Elucidation of Selenium Metabolism in mammalian cells by speciation

将人肝癌HepG2细胞暴露于亚硒酸钠后，采用高效液相色谱（HPLC）和电感耦合等离子体质谱（ICP-MS）联用，在细胞质部分检测到一种未知的硒代谢物。在外源谷胱甘肽（GSH）存在的情况下，HepG2匀浆和亚硒酸钠的混合物中也检测到未知的硒代谢物。通过电喷雾电离质谱（ESI- ms）和ESI四极杆飞行时间质谱（ESI- q - tof - ms）鉴定未知硒代谢物为硒氰酸酯。与亚硒酸盐或氰化物相比，硒氰酸盐对HepG2细胞的毒性较小，表明其形成是为了降低亚硒酸盐的毒性。另一方面，硒氰酸酯可以在大鼠体内被硒蛋白和硒代谢物同化。因此，亚硒酸盐被代谢为硒氰酸盐，以暂时改善其毒性，硒氰酸盐作为内在硒池。

When human hepatoma HepG2 cells were exposed to sodium selenite, an unknown selenium metabolite was detected in the cytosolic fraction by HPLC coupled with an inductively coupled plasma mass spectrometer (ICP-MS). The unknown selenium metabolite was also detected in the mixture of HepG2 homogenate and sodium selenite in the presence of exogenous glutathione (GSH). The unknown selenium metabolite was identified as selenocyanate by electrospray ionization mass spectrometry (ESI-MS) and ESI quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS). Selenocyanate was less toxic to HepG2 cells than selenite or cyanide, suggesting that it was formed to reduce the toxicity of selenite. On the other hand, selenocyanate could be assimilated to selenoproteins and selenometabolites in rats. Consequently, selenite was metabolized to selenocyanate to temporarily ameliorate its toxicity, and selenocyanate acted as an intrinsic selenium pool.