Optimisation and biological evaluation of palm glyceryl monocaprylate antimicrobial nanoemulsion for combating S. aureus wound infection

Fatty acids derived from renewable sources have been shown to have promising antibacterial activity. Palm glyceryl monocaprylate (GMCY), a medium chain fatty acids derived from palm kernel oil, was reported to have bactericidal effects. In this study, the potential application GMCY as antibacterial nanoformulation for the treatment of infected wounds was explored. First, the antibacterial activity of GMCY was tested against three common wound bacteria. Then, GMCY nanoemulsion was designed and optimised using response surface methodology (RSM) with particle size, zeta potential and polydispersity index as the response variables. In vivo infected wound healing study was conducted to examine the healing efficacy of the optimized GMCY nanoemulsion. It was showed that GMCY exhibited bactericidal properties against S. aureus and E. coli. At the nanoemulsion developmental stage, statistical analyses have demonstrated there was a direct correlation between GMCY concentration and the particle size and polydispersity index. Through the RSM models developed, an optimized nanoemulsion formulation that has the characteristics of 120 nm in particle size, -16.67 mV in zeta potential value and 0.1 polydispersity index. Electron microscopy observation on the bacteria morphology also demonstrated that increment in GMCY concentration as a direct effect on the disruption of the cell membrane integrity. From the animal study, it was found that the infected wounds in rats group treated with GMCY nanoemulsion was the most similar to normal healthy skin with no significant different. In conclusion, palm GMCY nanoemulsion can be explored as a plausible alternative antimicrobial formulation for the treatment of infected wounds. (C) 2020 The Authors. Published by Elsevier B.V.