Cholestenone- 13 C 2 is the 13 C labeled Cholestenone. Cholestenone (4-Cholesten-3-one), the intermediate oxidation product of cholesterol , is metabolized primarily in the liver. Cholestenone is highly mobile in membranes and influences cholesterol flip-flop and efflux. Cholestenone may cause long-term functional defects in cells.