Ligustilide

The Chengdu Kelong Chemical Reagent Factory, located in Chengdu, Sichuan, China, supplied the analytical-grade ethyl acetate, ethyl ether and methanol. The analytical-grade copper sulfate pentahydrate (CuSO₄·5H₂O) was sourced from the Shanghai Chemical Reagent Factory located in Putuo District, Shanghai, China. Ligustilide, with a purity of at least 98%, came from Chengdu Herbpurify Co., LTD located in Chengdu, Sichuan, China. Both quercetin and ferulic acid, with a purity level of not less than 99%, were acquired from Shanghai EkearBiotech. Co., Ltd. located in Fengxian District, Shanghai, China. Sigma-Aldrich Co., LLC, based in St. Louis, MO, USA, provided catechin, kaempferol and heparin sodium, each boasting a purity of 99% or higher. Every other chemical used for this research met the analytical-grade criteria.

Standard compounds of albiflorin, paeoniflorin, ferulic acid, senkyunolide I, quercetin, isoliquiritigenin, atractylenolide III, ligustilide, atractylenolide II, liquiritin, liquiritigenin, saikosaponin c, glycyrrhizic acid, saikosaponin a and naringenin as an internal standard (IS) (≥98% purity) were purchased from Chengdu Herbpurify Co., Ltd. (Chengdu, China). The structures of these compounds are shown in Figure 3.
Acetonitrile (HPLC grade) was purchased from Fisher (Fair Lawn, NJ, USA). Ultrapure water with a sensitivity of 18.2 W was prepared from a Milli-Q water purification system (Millipore, Billerica, MA, USA). All other chemicals were analytical grade.