ABSTRACT
Objective: To study the effects of coumarins in Angelicae Dahuricae Radix (imperatorin, isoimperatorin, bergapten, and oxypeucedanin) on the activities of adenosine triphosphate (ATPase) in P-glycoprotein (P-gp) in vitro and to investigate the P-gp mediated meschanism in transport of drug. Methods: The ATPase activity assay was used to identify whether the coumarins in Angelicae Dahuricae Radix were P-gp substrates or not. Results: The average fluorescent values (ΔRLUTC) of imperation and oxypeucedanin at each concentration were greater than average basic fluorescence value (ΔRLUbasal). The average fluorescent values (ΔRLUTC) in medium and low concentration of isoimperatorin and bergapten groups were lower than average basic fluorescence value (ΔRLUbasal). Conclusion: Imperation and oxypeucedanun are non-concentration dependent P-gp ATP inhibitors. Isoimperatorin and bergamot lactones could inhibit the ATPase activity at low concentration and have the inhibitory effect on P-gp. At high concentration, the activity of ATPase can be induced so as to induce P-gp.