Quantification of Anthraquinones, Stilbenes, and Phenolic Compounds

Commercial standards of derivatives of anthraquinones (aloe-emodin, aloe-emodin-8-Glu, emodin, emodin-8-Glu, rhein, rhein-8-Glu, chrysophanol, chrysophanol-8-Glu, physcion, sennoside-A, sennoside-B, sennoside-C, sennoside-D), stilbenes (resveratrol, pterostilbene, pinostilbene, piceatannol, astringin, polydatin, rhapontigenin, rhaponticin, isorhapontigenin, isorhaponticin, deoxyrhapontigenin, deoxyrhaponticin), phenolic acids (glucogallin, gallic-acid), flavones (vicenin-II, vicenin-III, apigenin-7-Glu), flavanones (pinocembrin, pinocembroside), chalcones (phloretin, phloridzin, trilobatin), and catechins (catechin, epicatechin, gallocatechin, procyanidin-B1, procyanidin-B2, procyanidin-B3, and procyanidin-C1), acetonitrile LC-MS grade, formic acid MS-grade, and tert-butanol were purchased from Merck (Darmstadt, Germany). Methanol, n-hexane, and n-butanol, all of analytical grade, were purchased from Fisher Chemical (Loughborough, UK). Ultrapure water was prepared using a Milli-Q water purification system (MerckMillipore). General reagents for bioassays were purchased from Sigma-Aldrich (a part of Merck KGaA, Darmstadt, Germany) and Cayman Chemicals (Ann Arbor, MI, USA). Reagents specific to cell culture, gene expression analyses, and cytokine profiling have been indicated below in the descriptions of the applied methods.