Correlation of calculated molecular orbital energies of some phenothiazine compounds with MDR reversal properties.

Molecular orbital energies of energetically minimized series of extended aromatic and aminoalkyl side chain substituted phenothiazine compounds have been considered with respect to charge transfer (CT) binding properties to P-glycoprotein (P-gp) amino acids of the first P-gp loop. A dependency of decreasing energies of lowest unoccupied orbitals (E(lumo)) with reduced CT binding properties to an increasing P-gp mediated multidrug resistance (MDR) has been found for the extended aromatic compounds.