BACKGROUND AND OBJECTIVE: Pulmonary fibrosis is a chronic interstitial lung disease caused by parenchymal lung damage due to inflammatory factors and fibrosis. Hypericum perforatum contains various flavonoids with antioxidant properties. This study aimed to evaluate protective effects of hydroalcoholic extract of Hypericum against bleomycin-induced pulmonary fibrosis in rats. 

METHODS: This empirical study was conducted on 30 Wistar rats weighing 150-180 grams. Animals were randomly divided into five groups of six. Group one received a single dose of normal saline intraperitoneally, and group two was administered with bleomycin (7.5 units per kg) intratracheally. Other groups received daily doses of Hypericum extract (50, 100 and 200 mg/kg) via intraperitoneal injection one week before and two weeks after bleomycin administration. After 21 days, animals were sacrificed, and blood and lungs were collected for histopathological examinations, and measurement of plasma malondialdehyde (MDA) and lung hydroxyproline (HP).    

FINDINGS: In this study, lung index, HP and plasma MDA in normal saline group were respectively 7.09±0.32 mg per kilogram of body weight, 1.80±0.23 mg per gram of lung tissue, and 1.32±0.27 micromoles per liter of plasma. In rats administered with bleomycin, these values were 9.75±0.90, 5.43±0.7 and 3.04±0.42, respectively. Treatment with Hypericum extract, especially at dosage of 200 mg/kg, resulted in a significant reduction in the aforementioned parameters compared to bleomycin group (p<0.05).  

CONCLUSION: According to the results of this study, hydroalcoholic extract of Hypericum perforatum could exert protective effects against bleomycin-induced pulmonary fibrosis