Composition and biological activity of supercritical CO2 extract of some Lamiaceae growing wild in Sardinia (Italy)

Three aromatic plants (lavender, thyme, and rosemary) typical of the Mediterranean area, were collected in Sardinia (Italy island) and supercritical carbon dioxide extracts were prepared. The extracts were analyzed using GC and GC-MS and tested for their potential antibacterial and antifungal activities. α-Pinene (34.5 %), bornyl acetate (19.1 %) and verbenone (18.5 %) were the most representative components of Rosmarinus officinalis L. extract. Lavandula stoechas ssp. stoechas extract exhibited three high percent components: camphor (31.7 %), fenchone (20.7 %) and 1,8-cineole (10.9 %). The extract of Thymus capitatus (L.) Hoffmanns. & Link was found to be predominantly composed by carvacrol (87.8 %), followed by β-caryophyllene (2.3 %) and p-cymene (2.2 %). The antimicrobial activity was tested against two bacterial species (Staphylococcus aureus and Escherichia coli) and two fungi (Candida albicans and Candida glabrata). Minimal Inhibitory Concentration (MIC) and Minimal Cidal Concentration (MCC) values were determined using the broth dilution method. Rosemary and lavander supercritical extracts failed to inhibit any organism at the highest concentration (2.5 %). The extracts of T. capitatus exhibited a bacteriostatic effect against yeast clinical strains and an activity against E. coli (MIC = 0.6 %) and S. aureus (MIC = 0.078 %)