Mucoadhesive S-Protected Thiolated Cyclodextrin-Iodine Complexes: A Promising Strategy to Prolong Mucosal Residence time of Iodine

Abstract

Aim: The purpose of this study was to develop S-protected thiolatedα-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 NaIO₄ 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 3804μmol/g MNA groups. The inclusion constant (K_C) between iodine and S-protected thiolated α-CD was 5.37×10⁴ M^-1. 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.

Keywords: :

• α-cyclodextrin
• antimicrobial activity
• cyclodextrin
• drug delivery
• iodine
• iodine release
• mucoadhesion
• S-protected thiolated cyclodextrin
• thiolated cyclodextrin
• thiomers

Supplementary data

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Financial and competing interests disclosure

This research work was supported by the Higher Education Commission (HEC), Pakistan and the Austrian Agency for International Cooperation in Education and Research (OeAD), Austria. We are also thankful to Department of Microbiology, Khyber Medical University, Peshawar-Pakistan, for testing antimicrobial activity. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

This research work was supported by the Higher Education Commission (HEC), Pakistan and the Austrian Agency for International Cooperation in Education and Research (OeAD), Austria. We are also thankful to Department of Microbiology, Khyber Medical University, Peshawar-Pakistan, for testing antimicrobial activity. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed