Tricetin

Acetonitrile and methanol of HPLC grade were purchased from Sigma-Aldrich (St. Louis, MO, USA). Quercetin 3-methyl ether, eriodictyol, ampelopsin (dihydromyricetin), taxifolin (dihydroquercetin), aromadendrin (dihydrokaempferol), tamarixetin, quercetin 3,3'-dimethyl ether, isokaempferide, chrysoeriol, homoeriodictyol, and isoferulic acid were purchased from BioBioPha Co., Ltd (Kunming, China), and oroxylin A was purchased from Shanghai Yuanye Bio-Technology Co., Ltd (Shanghai, China). Laricitrin, syringetin, and tricetin were from Extrasynthese (Lyon, France), and tricin was from ChromaDex (Irvine, CA, USA). Quercetin, isorhamnetin, kaempferol, luteolin, baicalein, eriocitrin, SAM, and formic acid for HPLC were obtained from Aladdin (Shanghai, China). Myricetin, apigenin, and 7,8-dihydroxyflavone hydrate were purchased from TCI (Shanghai, China). Caffeic acid, naringenin, hesperetin, neoeriocitrin, and ferulic acid were also purchased from Sigma-Aldrich.

The phytochemicals were obtained as follows. Chrysoeriol (1104S), 6-O-Me-luteolin (520-11-6), 7,4′-dihydroxyflavone (1259), datiscetin (1141S), eriodictyol (0056), flavonol (1026), homoeriodictyol (1118S), isorhamnetin-3G (1228), isorhamnetin (1120S), kaempferol-3G (1243G), luteolin-7G (1126S), quercetin-3G (0074), quercetagetin (1030), rhamnetin (1136S), tamarixetin (1140S), and tricetin (1335S) were obtained from Extrasynthese (Genay, France); 2,2′,4′-trihydroxychalcone (T502), 4,2′,5′-trihydroxychalcone (22-314), and gossypetin (G500) were purchased from INDOFINE Chemical Company Inc. (Hillsborough, NJ, USA). Flavone (16012-31), morin (23416-31), and pyrogallol (29703-52) were obtained from Nacalai Tesque Inc. (Kyoto, Japan). EGCG (E4268), hyperoside (00180585-25MG), and phloroglucinol (79330-25G) were purchased from Sigma-Aldrich (St. Louis, MO, USA); 1,2,4-trihydroxybenzene, daidzin, piceid, rutin, and tangeretin were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan); 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, cyanidin, hesperetin, and sudachitin were purchased from FUJIFILM Wako Pure Chemical Corporation. Zerumbone was obtained from Adipogen Life Sciences (San Diego, CA, USA). Other phytochemicals were from natural compound libraries (S990043-NAT1/NAT2) purchased from Sigma-Aldrich (St. Louis, MO, USA).

Tricetin was purchased from Extrasynthese (Genay, France). An 80-mM stock solution of Tricetin was made in dimethyl sulfoxide (DMSO) (Sigma-Aldrich, St. Louis, MO, USA) and stored at −20 °C. The final concentration of DMSO for all treatments was <0.5%. 2′,7′-Dichlorofluorescein diacetate (DCFDA), N-acetylcysteine (NAC), z-IETD-FMK (a caspase-8 inhibitor), zLEHD-FMK (a caspase-9 inhibitor), and a general inhibitor of caspases (zVAD-FMK) were purchased from Sigma-Aldrich. Antibodies against poly(ADP-ribose) polymerase (PARP), phosphorylated (p)-c-Jun N-terminal kinase (JNK), JNK1/2, p-extracellular signal-regulated kinase (ERK)1/2, caspase-9, caspase-3, and caspase-8 were purchased from Cell Signaling Technology (Beverly, MA, USA). Anti-p-p38, p38, and β-actin antibodies were obtained from BD Biosciences (San Jose, CA, USA).