Epigallocatechin gallate (egcg)

All chemicals were of analytical grade and purchased from Sigma-Aldrich, Inc. (St. Louis, MO, USA). Low molecular protein markers were procured from GE Healthcare (Chicago, IL, USA). Quercetin (3, 3′, 4′, 5, 7-pentahydroxyflavone) with a purity of >95% was acquired from Yuanye Biotechnology Co., Ltd. (Shanghai, China). Hyperoside (quercetin 3-O-galactoside) was acquired from Zelang Biological Technology Co., Ltd. (Nanjing, China). Catechin and EGCG were purchased from Chengdu Biopurify Phytochemicals Ltd. (Sichuan, China).

Aqueous extracts of various teas (TE), green (GTE), black (BTE) and oolong (OTE) were prepared as described 6. PPA (EC 3.2.1.1 A6255) was purchased from Sigma‐Aldrich Co. Ltd. (St. Louis, US). Pure phenolic compounds including tannic acid (TA), (+)‐catechin (C), (−)‐epicatechin (EC), (−)‐epigallocatechin (EGC), (−)‐epigallocatechingallate (EGCG), (−)‐epicatechingallate (ECG), theaflavin (TF), theaflavin‐3′‐gallate (TF1) and theaflavin‐3, 3′‐digallate (TF2) were obtained from Chengdu Biopurify Phytochemicals Ltd. (Chengdu, China). Other chemicals were of analytical grade.

Triphala oral liquids were manufactured by Sichuan Huamei Pharmaceutical Co., Ltd., and the batch number was 1601001. Water was purified using a Milli Q water purification system (Millipore, Bedford, MA, USA). HPLC-grade methanol was purchased from Fisher Chemical (Pittsburg, PA, USA). HPLC-grade formic acid was obtained from Chengdu Kelong Chemical Factory (Chengdu, China). Anhydrous ethanol (analytical purity) was also bought from Chengdu KeLong Chemical Factory (Chengdu, China). Standard of 1,1-diphenyl-2-picrylhydrazyl (DPPH BR 97%R1701) was purchased from Duly Biotech Co., Ltd. (Nanjing, China). Standards of gallic acid (GA, no.4051109), epigallocatechin (EGC, no.14051611), epicatechin gallate (ECG, no.14050602), corilagin (CR, no.PRF7102406), gallocatechin (GC, no.4051109), catechin (C, no.14051508), epigallocatechin gallate (EGCG, no.14121608), gallocatechin gallate (GCG, no.14102009), ellagic acid (EA, no.PRF7101305), chebulagic acid (CLA, no.CHB171222), and chebulic acid (CA, no.AP8070902) were purchased from Chengdu Biopurify Phytochemicals Ltd. (Chengdu, China). The purity of the 12 standards was each above 98.0%. Magnesium standard solution (no. GSB04-1735-2004), calcium standard solution (no. GSB-SCD-002-2013), and iron standard solution (no. GSB04-1742-2004) were all received from National Non-ferrous Metals and Electronic Materials Analysis and Testing Center.

The polyvinylidene fluoride fiber, MOF-1b, with an inner diameter of 0.5 mm and a pore size of 0.1 μm, was purchased from Tianjin Motianmo Engineering (Tianjin, China). XOD and hypoxanthine were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). Allopurinol was purchased from Shanghai Macklin Biotechnology Co., Ltd. Tris(hydroxymethyl) aminomethane (Tris) was purchased from Sangon Biotech Co., Ltd. (Shanghai, China). Dopamine was purchased from Aladdin Chemistry Co., Ltd. (Shanghai, China). Epicatechin, Epicatechin gallate, epigallocatechin, epigallocatechin gallate, quercetin, catechin, apigenin and puerarin were all purchased from Chengdu Biopurify Phytochemicals Ltd. (Chengdu, China). HPLC-grade methanol, acetonitrile and formic acid were obtained from Beijing InnoChem Science & Technology (Beijing, China). Water used for all the experiments was purified by a water purification system (ATSelem 1820A, Antesheng Environmental Protection Equipment, Chongqing, China). Unless specified otherwise, all the other chemicals and solvents, such as sodium chloride (NaCl) and hydrochloric acid (HCl), were all of analytical grade and purchased from Chengdu Chron Chemicals Co., Ltd. (Chengdu, China).