Zhigancao, Glycyrrhizae Radix et Rhizoma Praeparata cum Melle, originates from the processed dried roots or rhizomes of Glycyrrhriza uralensis
Fisch., G. inflata
Bat., or G. glabra
L. (family Fabaceae). It is most frequently used in traditional Chinese medical formulary to harmonize all drugs and detoxify the adverse effects of herbs. Clinically, it treats disorders such as shortness of breath, fatigue, epigastria and abdominal pain, musculoskeletal and smooth muscle cramp and pain, and diarrhea [1
]. Due to the numerous bioactive compounds in it such as terpenoids, saponins, polysaccharides, and flavonoids, Zhigancao has been reported to possess anti-inflammatory activities [2
], antioxidative [3
], neuroprotective [5
], antiallergic [6
], anticonvulsant activities [7
], and so forth. Two chalcone derivatives in , isoliquiritin apioside (ILA) and isoliquiritin (IL), which are important ingredients in Zhigancao, are selected to research their pharmacokinetics. ILA has shown the pharmacological activity to reduce oxidative stress-induced genotoxicity [8
]. And IL has been reported to have shown various pharmacological activities such as antiangiogenic effect dependent upon antitube formation [9
], antidepressant-like effects in mice induced by forced swimming and tail suspension [10
], and inhibitory effects on tyrosinase [11
Isoliquiritin apioside (a) and isoliquiritin (b).
The bioavailability of drugs is the cornerstone for extending their in vitro biological functions to humans in vivo. The flavonoid glycosides show low oral bioavailability possibly because of the extensive conjugation of the free hydroxyl groups [12
] or/and glycosides hydrolysis to the aglycones in the intestinal lumen [14
]. The pharmacokinetic study of ILA and IL is essential for us to comprehend the bioavailability of two analytes after an oral administration of Zhigancao extrat.
To my knowledge, ILA and IL quantification method (LC-MS/MS) has been performed to study pharmacokinetics of multiple licorice flavonoids after an oral dose of Xiaochaihu-tang to rats [17
], but LC-MS/MS method is simply not available in most laboratories. In this study, we established the HPLC method which was highly selective and sensitive for simultaneous quantification of ILA and IL in rat plasma. The method was used to explore the possible pharmacokinetics of ILA and IL after an oral administration of Zhigancao extract.