EFFECTS OF PYRROLOQUINOLINE QUINONE (PQQ) AND PQQ-OXAZOLE ON DNA-SYNTHESIS OF CULTURED HUMAN FIBROBLASTS

The effects of pyrroloquinoline quinone (PQQ) and PQQ-oxazole (PQQ-gly cine adduct) on DNA synthesis were examined using cultured human fibro blasts. Confluent fibroblasts were cultured in serum-free Dulbecco's m odified Eagle's media, and various concentrations of PQQ and PQQ-oxazo le were added to the media. After incubation for 24 h, [H-3]thymidine was added to the media as an indicator for DNA synthesis of the cells. The thymidine incorporation into the cells was significantly enhanced even in the presence of very low concentrations of PQQ (0.003-0.03 mu M); it remained significantly enhanced, up to 30 muM PQQ. However, the incorporation remarkably decreased at 750-1500 muM of PQQ. In contras t to the results for PQQ, DNA synthesis was not stimulated by addition of 0.003-3 muM PQQ-oxazole, but it was slightly enhanced at concentra tions 15-750 muM. In morphological examination of the cultured human f ibroblasts, cell density was increased by addition of 0.003-30 muM PQQ when compared with that of the control, supporting the above biochemi cal data. However, there were no distinct differences in morphological effect between PQQ and PQQ-oxazole.