Catalyzes the NADPH-dependent reduction of carbonyl compounds to their corresponding alcohols (PubMed:18493841). Has low NADPH-dependent oxidoreductase activity. Acts on several orthoquinones, acts as well on non-quinone compounds, such as isatin or on the anticancer drug oracin (PubMed:15537833, PubMed:18493841, PubMed:19841672). Best substrates for CBR3 is 1,2- naphthoquinone, hence could play a role in protection against cytotoxicity of exogenous quinones (PubMed:19841672). Exerts activity toward ortho-quinones but not paraquinones. No endogenous substrate for CBR3 except isatin has been identified (PubMed:19841672).
