Chemical Constituents Comparison Between the Flowers of Sophora japonica L. and Robinia pseudoacacia L. by UPLC-Q-TOF-MS/MS and HPLC

The flowers of Sophora japonica L. (SJF) and Robinia pseudoacacia L. (RPF) are edible and similar in appearance. The chemical constituents of SJF and RPF were compared by UPLC-Q-TOF-MS/MS and HPLC analysis in this study. A total of 29 and 19 constituents were identified in SJF and RPF, respectively. Flavonoid glycosides were the main constituents found in both flowers. The main aglycon moieties found in SJF were quercetin, kaempferol and isorhamnetin, whereas acacetin and kaempferol were the main ones found in RPF. Additionally, the content of flavonoids in SJF was significantly higher than that in RPF, as determined by HPLC. Rutin was the most dominant flavonoid in SJF with a content range of 72.31~88.15 mg/g, followed by quercetin (13.05~20.30 mg/g). Kaempferol-di(rhamnoside)-hexoside was the most dominant flavonoid in RPF with a content range of 25.94~30.00 mg/g. The distinct flavonoid profiles indicated the chemical non-equivalence of SJF and RPF. Therefore, RPF should not be considered a direct substitute for SJF in herbal medicine without further pharmacological and clinical validation.