The present invention relates to an active agent, in particular a metalloproteinase inhibitory agent of casein-derived peptides obtained by hydrolysis of casein by a food grade bacteria. The invention also relates to the manufacture of an active agent, in which a food grade bacteria of the genus Lactobacillus helveticus is contacted with casein in order to perform a hydrolysis and obtain casein-derived peptides exhibiting metalloproteinases inhibitory property. The present invention also includes isolated and purified inhibitory peptides obtained by hydrolysis of casein by the bacteria.