Rosemary-stimulated reduction of DNA strand breaks and FPG-sensitive sites in mammalian cells treated with H2O2 or visible light-excited Methylene Blue.

In this study possible protective effects of rosemary against oxidative DNA damage induced by H2O2- and visible light-excited Methylene Blue in colon cancer cells CaCo-2 and hamster lung cells V79 were investigated. The level of DNA damage (DNA strand breaks) was measured using the classical and modified single cell gel electrophoresis, so-called comet assay. Our findings showed that an ethanol extract from rosemary reduced the genotoxic activity of both agents after a long-term (24 h; 0.3 microg/ml) or short-term (2 h; 30 microg/ml) pre-incubation of cells. We suggest that the extract of rosemary exhibits a protective effect against oxidative damage to DNA as a consequence of scavenging of both *OH radicals and singlet oxygen ((1)O2).