Abstract
Several herbal beverages claim medicinal benefits due to their antioxidant properties. However, operational factors such as the extracted herbal component, preparation method or concentration levels, might influence their biological activity. To assess this effect, the antioxidant activity of beverages prepared with Camellia sinensis, Aspalathus linearis or Cochlospermum angolensis, used solely or mixed with different fruit, plant or algae extracts, was studied using different formulations (bags, leaves, roots, granulates, powders, liquids) and different preparation methods (infusion, solubilisation or promptly used). The DF50 (dilution factor responsible for 50% of antioxidant activity) values were calculated to compare their antioxidant activity. A linear discriminant analysis was used to categorize the assayed samples according to their antioxidant activity and bioactive molecules profiles. The results indicated that antioxidant activity and antioxidant compounds are significantly affected by formulation and preparation method, but overall the labelled antioxidant benefits were validated. Green tea showed the highest activity, but with different behaviour within each used formulation. The high DF50 values calculated for some products might be used to adjust the dietary dose or formulation, preventing also putative pro-oxidant effects. Hence, the obtained results might be useful to define the formulation of these highly consumed herbal beverages, enhancing their health effects.
Highlights
Under stress, living organisms produce more reactive oxygen species (ROS, e.g., superoxide anion radicals, hydroxyl radicals and hydrogen peroxide) than enzymatic and non-enzymatic antioxidants, causing an imbalance that may lead to cell damage and health problems [1]
In order to obtain a comprehensive knowledge about the effect of diluting the herbal beverage concentration, the complex chemical composition of natural matrices should be considered
The results showed that either preparation method or formulation influence the antioxidant properties of “teas”
Summary
Under stress, living organisms produce more reactive oxygen species (ROS, e.g., superoxide anion radicals, hydroxyl radicals and hydrogen peroxide) than enzymatic (e.g., superoxide dismutase, glutathione peroxidase, and catalase) and non-enzymatic (e.g., ascorbic acid, -tocopherol, glutathione, carotenoids, and flavonoids) antioxidants, causing an imbalance that may lead to cell damage and health problems [1]. When consumed within a balanced diet, these herbal beverages may have the capacity to improve the antioxidant status, preventing oxidative damage in humans [13], reducing cardiovascular disease and some forms of cancer, exerting a neuroprotective effect, as well as preventing other disorders related to oxidative stress [13,15], including the control of cellular redox dysfunction linked to type 2 diabetes [16]. These functions have been attributed to their high content of polyphenols (catechins or flavan-3-ols, theaflavins, thearubigins and proanthocyanidins) [17]. Besides finding the most effective formulations, it was intended to verify if the doses recommended in labels are adequate to guarantee the aimed antioxidant effects
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