Protocatechuic acid

Dexamethasone was obtained from Beijing Solarbia Technology Co., Ltd. (Beijing, China). IL-6, IL-1β, TNF-α enzyme-linked immunosorbent assay (ELISA) and arginase-1 (Arg-1) ELISA kit was obtained from Shanghai Enzymatic Union Biotechnology Co., Ltd. (Shanghai, China). Inducible nitric oxide synthase (iNOS) and bicinchoninic acid (BCA) protein concentration assay kits were purchased from Nanjing Jiancheng Biological Engineering Institute (Nanjing, China). CD86 polyclonal antibody and CD206 polyclonal antibody were purchased from Proteintech Group, Inc. (Wuhang, China). Poly(I:C) and reference standards of chlorogenic acid, forsythoside A, liquiritin, saikosaponin A, baicalin, arginine, magnolol, protocatechuic acid, 4-hydroxyacetophenone, aristolochic acid A and artemisinin were obtained from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). All herbs used to prepare QWJR were obtained from Sinopharm Yunnan, Ltd. (Kunming, China).

All the Chinese herbs were provided by Tongde Hospital of Zhejiang Province (Hangzhou, China). All the chemical standards, including l (+)-arginine, proline, adenine, succinic acid, isoleucine, leucine, gallic acid, phenylalanine, protocatechuic acid, l-tryptophan, protocatechuic aldehyde, neo-mangiferin, chlorogenic acid, caffeic acid, amygdalin, mangiferin, rutin, liquiritin, luteoloside, naringin, berberrubine, baicalin, quercetin, epimedin A, epimedin B, epimedin C, icarrin, isorhamnetin, glycyrrhizic acid, limonin, aaikosaponin A, and 3-N-butyl-4,4-dihydrophthalide, were purchased from Shanghai Yuanye Bio-Technology Co. Ltd (Shanghai, China). Azoxymethane (AOM) was obtained from Sigma-Aldrich (St. Louis, MO, United States) and dextran sodium sulfate (DSS) from MP Biomedicals (Santa Ana, CA United States). TUNEL apoptosis assay kits, radioimmunoprecipitation assay (RIPA) buffer, BCA protein assay kits, and anti-MMP9 antibody (AF5234) were purchased from Beyotime (Beijing, China). Mouse IL-6 and IL-17A ELISA kits were from LiankeBio (Hangzhou, China), and antibodies to p-STAT3 (AF3293), STAT3 (AF6294), NF-κB-p65 (BF8005), Bcl-2 (BF9103), Lamin B (AF5161), and β-actin (T0022) were purchased from Affinity Biosciences (Changzhou, China). Antibodies to IL-17RA (sc-376374) and Bax (sc-20067) were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, United States).

The standards of procyanidin B2 (5), daidzin (7), dihydroquercetin (8), genistin (9), liquiritigenin (12), calycosin (14), naringenin (15), genistein (16), medicarpin (20), prunetin (21) and biochanin A (22) were purchased from Nanjing Liangwei biotechnology Co., Ltd. (Nanjing, China). Epicatechin (6), rutin (10), kaempferol (17) and formononetin (19) were purchased from the Chinese National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China). Ononin (11), gallocatechin (1), epigallocatechin (3) and isoliquiritigenin (18) were purchased from Chengdu Chroma Biotechnology Co., Ltd. (Chengdu, China). Daidzein (13) and protocatechuic acid (2) were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). Catechin (4) was purchased from Baoji Chenguang Biotechnology Co., Ltd. (Baoji, China). The purities of all compounds were greater than 98%, checked by HPLC analysis. The structures of the 22 standards were shown in Figure S1. Formic acid, acetonitrile and methanol of HPLC grade were purchased from Merck (Darmstadt, Germany). Chloroform was HPLC pure and purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd. (Shanghai, China). Ultrapure water was prepared using a Milli–Q water purification system (Millipore, Bedford, MA, USA).

2,3,5-Triphenyltetrazolium chloride (TTC) and 5-bromo-2′-deoxyuridine (BrdU) were purchased from Sigma Chemical Co. Tanshinol, ferulic acid (FA), baicalin, protocatechuic acid, rosmarinic acid, salvianolic acid B, hydroxysafflor yellow A and 9′-methyl lithospermate B were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Rabbit monoclonal Bax antibody (#14796s, 1:1000), rabbit monoclonal IL-1β antibody (#12426s, 1:1000), rabbit monoclonal IL-6 antibody (#12912p, 1:1000) were purchased from Cell Signal Technology. Mouse monoclonal TNF antibody (#60291-1-Ig, 1:500), rabbit polyclonal BDNF antibody (#25699-1-AP, 1:200), and mouse β-actin antibody (#60008-1-Ig, 1:4000) were purchased from Proteintech Group, Inc., and rabbit polyclonal Bcl-2 antibody (#bs-0032R, 1:100) was purchased from Bioss (Beijing).

Dried FSI (sun dried with the water content of 8.0 ± 0.5%) was purchased from Hebei Anguo Yao Yuan Trading Co., Ltd. (Baoding, China). Rutin (RU), quercetin (QU), hyperoside (HY), quercitrin (QI), kaempferol (KA), gentianoside, protocatechuic acid, isorhamnetin, kaempferol-3-O-Rutinoside, narcissoside, chlorogenic acid, 4-nitrophenyl β-D-glucopyranoside (PNPG), acarbose, α-glucosidase (Yeast) (100 U/mg) and all chemicals were obtained from Shanghai Yuan Ye Biological Technology Co., Ltd. (Shanghai, China).

Protocatechuic acid (≥ 98%) was provided by Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). LPS (Escherichia coli Serotype O55:B5) was purchased from Sigma-Aldrich (St. Louis, MO, USA). Antibodies against occludin, claudin-1, ZO-1, and corresponding secondary antibodies were purchased from Proteintech Group, Inc. (Chicago, IL, USA). Aureomycin (AUR) and ingredients for basal diet were provided by Hunan Liuyanghe Feedstuff Co., Ltd. (Changsha, Hunan, China).