A CASE-SAR study of mammalian hepatic azoreduction

A group of 36 aryl azo dyes were examined for their ability to be reduced by rat liver microsomal azoreductase. This group of azo dyes featured a variety of substituents, including sulfonic acid, phenol, nitro, amide, and methyl functionalities on phenyl, alpha-naphthyl, and beta-naphthyl rings. Reduction rates for each dye were obtained using a spectrophotometric method and anaerobic incubation conditions. These rates ranged from 0 to 7.35 nmol dye reduced/min.mg protein. The reduction rates and dye structures provided the data for a CASE-SAR (computer automated structure evaluation-structure-activity relationship) fragment analysis, and three major structure fragments associated with the ability of this group of azo dyes to be reduced were identified. The three CASE fragments correctly label 92% of the azo dye structures as active or inactive and may be useful in future predictions of the ability of azo dyes to undergo reduction by rat liver azoreductase.