A derivative and metabolite of coumarin with diverse biological activities; inhibits growth of human ACHN renal, A549 lung, HCT15 colon, and LNCaP prostate carcinoma as well as Dakiki myeloma and HL-60 lymphoma cells at 250-300 μg/ml; increases ROS production and halts the cell cycle in KB human oral carcinoma cells; has antidepressant-like activity in a rat model of depression induced by chronic unpredictable mild stress at 15 and 30 mg/kg; used as a ratiometric pH indicator with ex/em = 330 and 370/460 nm at low and high pH, respectively