Evaluation of antioxidant potential of flavonoids: an in vitro study.

In recent years, there is an increasing interest in antioxidants. The main reason for this interest is the protection of cells, their organelles (especially membranes) and metabolic pathways against oxygen free radicals and their reactive derivatives (ROS). They participate in formation of chronic inflammation states and other diseases associated with oxidative stress, such as cancer, hypertension, atherosclerosis, cardiovascular and neurodegenerative diseases (1). Antioxidant compounds from dietary sources are receiving tremendous attention. Among them are flavonoids ñ the widely distributed group of secondary metabolites in the plant kingdom (2, 3). Flavonoids are inseparable elements of human diet. Their main sources are presented in Table 1. The most commonly-consumed flavonoids are quercetin, luteolin and apigenin. They appear mainly in the glycosidic forms with residues such as: D-glucose, L-rhamnose, galactose, arabinose (eg., quercetin-3glucoside, quercetin-3-rhamnoside, quercetin-3galactoside, quercetin-3-rutinoside (rutin)) (4). Flavonoids exhibit different biological activities influencing on numerous metabolic pathways. Due to their radical scavenging, antioxidant, anti-inflammatory, anti-allergic, anticancer, antiatherosclerotic, antiaggregational and detoxification activities they might be useful for prevention and treatment of many human diseases. Because of the wide spectrum of biological activities and the prevelance of flavonoids in daily life we decided to determine in present study an antioxidant activity of these compounds in in vitro model. Antioxidant activities of numerous flavonoids in plant extracts or natural formulations had intensively been studied (6ñ8), but little is known about properties of pure flavonoids. In this EVALUATION OF ANTIOXIDANT POTENTIAL OF FLAVONOIDS: AN IN VITRO STUDY