RESUMEN
In the United States, commercially available foods, including cocoa and chocolate, are being marketed with statements referring to the level of antioxidant activity and polyphenols. For cocoa-containing foods, there has been no comprehensive survey of the content of these and other chemistries. A survey of cocoa and chocolate-containing products marketed in the United States was conducted to determine antioxidant activity and polyphenol and procyanidin contents. Commercially available samples consisted of the top market share products in each of the following six categories: natural cocoa, unsweetened baking chocolate, dark chocolate, semisweet baking chips, milk chocolate, and chocolate syrup. Composite samples were characterized using four different methods: oxygen radical absorbance capacity (ORAC), vitamin C equivalence antioxidant capacity (VCEAC), total polyphenols, and procyanidins. All composite lots were further characterized for percent nonfat cocoa solids (NFCS) and percent fat. Natural cocoas had the highest levels of antioxidant activities, total polyphenols, and procyanidins followed by baking chocolates, dark chocolates and baking chips, and finally milk chocolate and syrups. The results showed a strong linear correlation between NFCS and ORAC (R (2) = 0.9849), total polyphenols (R (2) = 0.9793), and procyanidins (R (2) = 0.946), respectively. On the basis of principal component analysis, 81.4% of the sample set was associated with NFCS, antioxidant activity, total polyphenols, and procyanidins. The results indicated that, regardless of the product category, NFCS were the primary factor contributing to the level of cocoa antioxidants in the products tested. Results further suggested that differences in cocoa bean blends and processing, with the possible exception of Dutching, are minor factors in determining the level of antioxidants in commercially available cocoa-containing products in the United States.
Asunto(s)
Antioxidantes/análisis , Biflavonoides/análisis , Cacao/química , Catequina/análisis , Flavonoides/análisis , Fenoles/análisis , Proantocianidinas/análisis , Antioxidantes/farmacología , Ácido Ascórbico/farmacología , Polifenoles , Especies Reactivas de Oxígeno/química , Estados UnidosRESUMEN
Ancient traditional Chinese medicine (TCM) has effectively relied on the theory of yin-yang balance in diagnoses and treatments of diseases and disorders for more than 2000 years. However, in eastern society, yin-yang is regarded as an incomprehensible ideology without definite physical meaning. Consequently, the yin-yang balance in medicine has not been studied by modern scientific means. In the western world, yin-yang balance is often misunderstood as a religious belief or a principle of lifestyle. Herein, we attempted to define the physical meaning of yin-yang in TCM by correlating it with biochemical processes. We propose that yin-yang balance is antioxidation-oxidation balance with yin representing antioxidation and yang as oxidation. Our proposal is partially supported by the fact that the yin-tonic traditional Chinese herbs have, on average, about six times more antioxidant activity and polyphenolic contents than the yang-tonic herbs. Our hypothesis opens an avenue to systematically study the yin-yang balance and its health implications with the use of modern biochemical tools.
Asunto(s)
Antioxidantes/metabolismo , Medicina Tradicional China , Plantas Medicinales/química , Oxidación-Reducción , Fenoles/metabolismo , Extractos Vegetales/química , Especies Reactivas de Oxígeno/metabolismoRESUMEN
The oxygen radical absorbance capacity (ORAC) assay has been widely accepted as a standard tool to measure the antioxidant activity in the nutraceutical, pharmaceutical, and food industries. However, the ORAC assay has been criticized for a lack of accessibility due to the unavailability of the COBAS FARA II analyzer, an instrument discontinued by the manufacturer. In addition, the manual sample preparation is time-consuming and labor-intensive. The objective of this study was to develop a high-throughput instrument platform that can fully automate the ORAC assay procedure. The new instrument platform consists of a robotic eight-channel liquid handling system and a microplate fluorescence reader. By using the high-throughput platform, the efficiency of the assay is improved with at least a 10-fold increase in sample throughput over the current procedure. The mean of intra- and interday CVs was Asunto(s)
Autoanálisis/métodos
, Especies Reactivas de Oxígeno/análisis
, Espectrometría de Fluorescencia/métodos
, Estabilidad de Medicamentos
, Colorantes Fluorescentes
, Radicales Libres/análisis
, Indicadores y Reactivos
, Luz
, Reproducibilidad de los Resultados
, Sensibilidad y Especificidad
RESUMEN
A total of 927 freeze-dried vegetable samples, including 111 white cabbages, 59 carrots, 51 snap beans, 57 cauliflower, 33 white onions, 48 purple onions, 130 broccoli, 169 tomatoes, 25 beets, 88 peas, 88 spinach, 18 red peppers, and 50 green peppers, were analyzed using the oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant capacity (FRAP) methods. The data show that the ORAC and FRAP values of vegetable are not only dependent on species, but also highly dependent on geographical origin and harvest time. The two antioxidant assay methods, ORAC and FRAP, also give different antioxidant activity trends. The discrepancy is extensively discussed based on the chemistry principles upon which these methods are built, and it is concluded that the ORAC method is chemically more relevant to chain-breaking antioxidants activity, while the FRAP has some drawbacks such as interference, reaction kinetics, and quantitation methods. On the basis of the ORAC results, green pepper, spinach, purple onion, broccoli, beet, and cauliflower are the leading sources of antioxidant activities against the peroxyl radicals.
Asunto(s)
Antioxidantes/análisis , Compuestos Férricos/química , Verduras/química , Autoanálisis , Liofilización , Oxidación-Reducción , Extractos Vegetales/análisis , Especificidad de la Especie , Espectrometría de Fluorescencia/métodos , Factores de TiempoRESUMEN
We recently reported the improved oxygen radical absorbance capacity (ORAC) assay using fluorescein (FL) as the fluorescent probe. The current ORAC(FL) assay is limited in hydrophilic antioxidant due to the aqueous environment of the assay. Lipophilic antioxidants mainly include the vitamin E family and carotenoids, which play a critical role in biological defense systems. In this paper, we expanded the current ORAC(FL) assay to lipophilic antioxidants. Randomly methylated beta-cyclodextrin (RMCD) was introduced as the water solubility enhancer for lipophilic antioxidants. Seven percent RMCD (w/v) in a 50% acetone-H(2)O mixture was found to sufficiently solubilize vitamin E compounds and other lipophilic phenolic antioxidants in 75 mM phosphate buffer (pH 7.4). This newly developed ORAC assay (abbbreviated ORAC(FL-LIPO)) was validated through linearity, precision, accuracy, and ruggedness. The validation results demonstrate that the ORAC(FL-LIPO) assay is reliable and robust. For the first time, by using 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid as a standard (1.0), the ORAC values of alpha-tocopherol, (+)-gamma-tocopherol, (+)-delta-tocopherol, alpha-tocopherol acetate, tocotrienols, 2,6-di-tert-butyl-4-methylphenol, and gamma-oryzanol were determined to be 0.5 +/- 0.02, 0.74 +/- 0.03, 1.36 +/- 0.14, 0.00, 0.91 +/- 0.04, 0.16 +/- 0.01, and 3.00 +/- 0.26, respectively. The structural information of oxidized alpha-tocopherol obtained by liquid chromatography/mass spectrometry reveals that the mechanism for the reaction between the vitamin E and the peroxyl radical follows the hydrogen atom transfer mechanism, which is in agreement with the notion that vitamin E is the chain-breaking antioxidant.