Isoimperatorin

Methanol (99.8%), n-hexane (95.0%), ethyl acetate (99.5%), and magnesium chloride hexahydrate (98.0%) were obtained from Duksan (Ansan, Republic of Korea), formic acid (99.0%) from Daejung Chemicals & Metals (Siheung, Republic of Korea), and toluene (99.5%) from Junsei Chemical Co., Ltd. (Tokyo, Japan). Water (HPLC grade), Methanol (HPLC grade), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were obtained from Thermo Fisher Scientific (Waltham, MA, USA). Standard compounds, oxypeucedanin (98.3%, CFN90350-CFS202201), imperatorin (98.4%, CFN98758-CFS202301), isoimperatorin (98.1%, CFN99107-CFS202201), byakangelicol (99.1%, CFN98167-CFS202301), byakangelicin (99.4%, CFN98152-CFS202201), suberosin (98.8%, CFN98985-CFS202201), and falcarindiol (99.4%, CFN98220-CFS202301) were supplied by Chemfaces (Wuhan, China), xanthotoxin (98.0%, LOT AS01) from TCI (Tokyo, Japan), 2-linoleoyl glycerol (95.0%) from Glpbio (Montclair, NJ, USA), and thymol (98.5%) from Merck (Darmstadt, Germany). Individual standards were dissolved in Methanol to create solution stocks with a concentration of 1.0 mg/mL.

Imperatorin, isoImperatorin, and oxypeucedanin were purchased from ChemFaces (Wuhan, China; Figure 5). Warfarin as an IS, formic acid, ethanol, and TNBS were obtained from Sigma-Aldrich (St. Louis, MO, USA). “MS-grade” water and acetonitrile (Fischer Scientific, Loughborough, UK) were used for the MS analysis and plasma preparation. Raw ADR material was purchased from a local herb market (Yeongcheon, Korea) and stored in the herbarium (registration number #58) of the KM Application Center at the Korea Institute of Oriental Medicine. An ethanolic extract of ADR, a lyophilized brownish power, was prepared according to Jeong et al. [27 (link)]. The oxypeucedanin, Imperatorin, and isoImperatorin contents in ADR were 6.67, 2.34, and 0.99 mg/g extract, respectively.

HPLC analysis was carried out as previously described [27 (link)] on a liquid chromatograph (LaChrom Elite, Hitachi, Tokyo, Japan) using DAD detection (200–400 nm). Quantification was carried out at two wavelengths (λ): 254 and 330 nm.
Reference substances were obtained from bergapten, imperatorin, xanthotoxin, and psoralen from Roth (Karlsruhe, Germany); 5,7-dimethoxycoumarin, 4-hydroxy-6-methylcoumarin, 6-methylcoumarin, osthole, and umbelliferone from Sigma-Aldrich (St Louis, MO, USA); coumarin and scopoletin from Fluka (Bucha, Switzerland); 4-methylumbelliferone, 4,6-dimethoxy-2H-1-benzopyran-2-one, and skimmianine from ChromaDex (Irvine, CA, USA); and isopimpinellin, isoimperatorin, daphnetin 7-methyl ether, rutaretin, daphnetin, osthenol, bergaptol, daphnetin dimethyl ether, γ-fagarine, and 7-isopentenyloxy-γ-fagarine from ChemFaces (Wuhan, China).