Psoralen

HPLC-grade methanol was purchased from Merck KGaA (Darmstadt,Germany). HPLC-grade formic acid was purchased from Macklin Bio-chemical Co., Ltd. (Shanghai, China). Ultra-pure water was purchasedfrom Watsons Company (China). All other reagents were of analyticalgrade.  The  reference  standards,  such  as  adenine,  scopoletin,mangiferin,  isofraxidin,  scoparone,  paeonol,  psoralen,  daidzein,arteannuin B, casticin, artemetin, and piperine, were purchased fromSichuan Weikeqi Biological Technology Co., Ltd. (China).

Fifteen standard compounds (psoralen, isopsoralen, corylifolin, corylifolinin, psoralidin, xanthotoxin, bergapten, osthole, imperatorin, aconitine, hypaconitine, mesaconitine, benzoylaconine, benzoylhypaconine, and benzoylmesaconitine; Figure 1), were purchased from Weikeqi Biological Technology Co., Ltd. (Chengdu, China). The purities of the compounds were >98% as determined by high-performance liquid chromatography (HPLC). The stock solution of each standard was prepared at a concentration of 1 mg/mL in 50% MeOH and stored at ?80°C until use.

The herbarium voucher specimens were deposited in the Institute of Chinese Traditional Surgery, Longhua Hospital affiliated to Shanghai University of Traditional Chinese Medicine, with voucher numbers BGZ-1207081 (Psoraleae Fructus), SCZ-1207082 (Cnidii Fructus), and FZ-1207083 (Aconiti Lateralis Radix Praeparata). The reference standards of psoralen, isopsoralen, xanthotoxin, bergapten, osthole, and imperatorin (purity > 98%) were purchased from Sichuan WeiKeqi Biological Technology Co., Ltd. (Chengdu, China). The chemical structures of these compounds are shown in Fig. 1. Tolbutamide (internal standard, IS), with purity higher than 98%, was obtained from Sigma-Aldrich Co. LLC (St. Louis, Missouri, USA).