Novel pyxinol amide derivatives bearing an aliphatic heterocycle as P-glycoprotein modulators for overcoming multidrug resistance

Design, synthesis, and biological evaluation of C-12 modified ocotillol-type derivatives as novel P-glycoprotein modulators for overcoming multidrug resistance

Ocotillol-type ginsenoside derivatives exhibit significant potential as modulators of P-glycoprotein (Pgp). To date, structural investigations of Ocotillol-type saponins have predominantly focused on modifications at the C-3 position of the A-ring, with limited exploration of the C-12 position on the C-ring. In this study, we designed and synthesized a series of C-12 modified ocotillol-type derivatives and assessed their efficacy in reversing multidrug resistance (MDR) in KBV cells. Most of the newly synthesized derivatives exhibited minimal cytotoxicity and potent MDR reversal capabilities. Notably, compound 9e emerged as the most effective agent in reversing tumor MDR in vitro, showing more than twice the potency of verapamil. Furthermore, 9e displayed high selectivity for Pgp, being 40- and 20-fold more effective than verapamil in inhibiting Rh123 efflux and enhancing doxorubicin sensitivity, respectively. Molecular docking analysis revealed that 9e possesses a unique T-shaped configuration that occupies the access channel of Pgp, obstructing the peristaltic extrusion mechanism of TM12 and TM9, thereby inhibiting the efflux function of Pgp. Overall, 9e represents a promising lead compound for the development of novel Pgp modulators to overcome MDR in cancer therapy.

Design, synthesis, and biological evaluation of β-carboline derivatives as ABCB1 inhibitors for reversing multidrug resistance

The scarcity of ATP-binding cassette subfamily B member 1 (ABCB1, also known as P-glycoprotein, P-gp) inhibitors suitable for clinical application in improving multidrug resistance (MDR) promotes the development of drugs aimed at reversing MDR. In this work, we reported a comprehensive study for the first time about the reversal activity of β-carboline derivatives on ABCB1-mediated MDR. Among 48 synthesized derivatives, compound K27 significantly increased the sensitivity of ABCB1-mediated MDR SW620/AD300 cells to paclitaxel (PTX) (IC50 = 15.33 ± 5.4 nM, RF = 171.2) and hardly showed toxicity even at a high concentration of 20 μM when used alone. The in vitro studies indicated that compound K27 distinctly enhanced the arresting effect of PTX on the SW620/AD300 cell cycle, thereby inhibiting their proliferation. Mechanistically, compound K27 was confirmed to directly bind to ABCB1 to inhibit efflux function, reducing cellular efflux and ensuring stable intracellular concentration of PTX without affecting ABCB1's normal expression. Importantly, the combination of compound K27 and PTX exhibited potent tumor suppression in vivo without generating toxicity. These results demonstrated that β-carboline compounds represented by compound K27 may be potent ABCB1 inhibitors with considerable potential in effectively reversing ABCB1-mediated MDR, showing promising prospects.