Modulation by pinoresinol and its derivatives of cell multidrug resistance mediated by the P-glycoprotein efflux pump.

LAIOLO J.; VERA D.M.A.; GONZÁLEZ M.L.; JORAY M.B.; PALACIOS S. M.; RUMJANEK V; CARPINELLA M.C

Simposio; IX International Symposium on natural products chemistry and applicaions; 2016

Introduction P-Glycoprotein (P-gp) is an ATP- dependent efflux pump responsible for the efflux of hundreds of structurally unrelated agents, including anticancer drugs. This trans-membrane pump is associated to multidrug resistance (MDR), being one of the major barriers to successful chemotherapy treatment. According to previous studies it has been determined that the lignan pinoresinol, isolated from Melia azedarach, showed reversal properties of the MDR mediated by P-gp. By performing molecular modelling studies it was determined the binding properties of pinoresinol derivatives in order to identify compounds with improved activity with respect to the lead compound. According to the obtained results the most favored in decreasing order was 1-acetoxypinoresinol (1) > phylligenin > 1-hydroxypinoresinol > pinoresinol 4-glucoside > pinoresinol > pinoresinol diglucoside. As observed compound 1 deserve further analysis. Materials and methods Compound 1 was tested in K562 human myelogenous leukemia cell line and its MDR counterpart Lucena 1. Its effect on doxorubicin (DOX) cytotoxicity was evaluated by the multidrug resistance reversal assay (MTT). Intracellular DOX accumulation was then determined by flow cytometry. The cytotoxicity of 1 on peripheral blood mononuclear cells (PBMC) was further evaluated by the MTT assay. Data were analyzed using Student´s t test or one or two-ways analysis of variance (ANOVA), regarding p-values ≤ 0.05 as statistically significant. All experiments were performed at least three times. Results and conclusion Compound 1 was 64 times more active than pinoresinol according to the minimum effective concentrations (MECs) obtained by the reversal (0.11 and 7 μM, respectively) and the accumulation assays (0.87 and 56 μM, respectively), demonstrating an outstanding improved activity. Also 1 presented the same level of activity than that observed with the reference compound verapamil. On the other hand, 1 showed no potentiation in DOX activity at 14 μM in K562 cells. The IC50 of 1 was 102.6 μM on PBMC (almost 1000 times higher than the MECs). In conclusion, the results obtained positioned this compound as potential candidate to overcome P-gp-mediated MDR in lights of a better outcome of leukemia chemotherapy.