Minimum inhibitory but maximum non-hemolytic concentration of Larrea tridentata and Origanum vulgare extracts

Larrea tridentata and Origanum vulgare extracts are used in popular medicine to obtain antibacterial compounds to combat bacterial infections. Although the antibacterial activity of L. tridentata and O. vulgare extracts has been reported, hemolytic activity needs to be studied for therapeutic application. This work hypothesized minimum inhibitory but non-hemolytic concentration (MIC-NH) for L. tridentata and O. vulgare extracts. Thus, this study aimed to obtain non-hemolytic crude extracts with antibacterial activity. It was estimated that the MIC-NH of L. tridentata and O. vulgare extracts against the Staphylococcus aureus strain, an important skin pathogen bacterium, were 100 and 75 μg mL-1, respectively. Thus, these in vitro-tested extracts prevented the S. aureus strain growth without provoking hemolysis if the extract concentration was less or equal to the MIC-NH. At the same time, it was determined by gas chromatography coupled with mass spectroscopy that bis-ethylhexyl-phthalate, catechol, encecalinol, isopropyl cinnamate, phenol, guaiacine, and NDGA were antibacterial compounds in the L. tridentata extracts. Meanwhile, for O. vulgare extracts, these compounds were cymene, terpinene, thymol, carvacrol, cimendiol, hexadecanoic acid, bis-ethylhexyl-phthalate, and sitosterol. The findings of this research work must encourage the development of potential biomaterial coatings to replace conventional ones.