Multidrug Resistance Assay Protocol

Fexofenadine hydrochloride and emodin were purchased from Tokyo Chemical Industry (Tokyo, Japan). Dimethyl sulfoxide (DMSO), terfenadine, verapamil, Dulbecco’s modified Eagle’s medium (DMEM) with high glucose, MEM non-essential amino acid solution (NEAA) and glutamine were purchased from Sigma-Aldrich (St. Louis, MO, USA). HPLC grade acetonitrile and water were purchased from Fisher Scientific Korea (Seoul, Korea). emodin, emodin-8-O-β-d-glucoside, chrysophanol, chrysophanol-8-O-β-d-glucoside, physcion and physcion-8-O-β-d-glucoside isolated from R. acetosa were obtained from the pharmacognosy laboratory of the College of Pharmacy at Gyeongsang National University (Jinju, Korea) [27 (link)]. Fetal bovine serum (FBS), N-2-hydroxyethylpiperazine–N′-2-ethanesulfonic acid (HEPES) and Hanks’ balanced salt solution (HBSS) were purchased from Corning (Manassas, VA, USA). Penicillin–streptomycin, Opti-MEM and 0.25% (w/v) trypsin–EDTA were purchased from Gibco (Carlsbad, CA, USA). Phosphate buffered saline (PBS) was purchased from Welgene (Gyeongsan, Korea). An MDR assay kit (fluorometric) was purchased from Abcam (Cambridge, UK).