Identification of Binding Sites in the Nucleotide-Binding Domain of P-Glycoprotein for a Potent and Nontoxic Modulator, the Amine-Containing Monomeric Flavonoid .

We have previously discovered an amine-containing flavonoid monomer as a potent P-glycoprotein (P-gp) inhibitor (EC = 83 nM). Here, a series of photoactive analogues were synthesized and used together with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify the -binding sites on P-gp. Point mutations around the photo-crosslinked sites were made for verification.

Discovery of a Flavonoid FM04 as a Potent Inhibitor to Reverse P-Glycoprotein-Mediated Drug Resistance in Xenografts and Improve Oral Bioavailability of Paclitaxel.

Biotransformation of flavonoid dimer FD18 resulted in an active metabolite FM04. It was more druggable because of its improved physicochemical properties. FM04 (EC50 = 83 nM) was 1.

Characterization of a Potent, Selective, and Safe Inhibitor, Ac15(Az8), in Reversing Multidrug Resistance Mediated by Breast Cancer Resistance Protein (BCRP/ABCG2).

Overexpression of breast cancer resistance transporter (BCRP/ABCG2) in cancers has been explained for the failure of chemotherapy in clinic. Inhibition of the transport activity of BCRP during chemotherapy should reverse multidrug resistance. In this study, a triazole-bridged flavonoid dimer was identified as a potent, nontoxic, and selective BCRP inhibitor.

A New Class of Safe, Potent, and Specific P-gp Modulator: Flavonoid Dimer FD18 Reverses P-gp-Mediated Multidrug Resistance in Human Breast Xenograft in Vivo.

Flavonoid dimer FD18 is a new class of dimeric P-gp modulator that can reverse cancer drug resistance. FD18 is a potent (EC50 = 148 nM for paclitaxel), safe (selective index = 574), and selective P-glycoprotein (P-gp) modulator. FD18 can modulate multidrug resistance toward paclitaxel, vinblastine, vincristine, doxorubicin, daunorubicin, and mitoxantrone in human breast cancer LCC6MDR in vitro.

Amine linked flavonoid dimers as modulators for P-glycoprotein-based multidrug resistance: structure-activity relationship and mechanism of modulation.

Here we report a great improvement in reversal potency of cancer drug resistance when flavonoid dimers possess a functionally substituted aminopolyethylene glycol linker. The most potent compound, 18, contains a N-benzyl group at the linker. It has many advantages including (1) high potencies in reversing P-glycoprotein (P-gp) mediated resistance in LCC6MDR cells to various anticancer drugs with EC(50) in the nanomolar range, (2) low toxicity and high therapeutic index, and (3) preferential inhibition of P-gp over multidrug resistance protein 1 and breast cancer resistance protein.

Design and syntheses of permethyl ningalin B analogues: potent multidrug resistance (MDR) reversal agents of cancer cells.

A series of novel N-arylalkyl-3,4-diaryl-substituted pyrrole-2,5-diones were synthesized. They exhibited promising P-gp modulating activity in a P-gp overexpressing breast cancer cell line (LCC6MDR). Compound 6 (with three methoxy groups at D-ring) displayed the highest P-gp modulating activity.

Flavonoid dimers as bivalent modulators for p-glycoprotein-based multidrug resistance: structure-activity relationships.

We recently described the modulatory activities of apigenin homodimers linked by ethylene glycol units in multidrug- resistant breast cancer and leukemic cells overexpressing ABCB1 (P-glycoprotein, P-gp). To further improve the potency of these dimers, a small library of flavonoid homodimers and heterodimers were synthesized, and their in vitro activity in reversing cellular resistance to paclitaxel, along with structure-activity relationships (SAR), were evaluated using a P-gp-expressing human breast cancer cell line. Among these synthesized homodimers, many showed more potent reversing activity than that of the parent compound and verapamil.