Evaluation of the Antimicrobial and Antivirulent Potential of Essential Oils Isolated from Juniperus oxycedrus L. ssp. macrocarpa Aerial Parts

Abstract

As a consequence of the worsening situation with multidrug-resistant (MDR) pathogens and a disparity in the commercialization of novel antimicrobial agents, scientists have been prompted to seek out new compounds with antimicrobial activity from a wide range of sources, including medicinal plants. In the present study, the antibacterial, antifungal, anti-virulence, and resistance-modulating properties of the essential oil from the Sardinian endemic <i>Juniperus oxycedrus</i> L. ssp. <i>macrocarpa</i> aerial parts were evaluated. The GC/MS analysis showed that the main compounds in the oil were α-pinene (56.63 ± 0.24%), limonene (14.66 ± 0.11%), and β-pinene (13.42 ± 0.09%). The essential oil showed potent antibacterial activity against Gram-positive bacteria (0.25-2 <i>v/v</i>%) and <i>Salmonella</i> spp. (4 <i>v/v</i>%). The strongest fungicidal activity was recorded against <i>Candida auris</i> sessile cells (median FICI was 0.088) but not against <i>C. albicans</i> biofilms (median FICI was 1). The oil showed potent efflux pump inhibitory properties in the case of <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>. The therapeutic potential of Juniperus may be promising for future more extensive research and in vivo tests to develop new drugs against antibiotic and antifungal resistance.