Glucoerucin

All chemicals and solvents used during extraction and analysis were of analytical grade and purchased from Fisher Scientific Korea Ltd. (Seoul, South Korea) and Sigma-Aldrich (St. Louis, MO, USA). GSL standards (gluconapin, glucobrassicanapin, progoitrin, glucotropaeolin, glucoerucin, gluconasturtiin, glucoberteroin, and glucobrassicin) were purchased from Phytoplan Diehm & Neuberger GmbH (Heidelberg, Germany). All individual GSL standards had purity greater than or equal to 97%.

The standards of sinapic and caffeoylquinic acids were purchased from Sigma-Aldrich (Steinheim, Germany). The standards of glucoraphanin, glucoerucin, glucoiberin, glucobrassicin, hydroxyl-glucobrassicin, gluconasturtiin, methoxy-glucobrassicin, neoglubobrassicin, 3,4-diindolylmethane, and iberin (GR, GE, GI, GB, HO-GB, PE, MeOH-GB, NeoGB, SFN, I3C, and DIM, respectively) were purchased from Phytoplan GmbH (Heidelberg, Germany). The standards of sulforaphane, iberin, and indole-3-carbinol (SFN, IB, and I3C, respectively) were obtained from Santa Cruz Biotechnology (Dallas, US), Biorbyt LTD (Cambridge, UK), and LKT Laboratories (St. Paul, MN, USA), correspondingly. Acetic and hydrochloric acids, as well as ammonium acetate, were from Panreac labs (Barcelona, Spain). Methanol for hydromethanolic extractions and acetonitrile and acetic acid grade solvents for LC-MS were supplied by J.T. Baker (Philipsburg, NJ, USA). All water employed in the extraction and the chromatographic analysis was purified by using a Milli-Q system (Millipore, Bedford, MA, USA).

Myrosinase, sinigrin, and rapeseed standard reference material of known glucosinolate composition were obtained from Sigma Aldrich (Steinheim, Germany). Glucoraphanin and glucotropaeolin were obtained from Phytoplan (Heidelberg, Germany), while sinalbin was isolated from the seeds of Sinapis alba L., and glucoerucin from Eruca vesicaria (L.) Cav. All other chemicals and reagents were of an analytical grade. Cancer cell lines (human bladder cancer cell line T24 and TCCSUP) were cultured in a humidified atmosphere with 5% CO₂ at 37 °C, in a Dulbecco’s modified Eagle’s medium (DMEM, EuroClone, Milano, Italy) containing 4.5 g/L glucose, 10% fetal bovine serum (FBS), and 1% antibiotics (Penicillin Streptomycin, EuroClone, Milano, Italy).