Antimicrobial potential of natural deep eutectic solvents

Natural deep eutectic solvents (NADES) are a new class of green solvents, which can solubilize natural and synthetic chemicals of low water solubility. NADES are mixtures of two or three compounds of hydrogen bond acceptors and hydrogen bond donors. Many NADES’ components are of natural origin and therefore, NADES are presumed to be nontoxic and often exhibit antimicrobial activity. This work aimed to investigate the potential antimicrobial effect of menthol, capric acid and Solutol™, and their associated eutectic system on two Gram‐positive bacteria (Staphylococcus aureus ATCC 6538 and Bacillus subtilis ATCC 6633), two Gram‐negative bacteria (Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027) and one fungus (the yeast Candida albicans ATCC 10231). The results obtained showed a stronger antimicrobial effect for the NADES when compared to their individual components and that they exhibit a promising antimicrobial activity against S. aureus and C. albicans and good activity against P. aeruginosa. NADES exhibited no observable antimicrobial activity against spore‐forming B. subtilis. Significance and Impact of the Study: Natural deep eutectic solvents (NADES) are a new class of green solvents, which can solubilize natural and synthetic chemicals of low water solubility. In this study, a novel eutectic system was prepared from a ternary mixture of capric acid, menthol and Solutol™. Upon contact with water, such ternary eutectic mixtures form what are known as eutectic self‐nanoemulsified systems. The individual components and their binary and ternary mixtures were tested for their antimicrobial potential against a panel of bacteria (i.e., Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) and a yeast (i.e., Candida albicans).