Pulmonary fibrosis is a fatal disease, and is considered as one of the most important side effects of chemotherapy drugs such as bleomycin. The antioxidant properties and anti-inflammatory activities of Hypericum have been confirmed; on the other hand, the inhibition of poly (ADP-ribose) polymerase enzyme affected the levels of nicotinamide adenine dinucleotide (NAD) in cells. In the present study, the effects of hypericum perforatum extract in combination with niacin were assessed on bleomycin-induced pulmonary fibrosis. In this study, male rats weighing 160-190 g were used. The animals were randomly divided into the following five groups of six: The control group (NS) , which receives normal saline only; the bleomycin group (BLM) , which was administrated with an endotracheal single dose of bleomycin sulfate solution after anesthetizing the animals. Hypericum perforatum (HP) group, Niacin group (100 mg/kg), and the combination group (HP + NC). In addition to receiving endotracheal bleomycin, the studied drug was administered intraperitoneally for 21 days. At the end of the study, hydroxy-proline and malondialdehyde were measured, and specific pathology tests were performed in lung tissues to determine the changes that occur in in various groups. The results showed that the lung index (lung weight/body weight), hydroxy-proline content (μg of hydroxyproline/lung), and malondialdehyde in the control group were 0.662±0.03 μg, 1156.8±41.5 μg ,and 753.7±40.2 μg respectively, while these values in the BLM group were 1.56± 0.24 μg, 4073.4±468.9 μg, and 1643.6 ± 129.9 μg, respectively. Treatment with the combination of hypericum extract and niacin significantly reduced these factors as compared to the bleomycin group (P < 0.05) .Our results represented a potential protection of hypericum extract and niacin on lung fibrosis induced by bleomycin. This protective effect showed a significant increase when compared to the use of the plant extract or niacin alone.
