ABSTRACT
I. General Background on Phytochemicals as Antioxidants ...................................................127 II. Possible Antioxidant Mechanisms of Flavonoids ................................................................128 III. Evidence that Flavonoids Act as Antioxidants.....................................................................129 IV. Flavonoids and Lipoprotein Oxidation.................................................................................132 V. Evidence for Specific Antioxidant Mechanisms of Flavonoids...........................................133 VI. Prooxidant Effects of Flavonoids .........................................................................................138 VII. Summary ...............................................................................................................................138 References ......................................................................................................................................138
The oxidant reactions of free radicals, molecules with unpaired electrons, are thought to contribute to many health problems (reviewed in Reference 1). Antioxidants are agents which restrict the deleterious effects of oxidant reactions. These effects can be direct (i.e., eliminating certain free radicals) or indirect (i.e., preventing radical formation). The body produces certain endogenous antioxidants (i.e., certain enzymes) and antioxidants can be consumed in the diet. Some dietary antioxidants, such as vitamin E, are essential nutrients (the body cannot function normally without them). The diet also contains other components potentially capable of antioxidant actions. These belong to the class of food components known as phytochemicals. These compounds, such as the flavonoids, are not absolutely required parts of the diet, but may confer health benefits such as antioxidant actions.
