ABSTRACT
This study aimed to investigate the absorption mechanism of three curcumin constituents in rat small intestines. Self-emulsification was used to solubilize the three curcumin constituents, and the rat in situ intestinal perfusion method was used to study factors on drug absorption, including drug mass concentration, absorption site, and the different types and concentrations of absorption inhibitors. Within the scope of experimental concentrations, three curcumin constituents were absorbed in rat small intestines through the active transport mechanism.
Subject(s)
Animals , Male , Female , Adjuvants, Pharmaceutic/pharmacology , Curcumin/analogs & derivatives , Curcumin/pharmacokinetics , Enzyme Inhibitors/pharmacokinetics , Intestinal Absorption , Intestine, Small/metabolism , Reference Values , Time Factors , Uncoupling Agents/pharmacology , Verapamil/pharmacology , Probenecid/pharmacology , Reproducibility of Results , Chromatography, High Pressure Liquid/methods , Rats, Sprague-Dawley , ATP-Binding Cassette Transporters/antagonists & inhibitors , 2,4-Dinitrophenol/pharmacokinetics , Curcumin/chemistry , Multidrug Resistance-Associated Proteins/analysis , Multidrug Resistance-Associated Proteins/antagonists & inhibitors , Emulsions , Perfusion Imaging/methods , Intestinal Absorption/drug effects , Intestine, Small/drug effectsABSTRACT
The recent upsurge of antimony (Sb) resistance is a major impediment to successful chemotherapy of visceral leishmaniasis (VL). Mechanisms involved in antimony resistance have demonstrated an upregulation of drug efflux pumps; however, the biological role drug efflux pumps in clinical isolates remains to be substantiated. Thus, in this study, the functionality of drug efflux pumps was measured in promastigotes and axenic amastigotes isolated from VL patients, who were either Sb-sensitive (AG83, 2001 and MC9) or resistant (NS2, 41 and GE1) using rhodamine123 as a substrate for multidrug resistant (MDR) pumps and calcein as a substrate for multidrug resistance-associated proteins (MRP) respectively; their specificity was confirmed using established blockers. Sb-resistant (Sb-R) isolates accumulated higher amounts of R123, as compared to Sb-sensitive (Sb-S) isolates. Verapamil, a MDR inhibitor failed to alter R123 accumulation, suggesting absence of classical MDR activity. In Sb-R isolates, both promastigotes and axenic amastigotes accumulated significantly lower amounts of calcein than Sb-S isolates and probenecid, an established pan MRP blocker, marginally increased calcein accumulation. Depletion of ATP dramatically increased calcein accumulation primarily in Sb-R isolates, indicating existence of a MRP-like pump, which was more active in Sb-R isolates. In conclusion, our data suggested that overfunctioning of a MRP-like pump contributed towards generation of Sb-R phenotype in L. donovani field isolates.