Se‐allylselenocysteine suppresses inflammation via inhibiting iNOS expression

Abstract

Se‐allylselenocysteine (ASC), an analogue of garlic compound, has been shown to inhibit mammary carcinogenesis in vivo and cell growth in vitro. However, the function of ASC on anti‐inflammatory effect remains largely unknown. Therefore, we investigated whether ASC has anti‐inflammatory effects on LPS‐induced inflammation.We first tested the effect of ASC on cell viability to exclude the possibility that the decreased nitrite production in ASC‐treated cells was due to growth inhibition. According to the results, ASC didn't show cytotoxic effects on RAW 264.7 macrophages. The inflammatory process is associated with the activation of inflammatory macrophages, which release inflammatory mediators, such as NO. To evaluate the inhibitory effects of ASC on LPS‐stimulated nitric oxide (NO) production in RAW 264.7 cells, the cells were treated with LPS (100 ng/mL) only or with different concentrations of ASC for 24 h. At the end of incubation time, plasma level of nitrite in the culture media of LPS‐activated macrophages was determined using Griess method. The results showed that LPS‐induced nitrite production was reduced significantly in 50μM of ASC‐treated RAW 264.7 macrophages.We also detected the effects of ASC on the LPS‐induced expressions of inducible nitric oxide synthase (iNOS) protein in RAW 264.7 cells. Likewise, iNOS expression was inhibited markedly by ASC at 50μM in a similar manner. These results indicate that the reduced expressions of iNOS by ASC were responsible for the inhibition of LPS‐induced NO production. In summary, the current study speculates that iNOS played a crucial role in anti‐inflammatory effects of ASC on LPS‐induced inflammation.