末を用いた．その結果，RSDrは溶液試料で5.9～13.2％，粉末試料で5.4～10.4％であり，RSDRは溶液試料で16.2～61.4％，粉末試料で16.9～33.2％であった．Trolox検量線の上限濃度である50μMから算出したHorRat値は溶液試料で1.48～5.62，粉末試料で1.54～3.03であり，本室間共同試験によって妥当性が確認されたとは言い難かった．室間再現性低下の要因として，プレートリーダーの特性に起因するウェル間での蛍光強度変化の差異挙げられ，これを低減することがH-ORAC法の室間再現性向上に重要と考えられた．

Interlaboratory study of hydrophilic-oxygen radical absorbance capacity, a method for measuring antioxidant capacity.

The effects of non-dialyzable extracts of several vegetables such as eggplant, green pepper, cabbage, Garland chrysanthemum, kidney beans, cucumber and Welsh onion on the differentiation of U-937 human myeloid leukemia cells were examined. Among the vegetables, the extract of eggplant induced the adhesion of U-937 cells on the culture plate and the morphological change of U-937 cells. A few adhesive and elongated cells was detected in the presence of Garland chrysanthemum. The extracts of cucumber and kidney bean induced only the morphological change of U-937 cells. The evident expression of cell surface antigens of CD11b and CD36 of U-937 cells, which is a marker of differentiation of U-937 cells into monocytes/macrophages, was induced by the extracts of eggplant, kidney bean, cucumber and Welsh onion. These results suggested that the factors which induce the differentiation of U-937 cells into monocytes/macrophages may exist in the non-dialyzable extracts of these vegetables.

Effect of Non-Dialyzable Extracts of Vegetables on the Differentiation of U-937 Human Myeloid Leukemia Cell Line.

野菜に含まれるクロロフィルとカロテノイドをHPLCで同時に測定する条件を検討した.その結果ODSカラムを用い,直線的なグラジエント溶出法で行うことによって良好な分離を得た.注入液には試料のアセトン抽出液をそのまま用いるのが適しており,凍結乾燥試料の場合,1回目の抽出に水を添加することによって色素を完全に抽出できた.遮光し-20℃暗黒下に2週間保存したところ,色素含有量に変化はみられなかった.

Separation and quantification of carotenoids and chlorophylls in vegetables by high-performance liquid chromatography

The effects of ginsenosides and extracts containing melanoidins, which are components of red ginseng, on TNF-α production by rat peritoneal macrophages were examined. The ginsenosides by themselves had no effect on TNF-α production, whereas water extract containing melanoidins, which are Maillard reaction products, stimulated TNF-α production by rat peritoneal macrophages. The total ginsenoside fraction and ginsenoside Rc increased TNF-α production with LPS, as did stimulation by ginsenosides with the water extract. These results suggest that for a healthy immune response it might be better to consume red ginseng itself, which contains a mixture of ginsenosides, polysaccharides and Maillard reaction products, rather than ingesting pure ginseng alone. Red ginseng as an immuno-modulator may be effective in defending against infections or tumors.

Tojiro Tsushida

Papers

Preparation of human immortalized B-cells secreting antibodies against food allergens

Interlaboratory study of hydrophilic-oxygen radical absorbance capacity, a method for measuring antioxidant capacity.

Effect of Non-Dialyzable Extracts of Vegetables on the Differentiation of U-937 Human Myeloid Leukemia Cell Line.

Separation and quantification of carotenoids and chlorophylls in vegetables by high-performance liquid chromatography

Effect of Ginsenosides and Red Ginseng Water Extract on Tumor Necrosis Factor-α Production by Rat Peritoneal Macrophages