Dipotassium phosphate

Acrylamide, acetonitrile, α-cyano-4-hydroxycinnamic acid, bis-Acrylamide, benzamidine, Bradford solution, p-coumaric acid, caffeic acid, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate hydrate (CHAPS), 1,4-dithiothreitol (DTT), ferulic acid, fluorescein (FL), γ-aminobutyric acid (GABA), gallic acid, 4-hydroxybenzoic acid, iodoacetamide, phenylisothiocyanate, syringic acid, sodium dodecyl sulfate (SDS), Trolox, trifluoroAcetic acid, thiourea, urea, and vanillic acid were purchased from Sigma Aldrich (St. Louis, MO, USA). Acetic acid, dipotassium phosphate, ethanol, hydrochloric acid, hexane, sodium hydroxide, monopotassium phosphate, methanol, and water were obtained from Junsei Chemical (Tokyo, Japan), and 2,2′-azobis(2-amidinoprpane) dihydrochloride solution (ABAP) was purchased from Wako Chemicals (Richmond, VA, USA). Pharmalyte (pH 3.5–10) and IPG Dry Strips (pH4–10 NL, 24 cm) were purchased from Amersham Biosciences and from Genomine Inc. (Pohang-si, Korea), respectively. Porcine trypsin was obtained from Promega (Madison, WI, USA).

Trolox, quercetin, fluorescein (FL), dimethyl sulfoxide (DMSO), 2′,7′-dichlorofluorescin diacetate (DCFH-DA), vanillic acid, caffeic acid, syringic acid, p-coumaric acid, syringaldehyde, ferulic acid, and sinapic acid were purchased from Sigma-Aldrich, Inc. (St. Louis, MO, USA). Monopotassium phosphate, dipotassium phosphate, ethanol, methanol, hydrochloric acid, sodium hydroxide, hexane, acetic acid, acetonitrile, and water were obtained from Junsei Chemical Co., Ltd. (Tokyo, Japan), and 2,2′-azobis(2-amidinoprpane) dihydrochloride solution (ABAP) was purchased from Wako Chemicals Inc. (Richmond, VA, USA). HT-29, Caco-2, HeLa, and HepG2 cells were obtained from the American Type Culture Collection (ATCC) (Manassas, VA, USA). McCoy’s 5A, MEM, fetal bovine serum (FBS), phosphate-buffered saline (PBS), and Trypsin-EDTA were purchased from Welgene (Daegu, Korea). Dulbecco’s Modified Eagle Medium (DMEM) was purchased from HyClone Laboratories Inc., (South Logan, UT, USA). A MTT cell proliferation assay kit and a Cell Death Detection ELISA^plus kit were purchased from Roche Ltd., (Indianapolis, IN, USA). The p-AKT, p-53, PTEN, β-Actin, Bax, Bcl-XL, and Mcl-1 were obtained from Cell Signaling Technology (Beverly, MA, USA). ECL prime western blotting detection reagent was purchased from GE Healthcare Life Sciences (Marlborough, MA, USA).

l-Tyrosine, l-3,4-dihydroxyphenylalanine (l-DOPA), arbutin, mushroom tyrosinase enzyme (EC 1.14.18.1), and α-melanocyte-stimulating hormone (α-MSH) were obtained from Sigma Aldrich (St. Louis, MO, USA). Dulbecco’s modified Eagle’s medium (DMEM), fetal bovine serum (FBS), and penicillin-streptomycin were purchased from Gibco-BRL Life Technologies (Grand Island, NY, USA). Primary tyrosinase (TYR) antibodies, β-actin, and horseradish peroxidase-conjugated secondary antibodies were obtained from Santa Cruz Biotechnology Inc. (Santa Cruz, CA, USA). Dipotassium phosphate and monopotassium phosphate were obtained from Junsei Chemical Co. Ltd. (Tokyo, Japan) and Yakuri Pure Chemicals Co. Ltd. (Osaka, Japan), respectively. All other reagents and solvents were purchased from E. Merck, Fluka, and Sigma-Aldrich unless otherwise stated.