Zhimin Xu
School of Nutrition and Food Sciences, Louisiana State University
Phytochemicals are secondary plant metabolites widely present in the plant kingdom. Most of the phytochemicals are phenolic derivatives with monohydric or polyhydric phenols which are mainly responsible for their antioxidant function. Numerous clinical studies have confirmed that antioxidant phytochemicals can prevent some cholesterol-related and lipid oxidation induced chronic diseases. The antioxidant properties and health benefits of phytochemicals in different agricultural food plants have been intensively studied in recent years. This presentation will discuss the antioxidant phytochemicals in common fruits, vegetables, and grains and their potentials to reduce the risk of developing chronic diseases.
The presentation will also introduce a lipid/water emulsion model method to assess the antioxidant activity of phytochemicals or natural product extracts. The emulsion consists of the fatty acids and cholesterol which are commonly existing in the human serum and susceptible to be oxidized by free radicals reaction. It has been confirmed that the serum lipid oxidation could produce enormous lipid oxidation products to initiate the cellular inflammations of blood vessels and lead to the development of cardiovascular and other chronic diseases. In the emulsion model, the retained rate of the fatty acids and cholesterol during a certain period is correlated with the antioxidant activity of an added test sample against the lipid oxidation. The activity obtained in the emulsion model could closely represent the capability of preventing the serum lipid oxidation and inhibiting the production of harmful lipid oxidation products. Compared with a single solvent or aqueous reaction media used in the traditional antioxidant activity assays, the emulsion model method was relatively more specific and reliable to reflect the antioxidant performance or health promoting potential of a test sample in inhibiting the lipid oxidation under an environment similar to the human serum. In general, the information delivered in this presentation will be very useful for the industries and scientists in natural products research and development area to better understand and evaluate various antioxidant phytochemicals in agricultural products.
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