Apigenin protects against bleomycin-induced lung fibrosis in rats

Apigenin is a non-toxic and non-mutagenic flavone that exists abundantly in numerous herbs and vegetables. Apigenin exerts anti-proliferative and anti-inflammatory properties. The aim of the present study was to investigate the effects of apigenin on bleomycin-induced lung fibrosis in rats. A single intratracheal instillation of bleomycin (5 mg/kg) was administered and rats were sacrificed on 7 and 28 days post bleomycin instillation. The instillation of bleomycin resulted in decreased body weight and an increase in the lung index. In addition, bleomycin administration increased the hydroxyproline content, myeloperoxidase (MPO) activity, tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β levels and decreased the superoxide dismutase (SOD) activity in the rat lung tissues. Excessive collagen deposits were detected in the lung tissues in bleomycin-treated rats compared with normal control rats. Notably, the oral administration of apigenin (10, 15 and 20 mg/kg/day) appeared to prevent the fibrotic process. The treatment suppressed the increases in hydroxyproline content, MPO activity, TNF-α and TGF-β levels and attenuated the reduction of SOD activity that were induced by bleomycin. Furthermore, excessive collagen deposition was inhibited by the apigenin treatment. Collectively, these results suggest that apigenin may function as a potent anti-inflammatory and anti-fibrotic agent against bleomycin-induced lung fibrosis.