Flavonoids of Lotus (Nelumbo nucifera) Seed Embryos and Their Antioxidant Potential

Flavonoids from lotus (Nelumbo nucifera) seed embryos were fractionated over a macroporous resin chromatography into 2 main fractions (I and II), and subsequently identified by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS2). Sixteen flavonoids were identified in lotus seed embryos, including 8 flavonoid C-glycosides and 8 flavonoid O-glycosides, in which the flavonoid C-glycosides were the main flavonoids. Among them, 2 flavonoid O-glycosides (luteolin 7-O-neohesperidoside and kaempferol 7-O-glucoside) were identified in lotus seed embryos for the 1st time. For further elucidating the effects of flavonoid C-glycosides to the bioactivities of lotus seed embryos, we compared the differences of the flavonoids and their antioxidant activities between leaves and seed embryos of lotus using the same methods. The results showed the antioxidant activity of flavonoids in lotus seed embryos was comparable or higher than that in lotus leaves, whereas the total flavonoid content in seed embryos was lower than lotus leaves which only contained flavonoid O-glycosides. The flavonoid C-glycosides of lotus seed embryos had higher antioxidant properties than the flavonoid O-glycosides presented in lotus leaves. This study suggested that the lotus seed embryos could be promising sources with antioxidant activity and used as dietary supplements for health promotion.