Identification and Quantification of “Quality Markers” in Tongkang Tablet on Recurrent Respiratory Tract Infections (RRTIs) by UFLC-IT-TOF–MS/MS and HPLC–DAD

Recurrent respiratory tract infections (RRTIs) is one of the most common diseases in children and adolescents, especially for preschool children. Tongkang tablet (TKT), a traditional Chinese medical formula consisting of Astragali Radix (AR), Atractylodes Macrocephala (AM), Saposhnikovia Divaricata (SD), Rhizoma Dioscoreae (RD), Concha Ostreae (CO), and Pericarpium Citri Reticulatae (PCR), has been widely used to treat recurrent upper respiratory tract infections of children. To ensure the efficacy and safety of TKT, an integrative and reliable quality control method is urgently needed. The concept of quality marker (Q-marker) is highly helpful but the selection and quantitation of appropriate Q-markers remains challenging, especially for the complex components of Chinese medicinal products. The aim of this article was to identify and quantify Q-markers of TKT for the establishment of a quality control method. First, by a validated UFLC-IT-TOF–MS/MS method, a total of 40 compounds were unambiguously or tentatively identified, including 21 flavonoids, 10 chromones, 3 coumarins, 3 sesquiterpenes, 2 batatasins and 1 saponin. Among them, 10 compounds were further confirmed by reference standards. Then, 10 compounds, including calycosin-7-O-glucoside, prim-O-glucosylcimifugin, cimifugin, naringin, 4′-O-D-glucosyl-5-O-methylvisamminol, hesperidin, ononin, calycosin, sec-O-glucosyhamaudol and formononetin, were selected as Q-markers based on the knowledge of absorption characteristics and bio-activity with the reference literatures. Finally, based on the 10 Q-markers, the fingerprint chromatography was established by HPLC–DAD method, which proved accurate, sensitive and reliable. The presently developed method based on 10 Q-markers is expected to lay a good foundation for the quality control of TKT.