Development Of A Method For Detection And Identification Of Selenoamino Acids In Selenium-enriched Products And Their Anticancer Activity

Selenium is an essential micronutrient for the human body and the active center of selenium-containing enzymes,which plays a very important role in biological metabolism.Many studies have proved that insufficient or high intake of selenium directly or indirectly affects human health.Many endemic diseases,such as Keshan disease and Kashin-Beck disease,are directly related to selenium deficiency.The human body absorbs different forms of selenium slightly differently.Inorganic selenium such as sodium selenate and sodium selenite are cheap but highly toxic,so their usage is strictly limited;while organic selenium such as selenoproteins and selenoamino acids have the characteristics of low toxicity and high bioavailability,is a source of selenium permitted for human and animal use.Therefore,the ability to accurately analyze organic selenium such as selenoamino acids in selenium-enriched products is crucial for rational selenium supplementation and food safety.Many studies have shown that some organoselenium compounds,such as selenoamino acids and selenoproteins,have certain chemopreventive properties,such as inhibiting cell proliferation,inducing cell cycle arrest and apoptosis,and regulating redox status.Although both in vivo and in vitro anticancer effects of organic selenium have been reported,the data sometimes have conflicting results,so further research is needed.There is extensive heterogeneity between cells,and one manifestation of this heterogeneity is certain differences in the type and content of metabolites in the same cell.Currently,many single-cell mass spectrometry techniques have been developed to identify intracellular metabolites and discover new biological mechanisms through single-cell metabolomic analysis.Based on the above background,we mainly carried out two parts of work:1.Based on the national food safety standard "Determination of Amino Acids in Food",the method of hydrolyzing proteins with hydrochloric acid is improved,and the problem of instability of selenoamino acids in a strongly acidic environment is improved by adding a reducing agent TCEP.The best extraction conditions are obtained by optimizing the type,concentration and volume of the reducing agent;the best detection conditions are obtained by optimizing the composition of the mobile phase,the integration time of ICP-MS and other factors.An analytical method for selenoamino acids extracted by hydrochloric acid hydrolysis and detected by HPLC-ICP-MS was established,and it was applied to the detection of selenium-enriched Cardamine hirsute L.2.Using single-cell mass spectrometry to explore the differential metabolites of selenocystine before and after administration in vitro,revealing the heterogeneity between cells,and finding characteristic differential metabolites such as GSH.We continued to explore the possible anti-cancer mechanism of selenocystine,and found that A549 lung cancer cells treated with selenocystine showed increased intracellular reactive oxygen species content,mitochondrial structure and dysfunction.This demonstrates that selenocysteine may induce apoptosis in A549 cancer cells through a mitochondria-dependent oxidative stress mechanism.