Cysteine Esters Protect Cultured Rodent Lung Slices from Sulphur Mustard

1 In previous studies an in vitro rat lung slice system was used to investigate the metabolic and structural changes after exposure to known lung toxicants. 2 In this study, the same system was used to identify the ability of cysteine esters to protect against sulphur mustard toxicity. 3 The cyclopentyl (CCPE), cyclohexyl (CCHE), isopropyl (CIPE), methyl (CME) esters of cysteine, cystine dimethyl ester (CDME), cysteine (CySH) and N-acetyl cysteine (NAc) were all non-toxic to cultured rat lung slices at 5 mM (equivalent cysteine concentration) after a pretreatment time of 30 min. 4 Pretreatment with the isopropyl, cyclohexyl, cyclopentyl and methyl esters of cysteine at concentrations higher than 1 mM protected against an IC50 of sulphur mustard, however, neither cysteine nor N-acetylcysteine protected. 5 We propose that the extent of protection is directly related to increased levels of intracellular cysteine provided by the esters of cysteine.