Abstract: The in vitro antioxidant capacity of Lactobacillus bulgaricus A105 and Bifidobacterium animalis B211 were evaluated by adding 0.25 mg/mL lotus leaf flavonoids into the culture medium during growth.The cell lysis solution was extracted and the antioxidant activities were analyzed through radical scavenging ability and inhibition effect on lipid preoxidation.The results showed that 0.25 mg/mL of lotus leaf flavonoids can improve the O₂^-· scavenging activity of B.animalis (54.9%) and L.bulgaricus (14.8%) in vitro. Also,lotus leaf flavonoids have a slight increasing effect on the DPPH radical ability on L.bulgaricus while a slight inhibition effect on B.animalis. It can significantly improve the anti-lipid peroxidation activity of L.Bulgaricus, the increasing rate reached to 658%,which showed obvious synergistic effect.In addition,it can significantly improve intracellular enzyme activity of superoxide dismutase (SOD) and glutathione (GSH) vitality in B.animalis and L.bulgaricus. In conclusion,lotus leaf flavonoids had synergistic effects on the antioxidant activity of B.animalis and L.bulgaricus. All those results showed the addition of lotus leaf flavonoids had some promoting effects on the antioxidant activities of B.animalis and L.bulgaricus, especially high synergistic effect on anti-lipid peroxidation activity of L.bulgaricus, which was possibly caused by increasing SOD and GSH activities with the addition of lotus leaf flavonoids.

Key words: lotus leaf flavonoid, probiotics, antioxidant capacity, synergistic effect