Effect of flavones on rat brain and lung matrix metalloproteinase activity measured by film in-situ zymography

We have evaluated the inhibitory activity of flavone, nobiletin, and heptamethoxyflavone on matrix metalloproteinase (MMP) activity in the rat. MMP in 9000‐g supernatant fraction of lung homogenate was activated by p‐aminophenyl mercuric acetate (APMA), and gelatinolytic activity was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) followed by Coomassie staining. This activity should be related to MMP‐2 and/or MMP‐9 and was confirmed by gelatin zymography. Fluorescent‐conjugated collagen used as a substrate for collagenolytic activity was investigated by SDS‐PAGE also. The film in‐situ zymography method was applied to rat brain and lung tissue in the same manner. Flavone and nobiletin inhibited the APMA‐stimulated gelatinolytic activity and also the collagenolytic activity by more than 75%. The film in‐situ zymography method indicated that these compounds might be potent inhibitors of MMP, suggesting the specific inhibition of localized MMP in brain hippocampus and/or lung terminal bronchioles, which may contribute to the prevention of some types of brain disease or cancer invasion and metastasis.