Pyrogallol

Fresh grass carp was purchased from Rainbow mall (116°02′E, 28°67′N) in Nanchang, Jiangxi province, China. Alcalase and protamex were provided by Novozymes (Bagsvaerd, Denmark) and Ruiyang Biotechnology Co. Ltd (Jiangsu, China), respectively. Formic acid, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS), and trifluoroacetic acid (TFA) were purchased from Sigma‐Aldrich (Sigma, St. Louis, MO). Glutathiose (GSH), ferrozine, l‐glutathione reduced, pyrogallol, and other reagents were obtained from Solarbio (Beijing, China). Sephadex G‐25 was purchased from GE Healthcare (Pittsburgh, USA). Formic acid and TFA were of chromatographic grade, while other reagents were of analytic grade.

Pepsin, trypsin, bile salt, Pyrogallol, L(+)-ascorbic acid, Ferrous sulfate, potassium ferricyanide and trichloroacetic acid were purchased from Solarbio Science & Technology Co., Ltd. (Beijing, China). DMEM medium and special modified DMEM medium were obtained from Dalian Meilun Biotech Co., Ltd. (Dalian, China). RNA Isolation Kit was purchased from Vazyme Biotech Co., Ltd. (Nanjing, China). Fluorescent quantitation and a Reverse Transcription kit were obtained from United States Biological (Shanghai, China). ELISA kit was purchased from Chenglin Biotechnology Co., Ltd. (Beijing, China). DPP-IV was purchased from Sigma Chemical (St. Louis, MO, USA). All other chemicals and reagents were purchased from Beyotime Biotechnology Co., Ltd. (Shanghai, China).