Purpose: Oral drug development had been hindered by the bioavailability issue
despite vast market popularity. Lipid excipients have shown to enhance
bioavailability of several reformulated hydrophobic oral drugs, yet the underlying
mechanisms of action by lipids are still unclear. One proposed mechanism is that
lipid could facilitate drug uptake by altering the activities of apical membrane
intestinal efflux transporters. Thus, this study aimed to investigate the effects of
specific monoglycerides on the efflux activity and protein expression of multidrug
resistance-associated protein 2 (MRP2) in vitro.
Methods: A preliminary study was first conducted to determine the effect of
Peceol®, a mono- and di-glyceride mixture, on MPR2 efflux activity. Then, the 24-
hour non-cytotoxic ranges of specific monoglycerides (1-monopalmitin, 1-
monostearin and 1-monoolein) were determined using MTS and LDH assays in
Caco-2 cells. Then, the effects of chosen monoglycerides on the functional
activity of MRP2 were assessed via rhodamine 123 (Rh123) accumulation and
estradiol 17 β-D-glucuronide(E₂17βG) bidirectional transport studies. The dose
responses of Rh123 accumulation with each monoglyceride treatment were also
determined. Lastly, Western blotting was used to probe the monoglycerides
effect on MRP2 protein expression.
Results: In the preliminary study, significant increase in Rh123 accumulation
and decrease in E₂17βG efflux ratio were observed in Peceol® treated cells. The
non-cytotoxic concentration ranges for 1-monopalmitin, 1-monostearin and 1-
monoolein were within 1 mM, 1 mM and 500 μM, respectively. Cells treated with
1 mM 1-monoplamitin, 1 mM 1-monostearin, 500 μM 1-monoolein and 50 μM
MK571 (a MRP2 inhibitor) resulted in significant increases in Rh123
accumulation and decreases in E₂17βG efflux ratio compared to the control
(medium treated only). The three monoglycerides did not show Rh123
accumulation in a dose-responsive manner. MRP2 protein expressions in 1-
monopalmitin and 1-monoolein treated cells were decreased by 19% and 35%,
respectively; however, there was no change of MRP2 protein expression in 1-
monostearin treated cells.
Conclusions: These findings suggested that 1-monoolein, 1-monostearin and 1-
monopalmitin could attenuate the activity of MRP2 and possibly other efflux
transporters in Caco-2 cells. The reduction of efflux activity of MRP2 by 1-
monoolein treatment could be partially explained by the non-specific down
regulation of MRP2 protein expression.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/4132 |
| Date | 11 1900 |
| Creators | Jia, Xi Jessica |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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