Flavonoids are phytochemicals exhibiting a wide range of biological activities, among which are antioxidant activity, the ability to modulate activity of several enzymes or cell receptors and possibility to interfere with essential biochemical pathways. Flavonoids (bioflavonoids) comprise a large group of secondary metabolites are present in all plants. These are the pigments responsible for the coloration of flowers and leaves. Flavonoids are important for normal growth, development and defense plants. In addition, a very important part of human nutrition as found in fruits, vegetables, nuts, wine and tea, and is often due high pharmacological efficiency called "color-health". Average daily intake of flavonoids in foods is 1 to 2 grams. Today nutritionists all more use of flavonoids in the treatment of many diseases, because of the proven ability of flavonoids that inhibit specific enzymes, hormones and neurotransmitters. Studies have shown that flavonoids are good "scavengers" of free radicals, and thus play an important role in the pharmaceutical and food industries as pharmaceuticals and antioxidants. It has been shown that flavonoids have antibacterial, sedative, antiallergic, antimutagenic, antiviral and other effects. Some flavonoids possess prooxidant properties, which sometimes depends on the type of flavonoids, but also on the dose used amount. The sensitivity of a cell to free radical attack apparently depends on the relationship among antioxidant enzymes rather than on absolute activities of individual antioxidant enzymes.