Liquiritin

IL-6 was procured from Sigma. Antibodies to occludin, ZO-1, claudin-2, MLC-2, and MLCK were purchased from Zymed Laboratories; the other antibodies were purchased from cell signaling. Alexa 594 secondary antibodies and DAPI (4#,6#-diamidino-2-phenylindole) were purchased from Molecular Probes. SYBR-Green PCR Master Mix is ABI (catalog number 43049155; Applied Biosystems). The standard of liquiritin was purchased from Sigma-Aldrich (St. Louis, MO, USA). Nodakenin, quercitrin, arctiin, matairesinol, and icariin were purchased from Chemfaces (Hubei, China). Arctigenin was purchased from MUST (Chengdu Must Bio-Technology Co., Ltd., Chengdu, China). Angoroside C, neolicuroside, (8S, 8′′R)-8-(4-hydroxy-3-methoxybenzyl)-8′′-(3′,4′-dimethoxybenzyl)-γ-butyrolactone 4-O-(β-D-glycopyranoside), and emodin 8-O-β-D-glucopyranoside 8 were obtained from Chungnam National University (Daejeon, Korea). The purity of the standards was all above 95%. HPLC grade acetonitrile was purchased from J. T. Baker Inc. (Philipsburg, NJ, USA) and acetic acid purchased from JUNSEI (Junsie Chemical Co., Ltd., Tokyo, Japan). Ultrapure water was prepared by Puris-Evo-UP Water System with Evo-UP Dio VFT and Evo-ROP Dico20 (Mirae ST Co., Ltd., Anyang, Gyeonggi-do, Korea). Ultrapure water (UW) was prepared with a resistivity of 18.2 MΩ cm⁻¹ (Puris, Esse-UP Water System, Mirae ST Co., Anyang, Korea).

Monacolin K, citrinin, liquiritin, liquiritigenin, trifluoroacetic acid, acetic acid, and p-nitrophenyl-β-D-glucopyranoside were purchased from Sigma-Aldrich Co. (USA), isoliquiritin and isoliquiritigenin from ChemFaces (China), and liquiritin apioside and isoliquiritin apioside from Chengdu Biopurify Phytochemicals Ltd. (China). All HPLC-grade solvents were purchased from Fisher Scientific Korea Ltd. (Korea). Extraction solution and methanol were purchased from Samchun Pure Chemical (Korea). Potato dextrose agar (PDA) was purchased from Acumedia Inc.(USA), and glucose from Duksan Pure Chemicals (Korea). Yeast extract-peptone-dextrose and yeast nitrogen base media were purchased from Sigma-Aldrich Co. G. uralensis base media were composed of 2.0 5.0% G. uralensis extracts and 2% glucose. Licorice (G. uralensis) was purchased from a regional market in Chungcheongbuk-do, Korea. Licorice extracts were prepared by adding 5 L of distilled water to 1.2 kg of licorice, followed by boiling at 95oC for 5 h. The extraction supernatant recovered by filtration with a Whatman filter paper No. 1 (UK) was concentrated to a solid content of 15% using a vacuum evaporator.

Ultra-pure water (18 mΩ) was obtained from a Milli-Q water purification system (Millipore Co., Ltd., Milford, MA, USA). High-performance liquid chromatography (HPLC)-grade methanol, acetic acid, and 56 analytical standards, including catechinic, scopolin, chlorogenic acid, epicatechinic, vanillic acid, caffeic acid, purerarin, syringic acid, daidzin, glycitin, scopoletin, eriocitrin, umbelliferone, p-coumaric acid, dihydroquercetin, sinapic acid, genistin, liquiritin, ferulic acid, salicylic acid, rutin, isoferulic acid, m-coumaric acid, naringin, hesperidin, resveratrol, xanthotoxol, silydianin, sinapyl alcohol, o-coumaric acid, liquiritigenin, kaempferol, 2’-hydroxygenistein, eriodictyol, daidzein, psoralen, glycitein, quercetin, didymin, bergaptol, naringenin, luteolin, cinnamic_acid, hesperetin, genistein, bergapten, diosmetin, isoliquiritigenin, coumestrol, sinensetin, formononetin, medicarpin, imperatorin, biochanin A, tangeretin, and rotenone (displayed in Table S2), were purchased from Sigma-Aldrich Co., Ltd. The stock solutions of these authentic standards were 10.0 mg of each standard dissolved in 10 mL methanol. Then, the stock solutions were diluted to various concentrations before analysis. All stock solutions were sealed with Parafilm^® and stored in a −20 °C freezer.