Benzo[a]phenoxazines: A new group of potent P-glycoprotein inhibitors

Olga Wesolowska, Joseph Molnar, Gunnar Westman, Kristin Samuelsson, Masami Kawase, Imre Ocsovszki, Noboru Motohashi, Krystyna Michalak

Research output: Contribution to journalArticle

19 Citations (Scopus)


The ability of fifteen novel phenoxazine derivatives (four phenoxazines and eleven benzo[a]phenoxazines) to modulate multidrug resistance (MDR) in a P-gp-overexpressing mouse T lymphoma cell line (L5178 MDR) was studied. A flow cytometric functional test, based on the differential accumulation of rhodamine 123 by sensitive and multidrug-resistant cells, was employed. Seven benzo[a]phenoxazines were observed to increase the amount of rhodamine 123 accumulated by resistant cells, i.e. to be new effective MDR modulators. The results allowed us to draw preliminary conclusions about the structural features of benzo[a]phenoxazines which are important for MDR modulation.

Original languageEnglish
Pages (from-to)109-114
Number of pages6
JournalIn Vivo
Issue number1
Publication statusPublished - Jan 1 2006



  • Flow cytometry
  • Multidrug resistance
  • P-glycoprotein
  • Phenoxazine derivatives

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology

Cite this

Wesolowska, O., Molnar, J., Westman, G., Samuelsson, K., Kawase, M., Ocsovszki, I., Motohashi, N., & Michalak, K. (2006). Benzo[a]phenoxazines: A new group of potent P-glycoprotein inhibitors. In Vivo, 20(1), 109-114.