Definition:

NADPH-dependent oxidoreductase which catalyzes the reduction of a variety of compounds bearing carbonyl groups including steroids, retinoids and xenobiotics. Catalyzes the reduction/inactivation of 5alpha-dihydrotestosterone to 3alpha-androstanediol, with a possible role in the modulation of androgen receptor function. Involved in the reduction of all-trans-retinal to all-trans-retinol. Converts cortisone to 20beta-dihydrocortisone in vitro, although the physiological relevance of this activity is questionable. Reduces exogenous compounds such as quinones (1,2-naphtoquinone, 9,10-phenantrenequinone and benzoquinone) and other xenobiotics (alpha-diketones) in vitro, suggesting a role in the biotransformation of xenobiotics with carbonyl group. A dehydrogenase activity has not been detected so far. May play a role as tumor suppressor.