Formulation, antibacterial activity, and cytotoxicity of 1‐monoacylglycerol microemulsions

Abstract

Antibacterial activity of stable 1-monoacylglycerol (1-MAG) microemulsions (MEs) of capric (C10:0), undecanoic (C11:0), lauric (C12:0), and myristic (C14:0) acids against the growth of gram-positive and gram-negative bacteria was tested and their inhibition effect was compared to that of neat 1-MAG. To reveal their behavior with respect to eukaryotic cells, the cytotoxicity on mouse fibroblasts was also determined. The MEs were studied via pseudo-ternary phase diagrams in order to find out the miscibility areas of all components used. The results indicated that at 1-MAG concentrations of 1000-1900 mg/L, an inhibition of gram-negative strains was improved compared to neat 1-MAG and depended on the fatty acid type; however, at lower 1-MAG concentrations, both systems showed comparable effect. The opposite trend was detected on gram-positive bacteria, where 1-MAGs showed better performance compared to corresponding MEs. The best antibacterial activity against both bacterial types was observed in 1-MAG C12:0 MEs. MTT assay revealed significant cytotoxicity of all MEs. The threshold of 10 mg/L was determined as the limit for moderate toxicity, which represents 40-60% cell survival. All prepared MEs were transparent, stable during the storage period of 6 months and their particle sizes were between 15 and 20 nm.Practical applications: 1-MAGs belong to safe and efficient antimicrobial agents and their application may be a convenient alternative to usage of synthetic antimicrobials; however, one of their limitations for certain applications is their insolubility in aqueous systems. This drawback can be reduced by encapsulation of 1-MAGs in suitable ME system. The presented study has confirmed that 1-MAG MEs possess suitable inhibitory activity against both gram-negative and gram-positive bacteria. Efficacy of MEs against gramnegative strains was enhanced compared to 1-MAG alone. Although the growth of gram-positive bacteria was less affected by MEs when compared to neat 1-MAG, the results can be closely related to potential industrial applications of the MEs as effective agents for cosmetics, dermatology, food industry, paint or coatings where water-based systems are frequently used and desired. The application of studied systems might be to some extent limited due to the potential health risk caused by the observed cytotoxicity.

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Nanotechnology Formulations for Antibacterial Free Fatty Acids and Monoglycerides

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Essential oil micro- and nanoemulsions: promising roles in antimicrobial therapy targeting human pathogens

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“…, clove oil(Hamed et al 2012), sunflower oil(Joe et al 2012), black seed oil, 1-monoacylglycerol of lauric acid(Petra et al 2014), carvacrol, ethyl oleate(Al-Adham et al 2000, 2003, eucalyptus oil(Sugumar et al 2014), tea tree oil(Biju et al 2005;Lins et al 2016) and monolaurin(Fu et al 2009). …”