A study of inactivation reactions of N-acetylcysteine with mucochloric acid, a mutagenic product of the chlorination of humic substances in water.
The Salmonella typhimurium (TA100) mutagenic compound, mucochloric acid [3,4-dichloro-5-hydroxy-2(5H)-furanone (MCA)], was inactivated by in vitro N-acetylcysteine (NAC). The reaction of MCA with NAC at pH7 was second order and gave products 4, 5, and 6a that resulted from the displacement of chlorine from C-3 or C-4 of MCA. The sodium borohydride treatment of product 4 gave the same product (7) as was obtained by treating 3,4-dichloro-2(5H)-furanone with NAC. The treatment of MCA with (R)-(+)-cysteine gave the bicyclic product 9a, in which the two chlorine atoms of MCA were still present. This product was slightly more mutagenic than MCA, whereas product 5 was less mutagenic than MCA and product 4 was nonmutagenic in the Salmonella typhimurium (TA100) assay.
LaLonde
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Department of Chemistry, College of Environmental Science and Forestry, State University of New York, Syracuse 13210-2786.
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D000111:Acetylcysteine / Q000737:chemistry*; D001894:Borohydrides / Q000737:chemistry; D005663:Furans / Q000737:chemistry / Q000633:toxicity*; D009152:Mutagenicity Tests; D009153:Mutagens / Q000737:chemistry / Q000633:toxicity*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics
D001894:Borohydrides; D005663:Furans; D009153:Mutagens; C014117:mucochloric acid; C025364:sodium borohydride; D000111:Acetylcysteine