Pervilleines B and C, new tropane alkaloid aromatic esters that reverse the multidrug-resistance in the hollow fiber assay

P-Glycoprotein (Pgp)-mediated drug efflux can yield a multidrug-resistance phenotype that is associated with poor response to cancer chemotherapy. Pervilleines B and C (PB and PC), two new tropane alkaloid aromatic esters obtained from a chloroform extract of the roots of Erythroxylum pervillei as the result of bioactivity-guided fractionation, were found to restore the vinblastine (VLB) sensitivity of cultured multidrug-resistant KB-V1 cells, with 50% inhibitory concentration values of 0.17 μM in each case. To explore the potential relevance of this response, KB-V1 cells were placed in hollow fibers and implanted into NCr nu/nu mice. Cell growth was not significantly inhibited when VLB or PB or PC were administered as single agents, but when used in combination with vinblastine inhibition of up to 77.7% was observed. Equimolar doses of verapamil were less effective. These data suggest that PB and PC are effective inhibitors of Pgp and should be further evaluated for clinical utility.