Cytotoxic and genotoxic potential of the type I photoinitiators BAPO and TPO on human oral keratinocytes and V79 fibroblasts.
OBJECTIVES
Phenylbis(acyl) phosphine oxide (BAPO) and diphenyl(acyl) phosphine oxide (TPO) are alternative photoinitiators to camphorquinone (CQ) in dental resinous materials. Aim of this study was to investigate their cytotoxic/genotoxic potential in human oral keratinocytes (OKF6/Tert2) and Chinese hamster lung fibroblasts (V79) in comparison to CQ.


METHODS
Cells were exposed to different concentrations of BAPO and TPO (1-50μM). Cytotoxicity was evaluated using H33342 and MTT assay, cell proliferation by BrdU proliferation assay and microscopy. Effects on cellular redox homeostasis were assessed by detecting intracellular levels of reactive oxygen/nitrogen species (ROS/RNS) using the DCFH2 assay and by quantification of mRNA expression of oxidatively regulated, cyto-protective enzymes. Genotoxic potential was determined by use of micronucleus (MN) assay.


RESULTS
BAPO and TPO induced a concentration-dependent decrease of cell number. BAPO and TPO showed 50- to 250-fold higher cytotoxicity than CQ. In contrast to CQ, both photoinitiators revealed no increase of intracellular ROS/RNS. However, BAPO (10μM) at least significantly induced mRNA-expression of redox-regulated proteins after 24h similar to 2.5mM CQ. Additionally, BAPO significantly raised the number of micronuclei, but only in V79 cells (10μM: 12±1, 2.5mM CQ: 15±1, medium control: 6±3). However, it also significantly decreased proliferation of these cells (10μM BAPO: 19.8%±7.3% compared to controls).


SIGNIFICANCE
BAPO and TPO revealed concentration-dependent cytotoxic effects in human oral keratinocytes and V79 cells. However, in contrast to CQ, no generation of intracellular ROS/RNS was found. Only BAPO induced genotoxicity in V79 cells.
['Popal|Marina|M|', 'Volk|Joachim|J|', 'Leyhausen|Gabriele|G|', 'Geurtsen|Werner|W|']
D000818:Animals D002164:Camphor D049109:Cell Proliferation D002478:Cells, Cultured D003412:Cricetulus D003497:Cyclic N-Oxides D005347:Fibroblasts D006801:Humans D066298:In Vitro Techniques D015603:Keratinocytes D008168:Lung D008422:Materials Testing D015162:Micronucleus Tests D009152:Mutagenicity Tests D018384:Oxidative Stress D058567:Photoinitiators, Dental D017382:Reactive Oxygen Species
Cytotoxicity Genotoxicity Phenylbis(acyl) phosphine oxides Diphenyl(acyl) phosphine oxides Camphorquinone