Abstract: Fifty-four Wistar rats were randomly divided into six groups: control group, model group, white silver needle extract group, high and low dose white peony extracts and EGCG group, with 9 rats in each group. The other five groups except the control group were treated with nano-sized SiO₂ dust (80 mg·mL^-1) by non-exposed endotracheal intubation. After two weeks of intragastric administration, the contents of hydroxyproline(HYP), nitric oxide (NO), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px) and the morphological changes of lung tissues were detected. The results show that compared with the model group, the pathological changes of each white tea extract treatment group and EGCG group were alleviated in varying degrees, and the effect of white silver needle extract group was the best. The content of NO and inflammatory factor IL-6 in lung of rats treated with white tea extract and EGCG were significantly lower than those of model group (P<0.05), GSH-Px activity was higher than that of model group (P<0.05). High-dose white peony extract group had the best effect on reducing NO content and increasing GSH-Px activity. This study shows that white tea extract had a significant effect on oxidative stress injury of lung fibrosis induced by nano-sized SiO₂ in rats. The slow and repairing effects are mainly related to the antioxidant effect and the inhibition of inflammatory reaction.

Key words: white tea extract, nano-sized SiO₂, wistar albino rat, pulmonary fibrosis, inhibition, recovery