Saikosaponin a

For sample extraction, ethanol, methanol, and ethyl acetate (extra-pure-grade) were purchased from Duksan Pure Chemicals Co. (Ansan, Republic of Korea). For high-performance liquid chromatography (HPLC) quantification, HPLC-grade acetonitrile, methanol, and water were purchased from Thermo Fisher Scientific (Waltham, MA, USA). Formic acid (99%, HPLC-grade) was obtained from Wako Pure Chemical Industries Ltd. (Osaka, Japan), and acetic acid (99%) and LPS (from Escherichia coli O111:B4, L4391) were provided by Sigma-Aldrich (St. Louis, MO, USA). Glycyrrhizic acid (CAS No. 1405-86-3, CFN99151, CFS202002, purity 99.5%), ginsenoside Rb₁ (CAS No. 41753-43-9, CFN99964, CFS202101, purity 98.9%), baicalin (CAS No. 21967-47-9, CFN99111, CFS202003, purity 98.0%), saikosaponin A (CAS no. 20736-09-8, CFN99987, CFS202102, purity 99.4%), and saikosaponin B2 (CAS No. 58316-41-9, CFN99126, CFS202102, purity 99.7%) were supplied by Chemfaces (Wuhan, China). Antibodies against NOS2 (iNOS), COX-2, p38, phosphorylated-p38 (pp38), ERK, phosphorylated-ERK (pERK), JNK, phosphorylated-JNK (pJNK), NRF2, β-actin, anti-rabbit and anti-mouse IgG HRP-linked antibodies were purchased from Cell Signaling Technology (Danvers, MA, USA) and Santa Cruz Biotechnology (Santa Cruz, CA, USA).

All analytical experiments were conducted with the Shimadzu LC-20AD XR High Performance Liquid Chromatography (HPLC) system and an SPD-M20A Photo Diode Array (PDA) detector (Kyoto, Japan). Acetonitrile and ethanol were obtained from J.T. Baker (PA, United States), and 18.2 MΩ distilled water was purified using Younglin’s Aqua Max Ultra 370 (Anyang, South Korea) series. Geniposide, paeoniflorin, tilianin, paeonol, eugenol, saikosaponin A, ligustilide and decursin reference compounds were used for HPLC analysis and all were purchased from ChemFaces (Hubei, China).