The sulfamide motif in the design of enzyme inhibitors

The sulfamide moiety, similarly to the structurally related sulfonamide and sulfamate ones, is widely employed in medicinal chemistry for the design of biologically active compounds. Amongst the enzymes for which sulfamide-based inhibitors were designed are the carbonic anhydrases (CAs), and a large number of proteases belonging to the aspartic protease (HIV-1 protease, gamma-secretase), serine protease (elastase, chymase, tryptase and thrombin, among others) and metalloproteinase (carboxypeptidase A [CPA] and matrix metalloproteinase [MMP]) families. Some steroid sulfatase (STS) and protein tyrosine phosphatase inhibitors belonging to the sulfamide class of derivatives have also been reported. In all these compounds, many of which show low nanomolar affinity for the target enzymes for which they have been designed, the free or substituted sulfamide moiety plays an important role in the binding of the inhibitor to the active site cavity. This is achieved either by directly coordinating to the metal ion found in some metalloenzymes (CAs, CPA, STS), usually by means of one of the nitrogen atoms present in the sulfamide motif, or, as in the case of the cyclic sulfamides, acting as HIV protease inhibitors interacting with the catalytically critical aspartic acid residues of the active site by means of an oxygen atom belonging to the HN-SO2-NH motif that substitutes a catalytically essential water molecule. In other cases, the sulfamide moiety is important for inducing desired physicochemical properties to the drug-like compounds incorporating it, such as enhanced water solubility, better bioavailability etc., due to the intrinsic properties of this highly polarised moiety when attached to an organic scaffold. This interesting motif is, thus, of great value for the design of pharmacological agents with many applications.