Formic acid

Acetonitrile and formic acid, HPLC quality, were supplied by Labscan (Dublin, Ireland) and Acros Organic (Belgium), respectively. Protocatechuic acid, vanillic acid, syringic acid, caffeic acid, p-coumaric acid, 3-coumaric acid, ethyl gallate, 3,5,4’-trihydroxystilbene-3-O-β-d-glucoside (trans-piceid), (+)-catechin, (−)-epicatechin, epicatechin gallate, procyanidin B₁, procyanidin B₂, procyanidin B₃, quercetin-3-O-galactoside, quercetin-3-O-rutinoside, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, quercetin dihydrate, delphinidin-3-O-glucoside, cyanidin-3-O-glucoside and malvidin-3-O-glucoside were purchased from Extrasynthèse (Genay, France). Gallic acid, 4-hydroxybenzoic acid, trans-caftaric acid, trans-ferulic acid, ellagic acid, protocatechuic aldehyde, trans-resveratrol, 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), potassium persulfate, 2,2’-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 1 M phosphate buffer, fluorescein sodium and 2,2’-azobis(2-methylpropionamidine) dihydrochloride (AAPH) were obtained from Sigma-Aldrich (Madrid, Spain). Disodium carbonate, Folin–Ciocalteu reagent, methanol and ethanol were from Panreac (Barcelona, Spain).

Rice wine was purchased from the Pagoda Brand (Zhejiang Pagoda Brand; Shaoxing Rice Wine Co. Ltd., China; alcohol: 15%) and vinegar was purchased from the Amoy Brand (Amoy Food Ltd., Hong Kong; acetic acid: 5–8%).
Ferulic acid was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (China). The standard compounds of senkyunolide I, senkyunolide H, senkyunolide A, Z-ligustilide, and levistolide A were isolated from RC in our laboratory [28 (link)], and their structures were shown in Figure 1.Figure 1

Structures of the identified compounds in the fingerprints of the PRC samples.

The acetonitrile and formic acid used in the HPLC analysis were of HPLC grade and obtained from Lab-scan (Thailand). The methanol used for the sample extraction was of analysis grade and also purchased from Lab-scan (Thailand). Deionized water was generated using a Milli-Q water purification system (Millipore, USA).