Isorhapontigenin

Fetal bovine serum (FBS), penicillin-streptomycin (PS), and Dulbecco’s modified Eagle’s medium (DMEM) were purchased from Invitrogen (Carlsbad, CA, USA). Trypsin EDTA was bought from Gibco (Waltham, MA, USA). Isorhapontigenin was purchased from Sigma Chemical (St. Louis, MO, USA). Enzyme-linked immune sorbent assay (ELISA) development kits, tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and interleukin (IL-1β) were acquired from R&D Systems (Minneapolis, MN, USA). The primary antibodies α-tubulin, β-tubulin, SPHK1, SPHK2, PARP, caspase-3, caspase-9, p38, pp38, JNK, pJNK, ERK, and pERK were purchased from Cell Signaling (Beverly, MA, USA). Secondary antibodies for Sirt1, Bax, Bcl2, cytochrome-C, and GAPDH were purchased from Santa Cruz Technology. MCF7, T47D, and MDA-MB-231 cells were purchased from the Korean Cell Line Bank. 3-[4,5-Dimethyl-2-thiazolyl]-2,5-diphenyl-2-tetrazolium bromide (MTT) powder, RNase-A, propidium iodide, and DCFDA were purchased from Sigma-Aldrich (St. Louis, MO, USA). The annexin V-FITC apoptosis detection kit and trypan blue were purchased from R and D Systems.

The stilbenoid derivatives to be tested (1–19, Table 1) were isolated from natural sources or obtained commercially. The naturally occurring stilbenoids trans-resveratrol (1), pinostilbene (2), thunalbene (3), piceatannol (4), piceatannol-3’-O-β-glucopyranoside (5), batatasin III (6), pinostilbenoside (7), 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyfenyl)-ethanone (10), 3,5-dimethoxystilbene (11), pterostilbene (15), pinosylvin monomethyl ether (17), and isorhapontigenin (18) were obtained from Sigma-Aldrich, synthetic compounds trans-stilbene (12), cis–stilbene (13), 4-stilbenecarboxylic acid (14), trans-α-methylstilbene (16), and 2,4,3´,5´-tetramethoxystilbene (19) were purchased from Sigma-Aldrich (Steinheim, Germany). The compounds 2-carboxyl-3-O-methyl-4´-β-d-glucopyranosyl-dihydroresveratrol (8) and 3-O-caffeoyl-(9→5)-β-apiosyl-(1→6)-β-glucopyranosyl-5,3´-O-dimethyldihydropiceatannol (9) were kindly provided by Dr. Sebastian Granica (Medical University of Warsaw, Warsaw, Poland) who had isolated them from Tragopogon tommasinii Sch.Bip. (Asteraceae, Cichorieae) [7 (link)].