Two samples of the essential oils from Thymus herba-barona Loisel (Labiatae) of Sardinian origin were chemically characterized and their antimicrobial activity evaluated, in comparison with T. vulgaris and T. serpyllum oils, on the basis of their minimum inhibitory concentrations (M.I.C.s) and of the contact times required to totally inhibit development of microorganisms. GC and GC/MS analysis showed that the main components of essential oils of T. herba-barona were carvacrol (75.4% and 73–0%), borneol (3.6% and 6.4%) and p-cymene (3.9% and 3.3%), while the percentage of thymol was very low (1.0% and 0.7%). Results of the antimicrobial investigation demonstrated that both oils possessed similar and relevant microbicidal activities, especially against Gram+ bacteria (M.I.C.s range 0.125–0.500 mg/mL) and mycetes (M.I.C.s 0.125–0.500 mg/mL). At inhibitory concentrations, times required to kill microbial inocula (5–10 min) are comparable with those of chlorhexidine gluconate, an antiseptic with a broad range of antimicrobial activities. The strong activity of T. herba-barona oils is very probably due to the presence of carvacrol, which was found from our screenings to exhibit a similar antimicrobial activity. Our findings provide for a rationale basis of a possible utilization of this oil in fields requiring safe and cheap compounds with antiseptic and preservative properties, such as cosmetic, pharmaceutical and food industries.

The fungitoxic activity against Penicillium digitatum, Penicillium italicum, Botrytis cinerea, and Alternaria citri of 12 essential oils (EOs) distilled from medicinal plants is reported. The resul...

The rapid emergence of drug-resistant strains and novel viruses have motivated the search for new anti-infectious agents. In this study, the chemical compositions and cytotoxicity, as well as the antibacterial, antifungal, antitrichomonas, and antiviral activities of essential oils from the leaves, rhizomes, and whole plant of Hornstedtia bella were investigated. The GC/MS analysis showed that β-pinene, E-β-caryophyllene, and α-humulene were found at high concentrations in the essential oils. The essential oils exhibited (i) inhibition against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis with minimum inhibitory concentrations (MIC) and minimum lethal concentration (MLC) values from 1 to 4% (v/v); (ii) MIC and MLC values from 2 to 16% (v/v) in Candida tropicalis and Candida parapsilosis; (iii) MIC and MLC values from 4 to 16% in Enterococcus faecalis; and (iv) MIC and MLC values from 8 to greater than or equal to 16% (v/v) in the remaining strains, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, and Candida glabrata. In antitrichomonas activity, the leaves and whole-plant oils of Hornstedtia bella possessed IC₅₀, IC₉₀, and MLC values of 0.008%, 0.016%, and 0.03% (v/v), respectively, whilst those of rhizomes oil had in turn, 0.004%, 0.008%, and 0.016% (v/v).Besides, the leaf oil showed a weak cytotoxicity against Vero 76 and MRC-5; meanwhile, rhizomes and whole-plant oils did not exert any toxic effects on cell monolayers. Finally, these oils were not active against EV-A71.

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 Juniperus oxycedrus L. ssp. macrocarpa 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 v/v%) and Salmonella spp. (4 v/v%). The strongest fungicidal activity was recorded against Candida auris sessile cells (median FICI was 0.088) but not against C. albicans biofilms (median FICI was 1). The oil showed potent efflux pump inhibitory properties in the case of Staphylococcus aureus and Escherichia coli. 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.