Glutathione-dependent dechlorination of chloramphenicol by cytosol of rat liver.

The 100,000 g supernatant fraction (cytosol) of rat liver converts chloramphenicol (CAP, RNHCOCHCl2) into two products. Most of the enzyme activity is lost during dialysis of the enzyme preparation overnight, but is restored by addition of glutathione (GSH). Other thiols are not as effective as GSH in restoring the enzyme activity. The formation of the metabolites is not inhibited when incubations are performed under anaerobic conditions. The major metabolite was identified as CAP aldehyde (RNHCOCHO) whereas the minor metabolite was identified as an alkali-unstable derivative of CAP oxamic acid (RNHCOCOOH). Plausible pathways are discussed for the formation of these metabolites.