文摘
Free radicals are involved in different regulatory and pathological processes. The formation of superoxide in living cells or whole organisms is of major interest. ESR spin trapping allows identification of the radicals if proper spin traps are available. Our study investigates the toxicity of novel derivatives of the spin trap EMPO to cultured human lung carcinoma cells (A549), breast carcinoma cells (SKBR3), colon carcinoma cells (SW480) as well as to human fibroblasts (F2000). A dose-dependent decrease of the cell number was observed for all spin traps. At 100 mM BuMPO, t-BuMPO and s-BuMPO caused pronounced cell loss (>90 % ) and increased LDH-release, while DEPMPO, EMPO, PrMPO and i-PrMPO caused only moderate cell loss (<60 % ) without any effect on the LDH-release after 24 h. At 10 mM and 50 mM the latter agents even decreased LDH-release. 10 mM and 50 mM of i-PrMPO as well as 10 mM PrMPO increased intracellular GSH content acting like antioxidants, whereas 50 mM s-BuMPO and PrMPO decreased GSH content by 67 % and 38 % , respectively. Staining for apoptotic nuclei did not reveal any differences between controls and treated cultures indicating necrotic cell death possibly due to membrane toxicity. The following toxicity ranking was obtained: t-BuMPO > BuMPO > s-BuMPO > PrMPO > i-PrMPO DEPMPO EMPO. The least toxic compounds were DEPMPO (LD50 = 143 mM for SW480, 117 mM for A549 or 277 mM for F2000) and i-PrMPO (LD50 = 114 mM for SKBR3), the most toxic one was t-BuMPO (LD50 = 5–6 mM for all cell types). In conclusion, up to 50 mM i-PrMPO (t1/2 = 18.8 min) and up to 10 mM s-BuMPO (t1/2 = 26.3 min) can be recommended for further investigation of superoxide in biological systems.
