Abstract

Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as a gasoline antiknock additive. However, the toxic effect of MMT is currently not well understood. In this study, we investigated the toxic effect of MMT on rat thymocytes using a flow cytometer and fluorescent probes. MMT at 100–300 µM significantly increased the population of cells exhibiting propidium fluorescence, i.e., the population of dead cells. The intensity of BES-So-AM fluorescence significantly increased when using 100 µM MMT. In addition, the intensity of oxonol fluorescence in rat thymocytes increased with the treatment with MMT in a concentration-dependent manner (10–100 µM). The toxic effect of MMT was inhibited by quercetin, antioxidant flavonoid. Moreover, co-treatment with 30–100 µM MMT and 100 µM H₂O₂ increased the cell lethality further. These results indicate that MMT increases cell vulnerability to oxidative stress on rat thymocytes. This study provides insight into the toxic effect of MMT on the immune system.