Separation and preparation of the main flavonoids in Flos Dolichoris Lablab and their antioxidant activity

Flos Dolichoris Lablab, as a flower of a homologous plant with medicinal and food applications, has rich plant activity with research value. In this article, we studied flavonoids in Flos Dolichoris Lablab, and an effective semipreparative HPLC separation method was established. Then, seven flavonoids from Flos Dolichoris Lablab were prepared in one step, and their antioxidant activity was evaluated. The results show for the first time that the seven flavonoids kaempferol 3-O-sophoroside (1), quercetin 3-rutinoside (2), quercetin 3-glucoside (3), kaempferol-3-O-robinobioside (4), kaempferol-3-O-rutinoside (5), isorhamnetin 3-O-neohesperidoside (6), and kaempferol-3-O-galactoside (7) were isolated from the genus Lablab. Antioxidant activity results with individual compounds show that compounds 2, 3, and 7 exhibit better antioxidant activity. Experiments on different combinations of flavonoids of Flos Dolichoris Lablab indicate that the interaction of flavonoids can affect the mixture's total antioxidant activity. This research provides guidelines for preparing flavonoids present in Flos Dolichoris Lablab and structure-activity relationship studies.