Effects of erdosteine and its metabolites on bacterial adhesiveness

Erdosteine (CAS 84611-23-4) is administered as a mucolytic drug in patients with pulmonary disorders who suffer from a thickening of bronchial mucus with altered physico-chemical characteristics. Erdosteine itself does not have a free thiol group but its metabolization produces active metabolites with a -SH group that is capable of breaking disulfide bonds of mucins and improving the mucociliary clearance of the airways, and thus reproducing the effects of the class of muco-active drugs having a thiol group. It has also been reported that muco-active drugs with this group reduce bacterial adhesiveness to human mucosal cells. The aim of this study was to investigate whether erdosteine and its SH-metabolites are capable of interfering with bacterial adhesiveness. Metabolite I significantly reduces both S. aureus and E. coli adhesiveness to human mucosal epithelial cells at concentrations of 2.5, 5 and 10 micrograms/ml. The same concentrations of erdosteine, metabolite II, metabolite III and N-acetylcysteine (as a control drug) were devoid of such activity, whereas the results of hemagglutination and hydrophobicity assays showed that the behaviour of metabolite I overlapped that of bacterial adhesiveness, thus indicating that interference takes place at a fimbrial level. This is confirmed by the fact that the incubation of human buccal cells with drugs does not reduce the adhesiveness of untreated bacteria. The presence of this additional activity in a muco-active drug is useful because bacteria not only adhere to epithelial cells but also to tracheobronchial secretions.