Systematic modification of the presumed P1 side chain in a series of (carboxyalky1) amino- based inhibitors of matrix metalloproteinases enabled identification of the 24 1, 3-dihydro-1, 3-dioxo-2H-benz [flisoindol-2-yl) ethyl group as a preferred substituent imparting potent inhibition of the enzymes collagenase and gelatinase. It was subsequently found that the P2'- P3'residues in this series could be replaced by small non-peptide residues, while ...