The present invention provides a plant derived extract comprising inhibitory activity against one or more extracellular proteases which degrade human tissue matrix. Moreover, the amount of inhibitory activity in an extract can be increased by stressing the plant prior to forming an extract. These extracts are each prepared by a standard process and demonstrate the ability to inhibit one or more extracellular proteases which degrade human tissue matrix. Libraries of extracts can be prepared from stressed and non-stressed plants, wherein each of the extracts demonstrate inhibitory activity against one or more extracellular protease inhibitors. Alternatively, semi-purified and purified inhibitory compounds can be isolated from the extracts following standard procedures. In one aspect, these extracts with inhibitory activity can be used during protein purification to minimize the degradation due to extracellular proteases.