Albumin Affects the Inhibition of UDP-Glucuronosyltransferase (UGT) 2B7 by Cervical Carcinoma Treatment Drug Andrographolide

Andrographolide is an important herbal component isolated from Andrographis paniculata undergoing the research and development (R&D) as the anti-tumor drug. Comparison of the inhibition of andrographolide towards UGT2B7 activity was performed between the incubation mixture without and with BSA: 0.5% BSA addition can significantly strengthen the inhibition potential of andrographolide towards UGT2B7. Furthermore, the inhibition kinetics were determined. The intersection point was located in the horizontal axis in the Lineweaver-Burk plot, indicating the competitive inhibition of andrographolide towards UGT2B7. Through the fitting the slopes from Lineweaver-Burk plot versus the concentrations of andrographolide, the fitting equation was y = 202.24 x + 100. Using this equation, the inhibition kinetic parameter (Ki) was calculated to be 0.5 uM. Using this parameter and reported plasma concentration of andrographolide (2.28 mu g/mL, (6.5 mu M), the [I]/Ki value was calculated to be 13 ([I]/Ki < 0.1, not possible; 0.1 < [I]/Ki < 1, possible; [I]/Ki > 1, highly possible), indicating very highly possible drug-drug interaction between andrographolide and clinical drugs mainly undergoing UGT2B7-catalyzed reaction. In conclusion, the influence of BSA towards the inhibition of andrographolide towards the activity of UGT2B7 was demonstrated, which benefits the optimization of the in vitro incubation system for the evaluation of andrographolide's inhibition towards UGT2B7.