Indigo carmine (CAS No 860-22-0) is a synthetic dye often used in biomedical research particularly in studies related to its origin from indigoid compounds It acts primarily as a redox indicator and is known for its application in tracking renal function during medical procedures The mechanism of action involves interaction with biological pathways where it serves as a visual marker due to its color change from blue to yellow under varying conditions In vitro its activity is observed in the nanomolar to low micromolar range reflecting its pronounced visibility in cellular environments It is frequently applied in cell models and animal studies to assess drug absorption and distribution Moreover indigo carmine is employed as a screening tool in pharmacokinetic studies Experimental concentrations typically depend on the specific research design ensuring adaptability across various experimental setups