Aged red garlic extract reduces lipopolysaccharide‐induced nitric oxide production in <scp>RAW</scp> 264.7 macrophages and acute pulmonary inflammation through haeme oxygenase‐1 induction

Abstract Aim It is known that garlic has antioxidative and anti‐inflammatory properties. Aged red garlic ( ARG ), a novel aged garlic formulation, has higher antioxidant effects than fresh raw garlic. This study was performed to examine the anti‐inflammatory effects of ARG extract ( ARGE ). Methods The anti‐inflammatory effects of ARGE were evaluated in the lipopolysaccharide ( LPS )‐treated R aw 264.7 macrophages and acute lung inflammatory mice. NO production was determined by the G riess method, and iNOS , HO ‐1 and COX ‐2 expressions were measured using W estern blot analysis. Histology and inflammation extent of lung were analysed using haematoxylin–eosin staining and immunohistochemistry. Results ARGE treatment markedly reduced LPS ‐induced nitrite production in RAW 264.7 macrophages and reduced inducible nitric oxide synthase ( iNOS ) expression. Treatment of cells with ARGE led to a significant increase in haeme oxygenase‐1 ( HO ‐1) protein expression, which was mediated by stimulating the expression of nuclear factor erythroid 2‐related factor 2 ( N rf2). Treatment with zinc protoporphyrin, a selective inhibitor of HO ‐1, significantly reversed the ARGE ‐mediated inhibition of nitrite production ( P &lt; 0.05). In LPS ‐induced inflammatory mice, ARGE treatment down‐regulated iNOS and COX ‐2 expressions, while it up‐regulated HO ‐1 expression. Conclusion These results show that ARGE reduces LPS ‐induced nitric oxide production in RAW 264.7 macrophages through HO ‐1 induction and suggest that ARGE may have potential effects on prevention and treatment of acute inflammatory lung injury.