Methylthiazol 2 yl 2 5 diphenyl tetrazolium bromide mtt

Methanol, acetonitrile, and formic acid for high-performance liquid chromatography (HPLC) were of HPLC grade and purchased from Merck (Darmstadt, Germany). Solvents for sample extraction including ethanol, dichloromethane, and n-butanol were of analytical grade. Deionized water was purified using a Milli-Q ultrapure water system (Millipore, Bedford, Massachusetts, MA, USA) and employed in all the experiments. Phenolic standard compounds of gallic acid, rutin, Trolox, and vitamin C were purchased from Chengdu Must Bio-Technology Co., Ltd. (Chengdu, China). Methylthiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT), Folin–Ciocalteu reagent, 2,2ʹ-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), 1,3,5-tri(2-pyridyl)-2,4,6-triazine (TPTZ), 2ʹ,7ʹ-dichlorofluorescin diacetate (DCFH-DA), and FeSO₄·7H₂O were purchased from Sigma–Aldrich (Shanghai, China). The NMR spectra were obtained using Bruker AV-400, and/or DRX-500 spectrometers. ESIMS spectra were recorded on An Agilent 1290 UPLC/6540 Q-TOF spectrometer.

Arbutin (purity > 98%), dimethyl sulfoxide (DMSO), V_C (purity > 99%), 20,70-dichlorofluorescin diacetate (DCFH-DA), and methylthiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) were purchased from Sigma-Aldrich (St. Louis, MO, USA). B16 and HepG2 cells were obtained from the Kunming Cell Bank. Phosphate-buffered saline (PBS), fetal bovine serum (FBS), Dulbecco’s modified Eagle’s medium (DMEM), and penicillin/streptomycin were obtained from Servicebio (Wuhan, China). 1,3,5-tri(2-pyridyl)-2,4,6-triazine (TPTZ), 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2-diphenyl-1-pi-crylhydrazyl radical (DPPH), Folin–Ciocalteu reagent, Trolox, and levodopa were purchased from Sigma-Aldrich (Shanghai, China). Nitric oxide (NO), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH), Annexin V−Fluorescein Isothiocyanate (FITC)/Propidium Iodide (PI) cell apoptosis detection kits, and a BCA protein assay kit were purchased from the Beyotime company (Beijing, China). ELISA kits for interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) were purchased from MultiSciences (Lianke) Biotech Co. (Hangzhou, China). Tyrosinase and an intracellular tyrosine kinase activity detection kit were obtained from Sigma-Aldrich.