UVB Photoprotective Role of Mycosporines in Yeast: Photostability and Antioxidant Activity of Mycosporine-Glutaminol-Glucoside

MOLINÉ, M; ARBELOA, EM; FLORES, MR; LIBKIND, DIEGO; FARIAS, ME; BERTOLOTTI, SG; CHURIO, MS; VAN BROOCK, M

RADIATION RESEARCH

RADIATION RESEARCH SOC

Año: 2011 vol. 175 p. 44 - 50

0033-7587

Several yeast species are able to synthesize and accumulate UV-radiation-absorbing mycosporine metabolites that are of unclear physiological function. In this work we analyzed the relationship between mycosporine-glutaminol glucoside (MGG) production, cell survival after UVB irradiation, and formation of cyclobutane pyrimidine dimers (CPDs). We also assessed the photostability and singlet oxygen quenching activity of MGG. A set of nine isolates of the basidiomycetous yeast Cryptococcus steppossus cultured in both dark and light conditions was used for the studies. Survival of the UVB-irradiated isolates and MGG concentration had a linear relationship when the concentration was over 2.5 mg g 1. CPD accumulation and MGG accumulation were inversely related. MGG in aqueous solution was photostable with a photodecomposition quantum yield of 1.16 10 5. MGG quenching of singlet oxygen was also observed, and the rate constant for the process in D2O was 5.9 107 M 1 s 1. Our results support the idea that MGG plays an important role as a UVB photoprotective metabolite in yeasts by protecting against direct damage on DNA and probably against indirect damage by singlet oxygen quenching