Coumberone is a metabolic fluorogenic probe and isoform-selective substrate for all AKR1C isoforms. It can be reduced by all four members of the AKR1C family to its fluorescent alcohol coumberol. Coumberone is a valuable tool for researching AKR1C.

Coumberone, at a concentration of 30 μM over 24 hours in HCT116 cells, serves as an AKR1C3 substrate, achieving its peak rates at approximately 10 μM[1]. When applied at 5 μM for 24 hours in COS-1 cells, Coumberone facilitates the selective optical readout of AKR1C isoforms, specifically AKR1C2 or AKR1C3[2]. Similarly, in IMR32 cells under the same conditions, it allows for real-time imaging of AKR1C induction[2]. Moreover, Coumberone metabolism is notably enhanced over 80 hours in IMR-32 cells, displaying a tenfold higher catalytic efficiency for AKR1C3 over AKR1C2 in vitro[2]. Its efficacy is highlighted by the ability to enable real-time AKR1C induction imaging in IMR32 cells with immunofluorescence at a concentration of 5 μM across 24 hours[2].