Caffeic acid

Aucubin, geniposidic acid, protocatechuic acid, chlorogenic acid, caffeic acid, geniposide, pinoresinol diglucoside, genipin, ferulic acid, liriodendrin, rutin, syringaresinol, quercetin, kaempferol from Weikeqi Biological Technology Co., Ltd. (Chengdu, China). All standards were identified with the purity higher than 98%. Methanol and formic acid of UPLC-MS grade were supplied by Fisher Scientific (Geel, Belglum).

Folin-Ciocalteureagent,gallic acid, catechinand otherpolyphenolicstandardswere purchasedfrom SichuanWeikeqiBiologicalTechnologyCo., Ltd. (China).1,1-Diphenyl-2-picrylhydrazyl(DPPH),2,2’-azinobis(3-ethyl-benzothiazoline-6-sulfonicacid)diammoniumsalt(ABTS),2,4,6-tris(2-pyridyl)-s-triazine(TPTZ),trolox,α-amylase,α-glucosidaseand 4-nitrophenyl-α-D-gluco-pyranoside(α-PNPG)wereobtainedfromSigma–Aldrich(USA).

Chicoric acid, caffeic acid, and caftaric acid (purity ≥ 98%) were purchased from Weikeqi Biological Technology Co., Ltd. (Sichuan, China). Bovine serum albumin (BSA), 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH), herring sperm DNA (hsDNA, D3159)

The reference standards of isorhmnetin (3), diosmetin (6), isochlorogenic acid A (7), kaempferol (10), quercetin (14), isochlorogenic acid C (15), apigenin (19), forsythin (20), chlorogenic acid (23), liquiritin (25), luteolin-7-O-glucoside (26), astragalin (28), luteolin (29), buddleoside (31), quercetin-3-O-glucoside (33), amygdalin (37), caffeic acid (38), forsythoside A (39), glycyrrhizic acid (40), ferulic acid (42), rutin (44), hyperoside (50), and platycodin D (51) were purchased from Sichuan Weikeqi Biological Technology, Co., Ltd. (Chengdu, China). Mulberry leaf, chrysanthemum, Fructus Forsythiae, licorice, Semen Armeniacae Amarum, Platycodi Radix and Phragmitis Rhizoma

Standard compounds including chlorogenic acid, caf-feic acid,p-hydroxycinnamic acid, hyperin, astragalin,quercetin, and kaempferol were procured from SichuanWeikeqiBiotechnological(purities>98.5%).Prednisolone,MS-222, DMSO, paraformaldehyde, and Alizarin RedS were purchased from Shanghai Aladdin Biochemi-cal Technology.

The reference standards ginkgolide M (3), apigenin-7-O-glucoside (7), bilobalide (8), ginkgolide C (9), quercetin (14), luteolin (15), apigenin (16), kaempferol (17), isorhamnetin (18), ferulic acid (19), ginkgolide A (20), myricetin (22), genistein (23), chlorogenic acid (24), caffeic acid (26), luteolin-7-O-glucoside (33), kaempferol-3-O-glucoside (34), kaempferol-7-O-glucoside (35), quercetin-7-O-rhamnoside (40), isoquercitrin (45) and rutin (65) were purchased from Sichuan Weikeqi Biological Technology Co., Ltd. (Chengdu, China), and their structures are shown in Fig. 1. Purities of all the reference standards were over 98% according to HPLC-DAD analysis.

Four batches of YHDP, each produced at a different time, were purchased from two different pharmaceutical companies in the market of mainland China. Four samples of YinHuang granules, one sample of YinHuang oral liquid and two samples of YinHuang lozenges were also purchased in mainland China for evaluation. The reference standards of chlorogenic acid (4) (L-007-131030), caffeic acid (6) (K-003-130501) and macranthoidin B (20) (H-014-130409) were purchased from Sichuan Weikeqi Biological Technology Co., LTD. (Sichuan, China).

Tseng and their structures were fully characterized by chemical and spectroscopic methods. The other standards, namely protocatechuic acid (3,4-DA, R3), rutin (R4), neochlorogenic acid (5-CQA, C1), chlorogenic acid (3-CQA, C2), cryptochlorogenic acid (4-CQA, C3), caffeic acid (CA, C4), isochlorogenic acid B (3,4-CQA, C5), isochlorogenic acid A (3,5-CQA, C6) and isochlorogenic acid C (4,5-CQA, C7) were purchased from the National Institute for Food and Drug Control (Beijing, China) or Sichuan Weikeqi Biological Technology Co., Ltd. (Qingjiang, Zhonglu, China) Purity analysis proved to be above 98% by HPLC, and their chemical structures are listed in Figure 7.

Caftaric acid was purchased from Shanghai Rongbo Biotechnologies Co. Gardenoside, caffeic acid, paeoniflorin, vitexin, naringenine and pinoresinol diglucoside were purchased from Sichuan Weikeqi Biological Technology Co. Azelaic acid, sodium orthavanadium, theophylline and forsythiaside were obtained from Shanghai Yuanye Bio-Technology Co.

Standards of chicoric acid, caffeic acid, and caftaric acid (purity ≥98%) were purchased from Weikeqi Biological Technology Co., Ltd (Sichuan, China). Rat liver microsomes were obtained from CHI Scientific, Inc. (Massachusetts, USA). Glucose-6-phosphate (G-6-P), G-6-P dehydrogenase (G-6-PD), β-nicotinamide adenine dinucleotide phosphate (NADP), 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)

Vanillic acid and caffeic acid (internal standard, IS) standards with the purity of ≥98% were purchased from Sichuan Weikeqi Biological Technology Co. Ltd (Chengdu, China).