Abstract: 【Objective】 This study was carried out to explore the intervention effect of N-butanol fraction of Polygonum hydropiper flavonoids (FNB) on oxidative stress in porcine lung-cell alveolar macrophages (3D4/2 cells) infected with Pseudoabies virus (PRV) in vitro, aiming to preliminarily explore and analyze the antioxidant effect and mechanism of FNB.【Method】 Porcine kidney cells (PK15 cells) were infected in vitro with PRV from 10^-10 to 10^-1 concentrations, and TCID₅₀ was calculated.The 3D4/2 cells were divided into BC, DMSO, PRV, FNB1, FNB2 and FNB3 groups. BC group was treated with DMEM medium only.The remain groups were treated with PRV which multiplicity of infection (MOI) was 0.1, after incubation for 2 h, DMEM medium was added to PRV group. DMSO group was supplemented with 0.05% DMSO, and FNB1, FNB2 and FNB3 groups were supplemented with 12.5, 25 and 50 μg/mL FNB, respectively.After cultured in vitro for 4, 8, 12 and 24 h, supernatants and cells were collected from each group separately, and then the content of nitric oxide (NO) in the supernatants, intracellular activity of reactive oxygen species (ROS), inducible nitric oxide synthase (iNOS), xanthine oxidase (XOD), myeloperoxidase (MPO) and intracellular content of malonaldehyde (MDA) at each time were determined by kits.【Result】 The results showed that the TCID₅₀ of PRV was 10^-8.25/0.1 mL.Compared with BC group, the level of NO in the supernatant of PRV group was extremely significantly decreased at 4 and 8 h and extremely significantly increased at 12 and 24 h (P<0.01), the content of intracellular ROS was significantly reduced at 4 h (P<0.05), and significantly or extremely significantly increased at 8-24 h (P<0.05 or P<0.01).The activities of iNOS and XOD were significantly or extremely significantly increased at 8-24 h (P<0.05 or P<0.01).The activity of MPO was significantly increased at 4-24 h (P<0.05).The content of MDA was significantly decreased at 4 h and significantly increased at 12-24 h (P<0.05).Compared with PRV group, the content of NO in FNB2 group was increased significantly or extremely significantly at 4-8 h (P<0.05 or P<0.01), and significantly reduced at 12 h (P<0.05), and was extremely significantly increased at 24 h in FNB3 group (P<0.01).The level of intracellular ROS was extremely significantly increased at 4 h (P<0.01), and extremely significantly decreased at 8-24 h (P<0.01).The activity of iNOS in FNB1 group was significantly increased at 4 h (P<0.05), and were significantly or extremely significantly increased at 8-24 h in the three FNB groups (P<0.05 or P<0.01).The activities of MPO and XOD were significantly or extremely significantly reduced at 4-24 h (P<0.05 or P<0.01).The content of MDA was significantly increased at 4 h and significantly increased at 8 h in FNB2 and FNB3 groups (P<0.05).The content of MDA were significantly reduced at 24 h in FNB1 and FNB2 groups (P<0.05).【Conclusion】 FNB could regulate the level of oxidative stress by interfering the secretion level of oxidative stress-related factors, and maintain the balance between oxidation and antioxidant.The results might provide a theoretical basis for the development and application of FNB.

Key words: N-butanol fraction of Polygonum hydropiper flavonoids (FNB); Pseudoabies virus (PRV); 3D4/2 cells; oxidative stress