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As soon as the role of Reactive Oxygen Species (ROS) in so-called civilization diseases, which include non-infectious chronic diseases such as cancer, diabetes or high blood pressure has been discovered, and the possibility of employing antioxidants as a remedy for these diseases have been proposed, scientists developed a broad spectrum of methods to determine antioxidant activity of pure chemicals and plant extracts, as well as dietary supplements. Most of these methods are based on simple redox reactions between antioxidant and ROS (for example ABTS, DPPH, or FRAP tests). However, chemical methods of assessing antioxidant activity are rarely biologically relevant. They do not mirror the real effect of antioxidants in living organisms, because they are used in non-physiological conditions of temperature and pH; neither they take metabolism nor intracellular transport under consideration. The perfect model for assessment of antioxidant activity in living organisms would be human or animal model, but such determinations are very complicated and often ambiguous. The current best alternative to chemical and human tests are assays employing cell culture models being less expensive than human tests, yet still reflecting biological systems more convincingly than chemical assays. Cellular antioxidant assays are performed under physiological pH and temperature, but most importantly, they take metabolism and intracellular transport under consideration. In this review, we present cellular tests used to determine antioxidant activity that are based on luminescence and fluorescence methods.

In the rational human diet, the important role of fruits and vegetables, which are a source of bioactive phytochemicals, is emphasized. Among fruits particular attention, due to a number of documented health-promoting properties, is focused on cranberry. This fruit is characterized by the high content of antioxidant phenolic compounds, which may support the natural antioxidant defense system of the body in the prevention of damage caused by oxidative stress induced by reactive oxygen species (ROS). Therefore, cranberry is suggested for the prevention of civilization diseases such as atherosclerosis, hypertension and cancer, whose etiology is associated directly with oxidative stress. The health-promoting potential of cranberry is also associated with its antibacterial activity resulting from the presence of proanthocyanidins (PAC) type A with documented anti-adherence properties. The best-established medical applications of cranberry fruits are prevention and treatment of bacterial infections of the urinary tract (UTI), infections of gastric mucosa, and infections of the oral cavity. Due to the widespread use of cranberry and pharmaceutical preparations containing PACs in treating UTI, it is very important to evaluate the absorption, bioavailability and metabolism of these compounds in the human body.