“…Beginning with the results of this study concerning the role of the nitrile group in the inhibition of the enzyme, and considering the activity showed by some vinyl sulfones, which will be described in the paragraph 6 of this review, as cysteine protease inhibitors [42,43], Kudryavtsev et al described the synthesis of novel 5-phenyl proline functionalizated with these two groups. Ultimately, however, they resulted weak inhibitors in the order of mM [44].…”