Studies done on camphoroquione, an initiator of light induced polymerization have shown that it is cytotoxic and induces lipid peroxidation in association with enhancers such as dimethylaminoethyl methacrylate (DMAEMA), via generation of free radicals. Objective: The purpose of our study was to observe the effects of toxic as well as sub-toxic concentrations of camphoroquinone on lipid metabolism of HCP (hamster cheek pouch) and THP-1 (monocyte) cells. Methods: The mitochondrial dehydrogenase activity (MTS) assay was used to determine the sub-toxic concentration of camphoroquinone at 24hrs for both cell lines. To observe the effects on lipid metabolism cells were exposed to sub-toxic concentration of camphoroquinone and labeled with ¹⁴C acetate at the same time for 24hr. Lipids were extracted using the Bligh & Dyer method and were separated using thin layer chromatography. Percent total lipids were compared in treated vs. control cultures by Student's t test (p<0.05). Lipid peroxidation was assessed by measuring nmols/ml of thiobarbituric acid reactive substances (TBARS) at toxic concentrations of camphoroquinone. Results: Toxic concentrations of camphoroquinone such as 1-2.5mM or greater induced lipid peroxidation in cells at 40 minutes. Sub-toxic concentration of camphoroquinone (0.5mM) showed changes in lipid synthesis. Phospholipid synthesis was decreased along with an increased synthesis of neutral lipids such as cholesterol and triglycerides in THP-1 cells. Sphingomyelin was decreased in HCP cells, along with an increase in triglycerides. Conclusion:Toxic concentrations of camphoroquinone induced lipid peroxidation while a sub-toxic concentration induced significant changes in lipid metabolism. Thus, lipid peroxidation induced effects on cell membranes may be related to the toxic effects of this polymerization initiator. The effects of sub-toxic concentrations on lipid metabolism may lead to alteration in membrane composition as well as membrane permeability. Supported by R01-DE-11980 from NIDCR. MP5618GS@students.mcg.edu

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