Toxic effects of triacylglycerol polymer on macrophages in vitro

Edible vegetable oil usually produces high concentration triglyceride polymer (TGP) after highly oxidative deterioration, and the toxic effects of TGP in animals are still under debate, with no definitive evidence supporting the toxicity of TGP in animals. The aim of the present study was to evaluate the toxicity of TGP on murine immunocytes. Cultured macrophages were treated with different concentrations of TGP, and then the quantity of live cells, phagocytic activity and lactate dehydrogenase (LDH) release were determined. Additionally, apoptosis was observed by laser scanning confocal microscopy and flow cytometry. The intracellular reactive oxygen species (ROS) level was also determined by flow cytometry. The results showed that the viability and phagocytic activity of macrophages were significantly inhibited by TGP, and elevated LDH release was observed in TGP-treated macrophages. TGP also significantly increased the intracellular ROS level and thus resulted in apoptosis of macrophages. These results suggest that TGP has obvious toxicity against immune function. Practical applications: Triacylglycerols in edible vegetable oil may form polar oxidized TGP by oxidization during the processes of storage, cooking and refining, especially high-temperature frying. The present study has demonstrated that TGP may cause significant toxicity in macrophages and therefore it can be employed as a quality control index for consumer cooking oil.