Cytotoxicity of the polymerization agent, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone on human monocytes

This is the first study to detect 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMP) from an intravenous injection bag solution by GC-MS. In previous studies, several other photoinitiators were reported to be very cytotoxic. Therefore, we theorized that photoinitiators such as MTMP might also have adverse cellular effects. The purpose of this study was to quantitate the amounts of contaminants from plastic containers such as those used for peripheral parenteral nutrition and to determine the cytotoxicity of such extracts on human monocytes. The sample extraction procedure for GC-MS analysis involved a liquid-phase extraction. The solvent was evaporated under a stream of nitrogen at 50°C. The residue was dissolved in n-hexane and injected into a GC-MS. Normal human peripheral blood mononuclear cells (PBMC), isolated from the buffy coat by centrifugation, were suspended in RPMI 1640 medium supplemented with 10% (v/v) heat-inactivated fetal calf serum. In the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cells (1×10(4)) were treated with MTMP for 24 h or 48 h at 37°C. From the GC-MS analysis, 5.62 ± 1.03 μg/mL of MTMP was found in the BFLUID(®) Injection 500 mL solution. In the MTT assay, MTMP decreased cell viability in a dose-dependent manner for both the 24 h and 48 h incubation periods. Our findings suggest that photoinitiators could promote adverse effects in patients. Future studies will clarify the possible health risks of photoinitiator accumulation in human cells.