Strong antioxidant activity of ellagic acid in mammalian cells invitro revealed by the comet assay. Festa F, Aglitti T, Duranti G, Ricordy R, Perticone P, Cozzi R. Dipartimento di Biologia, Universita degli Studi Roma TRE, Italy.Oxidative stress due to oxygen and various radical species is associatedwith the induction of DNA single- and double-strand breaks and is consideredto be a first step in several human degenerative diseases, cancer andageing. Naturally occurring antioxidants are being extensively analysed fortheir ability to protect DNA against such injury. We studied three naturallyoccuring compounds,Ascorbic Acid, Melatonin and Ellagic acid, for theirability to modulate DNA damage produced by two strong radical oxygeninducers (H2O2 and Bleomycin) in cultured CHO cells. The alkaline Cometassay was used to measure DNA damage and a cytofluorimetric analysis wasperformed to reveal the intracellular oxidative species. The data showed amarked reduction of H2O2- and Bleomycin-induced DNA damage exerted byEllagic Acid. On the contrary Ascorbic acid and Melatonin appeared to inducea slight increase in DNA damage per se. In combined treatments, they causeda slight reduction of H2O2-induced damage, but they did not efficientlymodulate the Bleomycin-induced one. The Dichlorofluorescein diacetate(DCFH-DA)cytofluorimetric test confirmed the strong scavenging actionexerted by Ellagic Acid.