In addition, the levels of antioxidant enzymes and phase 2 detoxifying enzymes, such as NADP(H): quinone oxidoreductase (NQO1) and the stress response protein heme oxygenase (HO-1), were increased in COPD mice and were found to be downregulated by BFHX. This evidence concerns the gene HMOX1 and chronic obstructive pulmonary disease.