4 nitrophenyl α d glucopyranoside

Fresh pumpkin peel was obtained from Laiyang Mengyu Co., Ltd. (Yantai, China). CrCl₃·6H₂O (analytical grade) was obtained by Tianjin Kaitong chemical reagent Co., Ltd. (Shanghai, China). Trifluoroacetic acid (TFA) and insulin were provided by Sigma-Aldrich Co., Ltd. (St. Louis, MO, USA). α-Glucosidase, 4-nitrophenyl-α-D-glucopyranoside (PNPG), penicillin-streptomycin, and albumin bovine were purchased from Beijing Solarbio Technology Co., Ltd. (Beijing, China). Acarbose and monosaccharide standards (rhamnose, arabinose, galactose, glucose, mannose, xylose, fructose, galacturonic acid, and glucuronic acid) were obtained from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Sodium acetate, anhydrous (electrochemical grade), and SS254-500 sodium hydroxide solution were purchased from Thermo Fisher Scientific (Sunnyrale, CA, USA). High-glucose DMEM medium was obtained from Wuhan Servicebio Technology Co., Ltd. (Wuhan, China). Fetal bovine serum was purchased from Zhejiang Tianhang Biotechnology Co., Ltd. (Huzhou, China). Trivalent chromium standard solution was supplied by Beijing Century Aoke Biotechnology Co. Ltd. (Beijing, China). All other chemicals and reagents used were of analytical grade.

The fruiting bodies of Inonotus obliquus were purchased from the Sichuan Institute of Edible Fungi. Betulin and α-glucosidase were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). 4-Nitrophenyl-α-d-glucopyranoside (PNPG) and phosphate buffer solution (PBS) were purchased from Solarbio Technology Co., LTD (Beijing, China). Birch bark was purchased from the Birch Forest Factory of Changbai Mountain, in Jilin Province, China. All other chemicals and solvents were of analytical grade.