Inhibition of oxidative DNA damage by plant antioxidants

Reactive oxygen species (ROS), from both endogenous and exogenous sources, may be involved in aging and different human diseases such as atherosclerosis, cancer, diabetes, neurodegenerative diseases and acquired immunodeficiency syndrome (AIDS) (Olinski et a!., 2002). Natural antioxidants contained in medicinal and aromatic plants, fruits and vegetables may be useful in preventing the deleterious consequences of oxidative damage caused by ROS and therefore they are considered as possible chemopreventive agents. They can possess a variety of biological activities e.g. anti-mutagenic, anti-carcinogenic, anti-proliferative, scavenging of free radicals or activated mutagens/carcinogens, they can modulate DNA repair and other enzyme activities or even regulate gene expression (Brigelius-Flohe and Traber, 1999; Craig, 1999; Heo et a l., 2001; Mi t i c et a!., 2001; Lazarova and Slamenova, 2004; Niko li c et a!., 2004). In our previous work, we have shown that terpenoids from sage (Salvia officinalis L.) and basil (Ocimum basilicum L.) possess antimutagenic potential in prokaryotic and lower eukaryotic test systems (Vukovi6Gac i c et a!., 1993; Simi c et a!., 1998,2000; Mi ti c et a!', 2001). For estimation of their mechanism of action, it is very important to determine the potential to prevent oxidative DNA damage.