Search

Diets or plant extracts (food supplements) rich in phytochemical antioxidants are able to reduce the incidence of non-communicable diseases such as cardiovascular diseases, diabetes, stroke and different types of cancer. Antioxidant properties are key criteria for the evaluation of the health-beneficial potential of a food, as a consequence, accurately assessing the antioxidant properties becomes critical. The various in vitro assay methods are important tools available for evaluating the antioxidant potential of foods. They are simple and can provide highly reproducible results for comparison of the different foods. A brief summary of the in vitro assay methods and in vivo commonly agreed key biomarkers and evidences is presented in this review. However, high antioxidant properties in vitro does not always lead to increased antioxidant values ex vivo or in vivo . Many factors can affect this, among them stability to stand the physicochemical and enzymatic degradation in the gastrointestinal tract, and bioavailability to the various tissues or organs of these phytochemicals are perhaps most important.

Background There is an urgent need to explore and utilize naturally occurring products for combating harmful agricultural and public health pests. Secondary metabolites in the leaves of the Tree of Heaven, Ailanthus altissima L. have been reported to be herbicidal and insecticidal. The mode of action, however, of the active compounds in A. altissima are not understood. In this paper, we report the chemical characteristics of the herbicidal and insecticidal components in this tree, and will discuss the effect of light on the bioactivity of the active components. Results Extracts from the fresh leaves of A. altissima showed a strong plant germination/growth inhibitory effect in laboratory bioassays against alfalfa (Medicago sativa). The effect was dose-dependent. The growth inhibitory components were in the methylene chloride soluble fraction of the extract. The effect was greater in the light than in the dark. Other fractions had plant growth enhancing effect at lower concentrations. The extract was slightly insecticidal against yellow fever mosquito larvae (Aedes aegypti). Conclusions The extract or its semi-purified fractions of A. altissima were strong plant growth inhibitors, therefore good candidates as potential environmentally safe and effective agricultural pest management agents. The finding that light affects the activity will be useful in the application of such natural products.