Protection of riboflavin and UVB sensitized degradation of DNA and RNA bases by natural antioxidants

Riboflavin (RF) is a potent photosensitizer producing extensive degradation of purine and pyrimidine derivatives of nucleic acids under UVA, UVB and sunlight. In this study we have demonstrated that reactive O-2 species generated by photosensitized RF under UVB were responsible for the degradation of DNA and RNA bases. While O-1(2) accounted for the degradation of adenine, guanine, thymine and uracil, O-2(-) also contributed to partial degradation of adenine. Cytosine remained unaffected by the synergistic action of RF and UVB. Ascorbic acid, glutathione, glycolic acid and quercetin showed remarkable protection (88-100%) against photodegradation of bases. Sorbitol was effective in preventing photodegradation of guanine. These naturally occurring antioxidants are potential candidates for prevention against oxidative stress caused by photosensitization. (C) 2011 Elsevier Inc. All rights reserved.