CHEMBL3888229

Discontinuous Radiometric Assay: Compounds may be evaluated as selective reversible inhibitors of AKR1C3 by screening them against homogeneous recombinant AKR1C1-AKR1C4 expressed in E. coli. In each case, a discontinuous radiometric assay may be used to monitor the inhibition of progesterone reduction (20-ketosteroid reduction) catalyzed by AKR1C1, the inhibition of Δ4-AD reduction (17-ketosteroid reduction) catalyzed by AKR1C3, and the inhibition of 5α-DHT reduction (3-ketosteroid reduction) catalyzed by AKR1C2 and AKR1C4 (by measuring the formation of 20α-hydroxyprogesterone, testosterone or 3α-androstanediol by radiochromatography). Secondary screens of the compounds of interest include: (a) a full-screen against all nine human recombinant AKR enzymes to ensure there are no-intended off-target effects (in this context AKR1B10 (retinal reductase; SEQ ID NO:5) has been shown to be potently inhibited by N-phenylanthranilates) (Endo et al., 2010, Biol. Pharm. Bull. 33:886-90); (b) a screen against COX-1 and COX-2 to reaffirm that compounds do not act as NSAIDs; and (c) an expanded screen against other nuclear receptors (especially other steroid hormone receptors).