Metabolite identification and quantification:

The sample extracts were analyzed using an LC-ESI-MS/MS system (HPLC, Shim-pack UFLC SHIMADZU CBM30A system, www.shimadzu.com.cn/; MS, Applied Biosystems 6500 Q TRAP, www.appliedbiosystems.com.cn/). The HPLC effluent was alternatively connected to an electrospray ionization (ESI)-triple quadrupole-linear ion trap–MS/MS system (Applied Biosystems 4500 Q TRAP). The analytical conditions were following as Chen et al. [26]. Metabolite identification was based on the MWDB (http://www.metware.cn/), following their standard metabolic operating procedures. Metabolite quantification was carried out using multiple-reaction monitoring (MRM) [26].