Benzoic acid complexes with Eudragit E100®: New alternative antimicrobial preservatives

Area of Science:

• Cosmetic Science
• Materials Science
• Microbiology

Background:

• Regulatory restrictions on traditional cosmetic preservatives necessitate the development of novel alternatives.
• Benzoic acid (BA) and Eudragit E100 are key components for creating new preservative systems.
• Polyelectrolyte complexes offer a potential avenue for enhanced preservative efficacy.

Purpose of the Study:

• To characterize the physicochemical and antimicrobial properties of two polyelectrolyte complexes, EuB100 and EuB75Cl25.
• To evaluate the potential of these complexes as alternative antimicrobial preservatives in cosmetic formulations.
• To investigate the interaction between benzoic acid and Eudragit E100 within the complexes.

Main Methods:

• Hot melt extrusion (HME) was employed to develop the polyelectrolyte complexes.
• Physicochemical characterization included phase diagrams, FTIR, XPS, and XRPD.
• Antimicrobial activity and zeta potential were assessed against Escherichia coli.

Main Results:

• Fourier-transform infrared spectroscopy (FTIR) indicated acid-base interactions between benzoic acid and Eudragit E100.
• X-ray photoelectron spectroscopy (XPS) confirmed protonation of nitrogen atoms in the polymer.
• The developed complexes demonstrated satisfactory antibacterial activity against E. coli at pH 6.9, with modified zeta potential affecting bacterial membrane function.

Conclusions:

• The polyelectrolyte complexes EuB100 and EuB75Cl25 exhibit significant potential as antimicrobial preservatives.
• These complexes offer a broader spectrum of action and bactericidal activity against E. coli at a wider pH range compared to uncomplexed benzoic acid.
• The findings support the use of these novel complexes as effective alternatives in cosmetic preservation.