Magnesium nanohydroxide (2D brucite) as a host matrix for thymol and carvacrol: Synthesis, characterization, and inhibition of foodborne pathogens

Abstract

Terpenes, such as thymol and carvacrol, are phenols that exhibit antioxidant and antimicrobial activities but are unstable in the presence of light or oxygen. Layered hydroxide salts are laminar compounds that can host molecules in their interlaminar space, protecting them from degradation and delivering bioactive molecules in a sustained manner. In the present study, hybrids composed of brucite, thymol, or carvacrol were synthesized by precipitation and anion-exchange process. The structure was confirmed by X-ray diffraction, and characteristic hexagonal morphology was verified by scanning electronic microscopy. The antibacterial activity of hybrids was evaluated against foodborne pathogens (Escherichia coli, Salmonella Enteritidis, Listeria monocytogenes, and Staphylococcus aureus), obtaining an inhibition of 80% for both Gram-positive and -negative bacteria, while inhibition of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) was 65% for carvacrol and 93% for thymol. Finally, the exposition of hybrids to Artemia salina proved to be non-toxic up to 200 mg·mL−1. The results suggest that these hybrids can control pathogen growth and exhibit antioxidant activity without threatening consumers’ health in the case of consumption, which helps develop novel and safe products applied in the food industry.

Keywords

• layered compounds
• terpenes
• antimicrobial activity
• antioxidant activity
• toxicity