Pentosidine in advanced glycation end-products (AGEs) during UVA irradiation generates active oxygen species and impairs human dermal fibroblasts

Our previous study reported that advanced glycation end-products (AGE)-modi fied BSA produced active oxygen species, O-.(2)-. H2O2, and (OH)-O-. under UVA irradiation and enhanced the cytotoxicity of UVA light. We examined whe ther pentosidine in AGE-modified BSA was involved in one of the mechanisms generating the active oxygen species. In biological investigations, fibrobl asts exposed to UVA (20 J/cm(2)) in the presence of pentosidine-rich compou nds (PRCs), which were prepared with L-arginine, L-lysine and glucose, show ed a time-dependent leakage of the cytosolic enzyme LDH. In addition, relea se of LDH was suppressed by addition of DMSO and deferoxamine under UVA irr adiation. From these results, it was determined that PRCs exposed to UVA da maged the plasma membrane of human dermal fibroblasts due to the conversion of (OH)-O-. from H2O2 via a Fenton-like reaction. These features of PRCs e xposed to UVA were consistent with those of AGE-modified BSA. In an ESR stu dy, PRCs under UVA irradiation yielded DMPO-OH (DMPO-OH adduct) using DMPO as a spin-trapping reagent. O-.(2) generation from UVA-irradiated PRCs was also indicated by the combination of NBT reduction and SOD. When PRCs were exposed to UVA light controlled with a long-pass filter, WG-360, it was fou nd that their production of O-.(2)- was prohibited less than 50% in the NBT reduction assay. The O-.(2)- production profile of PRCs depending on the w avelength of UVA light was similar to that of AGE-modified BSA. Furthermore , it was found that the H2O2 level was increased by PRCs exposed to UVA. Th ese results indicated that pentosidine is an important factor of AGE-modifi ed BSA in active oxygen generation under UVA irradiation. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.