Mucoadhesive S-protected thiolated cyclodextrin-iodine complexes: a promising strategy to prolong mucosal residence time of iodine.

AIM

The purpose of this study was to develop S-protected thiolated α-cyclodextrin-iodine complexes providing prolonged mucosal residence time and sustained release of the antimicrobial agent.

MATERIALS & METHODS: First, L-cysteine was conjugated with 2-mercaptonicotinic acid to generate cysteine-2-mercaptonicotinic acid (Cys-MNA). Subsequently, α-CD was oxidized with NaIO and Cys-MNA was bound to the resulting aldehyde groups via reductive amination. Finally, iodine was incorporated into complex.

RESULT

S-protected thiolated α-CD displayed 3804 μmol/g MNA groups. The inclusion constant (K) between iodine and S-protected thiolated α-CD was 5.37 × 10 M. In vitro release of iodine was around 15% per hour, whereas mucoadhesive properties showed 38-fold improvement in mucoadhesion. The complex did not show cytotoxicity at a concentration of 0.5% (m/v). In addition, complexes exhibited pronounced antimicrobial activity against Staphylococcus aureus and Escherichia coli.

CONCLUSION

According to these results, S-protected thiolated α-CD-iodine complex might be a promising novel formulation for the mucosal use of iodine.