 catechin.Two molecular features of most MMP inhibitors are responsible for the affinity.One is a chelating moiety that interacts with the zinc ion and the other is a hydrophobic extension from the catalytic site that project into S1’ pocket (P1’ group) of the metalloproteinase.The structural difference MMPs’ is mainly in the S1’ side and by modifying the P1’ group, inhibitor selectivity can be developed.