The central role of collagen as the major structural fibrous protein in the mammalian extracellular matrix has motivated a significant effort toward the determination of its mechanical properties at all levels, ranging from single monomers and long-chain polymers to a structural element within a biological tissue. However, the stabilization of collagen against collagenolytic degradation finds significance in biomedical and industrial applications. Tannins are plant-derived polyphenols that have the ability to inhibit the collagenase activity at minimum concentration. The inhibitory effect of wattle (Acacia mollissima) and myrobalan (Terminalia chebula) on the action of collagenase against collagen was probed in this study. The kinetics of the inhibition of collagenase by wattle and myrobalan was deduced from the extent of hydrolysis of 2-furanacryloyl-L-leucyl-glycyl-L-prolyl-L-alanine. Both wattle and myrobalan tannin exhibited competitive modes of inhibition against collagenase. Circular dichroism studies of collagenase on treatment with wattle and myrobalan revealed changes in the secondary structure of collagenase. These results suggest that the tannins of A. mollissima and T. chebula extracts facilitated collagen stabilization through collagenase inhibition. (c) 2007 Wiley Periodicals, Inc.