Oxygen Radical Absorbance Capacity of Bulgarian fruits, vegetables, herbs and mushrooms. A review

In search of novel sources of antioxidants in the recent years, traditional plant foods have been extensively studied for their antioxidant activity. Investigation of natural products is a research field with great potential and is especially important in countries possessing great biodiversity, like Bulgaria. About 600 plant species from Bulgarian flora are recognized as medicinal and are traditionally used in ethnopharmacology and phytotherapy. Given the huge interest in antioxidants, the large number of methods developed to give a quantitative assessment of antioxidant action is not surprising. Dozens of methods for determination of antioxidant activity in food and biological samples have been developed. The results reported in following sections are part of a long-term study of the Laboratory of biologically active substances, Institute of Organic Chemistry with Centre of Phytochemistry - Bulgarian Academy of Sciences, on antioxidant activity of Bulgarian fruits, vegetables, herbs and mushrooms. Results are obtained by the Oxygen Radical Absorbance Capacity (ORAC) method in which the inhibition time and inhibition degree can be measured. The ORAC method is relevant for biological samples, since it assesses the radical scavenging activity of the sample against peroxyl radicals, which physiologically are the most important ones. Besides, oxidation process is performed in water media, at physiological pH and temperature. Current review compiles data for antioxidant activity of 90 raw materials, including unpublished results for ORAC value of 11 mushrooms, 4 vegetables and 2 herbs.