Citation:

Vilas-Boasa, V, Silva R, Nunes C, Reis S, Ferreira L, Vieira C, Carvalho F, de Bastos ML, Remiao F.  2013.  Mechanisms of P-gp inhibition and effects on membrane fluidity of a new rifampicin derivative, 1,8-dibenzoyl-rifampicin, JUL 18. TOXICOLOGY LETTERS. 220:259-266., Number 3

Abstract:

Purpose: To assess P-glycoprotein (P-gp)-modulation ability and the mechanisms of P-gp inhibition mediated by a new synthetic rifampicin derivative, 1,8-dibenzoyl-rifampicin (DiBenzRif), in an in vitro model of the blood-brain barrier (BBB), RBE4 cells, and in membrane mimetic models (liposomes). Methods: P-gp expression (western blot) and activity {[}rhodamine 123 accumulation studies] were assessed until 72 h of exposure to DiBenzRif. The effects on intracellular ATP levels and on P-gp ATPase activity were studied using luciferin-luciferase bioluminescence assay. Membrane fluidity changes were tracked by steady-state anisotropy measurements. Non-P-gp-related rhodamine 123 accumulation was evaluated using liposomes prepared with the main lipids present in RBE4 cell membranes. Results: A significant increase in intracellular rhodamine 123 content was observed in DiBenzRif-treated cells at all tested time-points. This effect was associated with a significant reduction in ATP intracellular levels, the inhibition of P-gp ATPase activity and a significant increase in membrane fluidity. DiBenzRif also favoured rhodamine 123 accumulation in a liposomal model of RBE4 cells, suggesting that it may be useful in increasing intracellular levels of substances that passively diffuse into the cells. Conclusion: DiBenzRif-induced inhibitory effect on P-gp increases xenobiotic accumulation in BBB cells, which may contribute to the development of therapeutic adjuvants to enhance brain penetration of drugs. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

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