ascorbic-acid and flavan-3-ol

White tea (WT) is rich in flavan-3-ols as green tea (GT) and might provide health protective effects due to the strong antioxidant properties of flavan-3-ols. Since intervention studies with WT are lacking, we evaluated the effects of WT consumption on antioxidant status, antioxidant capacity and biomarkers of oxidative stress compared to water and GT. After an overnight fast, 70 healthy non-smokers were randomized to consume 600 mL of WT, GT or water (control). Plasma (epi-)catechin and epi(gallo)catechingallate, antioxidant capacity (Folin assay, trolox equivalent antioxidant capacity test), 8-iso-prostaglandin F(2α), ascorbic acid and uric acid were determined before and several times within 8 h after consumption. DNA strand breaks were measured in vivo and ex vivo (H(2)O(2) stimulation) in leukocytes. Plasma flavan-3-ols significantly increased after WT and GT ingestion. Trolox equivalent antioxidant capacity was lower after 5 h in controls versus WT (p = 0.031) and GT (p = 0.005). Folin-Ciocalteu reducing capacity, ascorbic and uric acid as well as markers of oxidative stress (8-iso-prostaglandin-F(2α), DNA strand breaks) were not affected by the beverages. A short-term increase of catechins does not change plasma antioxidant capacity in healthy subjects. Conclusions with respect to health protective effects of WT and GT on the basis of these biomarkers can, thus, not be drawn.

Topics: Adult; Antioxidants; Ascorbic Acid; Biomarkers; Catechin; Female; Flavonoids; Humans; Hydrogen Peroxide; Leukocytes; Male; Oxidative Stress; Plant Extracts; Plasma; Smoking; Tea; Young Adult

The nutritional quality and antioxidant capacity of China domestic kiwifruit and imported kiwifruit with different prices and the relationships of retail price among cultivars, nutritional qualities and flesh color were investigated. Results showed that cultivar was the main factor influencing nutritional quality, though the product region could also affect the cultivar characteristics to some extent. Additionally, nutritional quality and antioxidant capacity of kiwifruit had no relationship to the product region. What's more, there was no correlation among the nutrient compositions, antioxidant capacity and retail price of kiwifruit. At the same time, the flesh color was associated with greater commercial value but was not higher nutritional quality or antioxidant capacity. Thus indicates to consumers that imported kiwifruit were not all superior to local versions, and the priciest kiwifruit did not equal to the most nutritious kiwifruit, also the color kiwifruit. There still need more research to help consumers to choose kiwifruit.

Topics: Actinidia; Amino Acids; Anthocyanins; Antioxidants; Ascorbic Acid; China; Color; Dietary Proteins; Flavonoids; Fruit; Metals, Heavy; Nutritive Value; Phenols; Phenylurea Compounds; Pyridines; Trace Elements

The aim of this study was to determine the effect of different dying methods, such as convective drying (CD: 50, 60, 70 °C), vacuum-microwave drying (VMD: 120, 480, 480-120 W), a combination of convective pre-drying and vacuum-microwave finish drying [(CPD (60 °C)-VMFD (480-120 W)], and freeze-drying (FD) on key quality parameters of dried jujube fruits (cv. "GAL", "MSI", and "PSI"). The parameters studied included bioactive compounds (flavan-3-ols and flavonols, identified by LC-PDA-MS, and vitamin C), antioxidant capacity (ABTS and FRAP), and sensory attributes (e.g. hardness, jujube-ID, and sweetness). The best quality of the dried product (high contents of bioactive compounds and high intensity of key sensory attributes) was found in fruits treated by FD and VMD 480-120 W. The best cultivars were "PSI" and "GAL" from the point of view of bioactive content and sensory quality, respectively.

Topics: Antioxidants; Ascorbic Acid; Desiccation; Flavonoids; Flavonols; Food, Preserved; Freeze Drying; Fruit; Genetic Variation; Microwaves; Ziziphus

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.

Topics: Antioxidants; Ascorbic Acid; Biflavonoids; Cacao; Catechin; Flavonoids; Phenols; Polyphenols; Proanthocyanidins; Reactive Oxygen Species; United States

Cocoa flavanols and procyanidins have numerous biological activities. It is known that (-)-epicatechin, (+)-catechin, epicatechin-(4beta-8)-epicatechin (dimer B2), and epicatechin-(4beta-6)-epicatechin (dimer B5) are unstable at physiologic pH, degrading almost completely within several hours, whereas they are relatively stable at pH 5.0. The present study investigated the effects of ascorbic and citric acid on the stability of monomers and dimers in simulated intestinal juice (pH 8.5) and in sodium phosphate buffer (pH 7.4). The addition of ascorbic acid to the incubation mixture significantly increased the stability of the monomers and dimers, whereas the addition of citric acid provided no protective effects. LC-MS showed that with the degradation of dimer B2 and dimer B5, doubly linked A-type dimers were formed. The present results, although not directly transferable to in vivo conditions, suggest that ascorbic acid may stabilize cocoa flavanols and procyanidins in the intestine where the pH is neutral, or alkaline, before absorption.

Topics: Ascorbic Acid; Biflavonoids; Body Fluids; Cacao; Catechin; Citric Acid; Dimerization; Drug Stability; Flavonoids; Hydrogen-Ion Concentration; Intestines; Proanthocyanidins