ABSTRACT
Reactive oxygen species (ROS) are produced as a part of normal metabolic processes. Under normal physiological conditions, the redox state is tightly controlled by antioxidants. However, increased production of ROS can overwhelm the antioxidant defenses, leading to an imbalance of oxidants and antioxidants in favor of oxidants and imposing oxidative stress on the physiological system (Sies 1997). The oxidative damages caused by ROS on lipids, proteins and nucleic acids may trigger various chronic diseases. Several studies have shown that ROS are involved in the etiology of many diseases, such as aging, cancer, atherosclerosis, coronary heart diseases, diabetes, asthma and rhinitis (Dhalla et al. 2000, Eberhardt et al. 2000, Bowler and Crapo 2002, Hussain et al. 2003, Maritim et al. 2003, Neumann et al. 2003). Epidemiological studies have established an inverse correlation between intake of fruits and vegetables and mortality from age-related diseases like cancer, atherosclerosis, diabetes and ageing, which could be partly attributed to their antioxidants (Gey 1990, Stephens et al. 1996, Eberhardt et al. 2000, La Vecchia et al. 2001). On the other hand, synthetic antioxidants have been widely used in food industry to prolong the shelf life. However, there is widespread agreement that some synthetic antioxidants such as butylhydroxyanisole and butylhydroxytoluene need to be replaced with natural antioxidants because they were found to be toxic and carcinogenic in animal models (Ito et al. 1986, Safer and Al-Nughamish 1999).Therefore, it is very important to fi nd out new sources of safe and inexpensive antioxidants of natural origin.
