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A new lipid emulsion formulation with high antimicrobial efficacy using chitosan
Muhannad Jumaa1, Franz H Furkert, Bernd W Müller
1Pharmaceutical Chemistry Department, University of Kansas, Lawrence, KS, USA.
Summary
Chitosan demonstrates antimicrobial properties in lipid emulsions and aqueous solutions, with optimal activity at specific pH levels. A low-viscosity chitosan type proved more effective, meeting preservation standards for topical formulations.
Area of Science:
- Biochemistry
- Microbiology
- Materials Science
Background:
- Chitosan, a biopolymer derived from chitin, possesses inherent antimicrobial properties.
- Understanding chitosan's efficacy in different formulations is crucial for its application as a preservative.
- Variations in chitosan molecular weight and deacetylation degree influence its biological activity.
Purpose of the Study:
- To investigate the antimicrobial activity of chitosan in both aqueous solutions and lipid emulsions.
- To determine the optimal pH for chitosan's antimicrobial action against specific microorganisms.
- To evaluate the preservative efficacy of chitosan in emulsion formulations according to European Pharmacopoeia standards.
Main Methods:
- Two chitosan types with distinct molecular weights and deacetylation degrees were used.
- Microbial suspensions (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, Aspergillus niger) were incubated with chitosan at varying pH levels.
- Emulsion formulations with and without chitosan were inoculated and incubated.
- Microbial counts were assessed using agar plate methods.
- Hemolysis studies were performed on human erythrocytes.
Main Results:
- Chitosan exhibited antimicrobial activity in aqueous solutions, reducing bacterial counts.
- Optimal antibacterial activity was observed at pH 5.0-5.1 for P. aeruginosa and pH 5.3 for S. aureus.
- Chitosan with higher deacetylation and lower viscosity showed superior antimicrobial efficacy.
- Lipid emulsions with 0.5% chitosan met European Pharmacopoeia preservation efficacy test requirements.
- Emulsions with chitosan displayed negligible hemolytic activity.
Conclusions:
- Chitosan is effective as an antimicrobial agent in lipid emulsions and aqueous solutions.
- Specific pH conditions enhance chitosan's antibacterial activity.
- Chitosan type significantly impacts its antimicrobial potency.
- Chitosan-containing lipid emulsions are suitable preservatives for topical, mucosal, and parenteral applications.