Isoferulic acid

Epicatechin, kaempferol, quercetin, rutin, isoquercitrin, syringic acid, p-coumaric acid, chlorogenic acid, cryptochlorogenic acid, caffeic acid, ferulic acid and gallic acid were purchased from Adamas Reagent, Ltd. (Shanghai, China). Other standard reference materials including 4-methoxysalicylic acid, p-hydroxycinnamic acid, isoferulic acid, 1,3-dicaffeoylquinic acid, gentiopicrin, grosvenorine, diosmin, isorhamnetin and baicalein were obtained from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine (TPTZ), 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 4-nitrophenyl α-D-glucopyranoside (p-NPG) were all obtained from Adamas Reagent, Ltd. (Shanghai, China). Acetonitrile and formic acid (99.9%, HPLC grade) were obtained from Thermo Fisher Scientific (Waltham, MA, USA). Cellulase (400 u/mg) from Trichoderma Vride G, hemiCellulase (20,000 u/g) and pectinase (500 u/mg) from Aspergillus niger were all supplied from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). All other reagents and chemicals used in this study are analytical grade.

The organic acid standards (L-tartaric acid, lactic acid, malic acid, acetic acid, etc.), as well as polyphenol standards (protocatechuic acid, p-hydroxybenzonic acid, chlorogenic acid, vanillic acid, (-)-epigallocatechin gallate, epicatechin, vanillin, p-coumaric acid, (-)-epicatechin gallate, isoferulic acid, etc.), were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Water was purified using a Milli-Q system from Millipore (Bedford, MA, USA).
Isoamyl ethanoate, benzylcarbinyl acetate, isobutyl acetate, butyl acetate, propyl acetate, hexyl acetate β-damascenone, naphthalene, cinnamene, linalool, citronellol, d-limonene, α-terpineol, nerol oxide, ethyl dodecylate, ethyl heptoate, ethyl caproate, ethyl butanoate, ethyl caprylate, ethyl propanoate, ethyl isobutyrate, ethyl n-valerate, etc., were provided by Sigma-Aldrich (Shanghai, China). The internal standard of 4-methyl-1-pentanol was obtained from Tokyo Chemical Industry Co. Ltd. (Tokyo, Japan). The calculation of retention indices (RIs) was used with n-alkanes (C8-C40) purchased from Supelco (Bellefonte, PA, USA).

S-adenosyl-_L-methionine (SAM) was purchased from Shenggong (Shanghai, China). Gallic acid, EC, (−)-epigallocatechin, ECG, and EGCG were purchased from Sigma-Aldrich (St. Louis, MO, USA). ECG3″Me, ECG4″Me, EGCG3″Me, and EGCG4″Me, were purchased from Nagara Science Co., Ltd. (Gifu, Japan). Myricetin and tamarixetin were obtained from BioBioPha Co., Ltd (Kunming, China), and caffeic acid, ferulic acid, isoferulic acid, 3-O-MethylGallic acid, 4-O-MethylGallic acid, methyl gallate, methyl 4-O-methylgallate, cyanidin 3-O galactoside chloride, peonidin 3-O-galactoside chloride, isoquercitrin, isorhamnetin 3-O-glucoside and syringetin were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Mearnsetin and laricitrin were from ChemFaces (Wuhan, China). Methyl 3-O-methylgallate was from MedChemExpress (Monmouth Junction, NJ, USA). Myricetin 3′, 4′-dimethyl ether was provided by Prof. Ai-Xia Chen of Shandong University, China.