The genus Thymus L., belonging to the Lamiaceae family, contains about 220 species with a distribution that mainly extends in Europe, northwest Africa, Ethiopia, Asia, and southern Greenland. Due to their excellent biological properties, fresh and/or dried leaves and aerial parts of several Thymus ssp. have been utilized in the traditional medicine of many countries. To evaluate not only the chemical aspects but also the biological properties, the essential oils (EOs), obtained from the pre-flowering and flowering aerial parts of Thymus richardii subsp. nitidus (Guss.) Jalas, endemic to Marettimo Island (Sicily, Italy), were investigated. The chemical composition of the EOs, obtained by classical hydrodistillation and GC-MS and GC-FID analyses, showed the occurrence of similar amounts of monoterpene hydrocarbons, oxygenated monoterpenes, and sesquiterpene hydrocarbons. The main constituents of the pre-flowering oil were β-bisabolene (28.54%), p-cymene (24.45%), and thymol methyl ether (15.90%). The EO obtained from the flowering aerial parts showed as principal metabolites β-bisabolene (17.91%), thymol (16.26%), and limonene (15.59%). The EO of the flowering aerial parts, and its main pure constituents, β-bisabolene, thymol, limonene, p-cymene, and thymol methyl ether were investigated for their antimicrobial activity against oral pathogens and for their antibiofilm and antioxidant properties.

The genus Lavandula L., belonging to the Lamiaceae family, contains about forty species with a distribution that mainly extends in the Mediterranean basin from the North Atlantic to the Middle East. Due to their excellent biological properties, the aerial parts and flowers of Lavandula peduncolata ssp. have been utilized in traditional medicine in Morocco and western Europe. This paper investigated the chemical composition and antibacterial activities as well as the antibiofilm and antioxidant activities of the essential oil (EO) obtained from the pre-flowering aerial parts of Lavandula pedunculata subsp. atlantica collected in Morocco. The chemical composition of the EO, obtained by classic hydrodistillation, showed by GC-MS analysis the presence of a large amount of oxygenated monoterpene compounds. The main constituents of the EO were camphor (27.8%), camphene (10.9%), fenchone (10.6%), and eucalyptol (8.5%). The EO has been evaluated for its antimicrobial, antibiofilm, antioxidant and anti-inflammatory properties, showing promising activity against both Gram-positive and Gram-negative strains. These findings highlight the potential of Lavandula EO in combating infections caused by Streptococcus mutans and Streptococcus oralis (oral diseases), Staphylococcus aureus (skin infections), Escherichia coli and Shigella sonnei (gastrointestinal and urinary infections). In addition, although the EO showed no evident effects on cell viability in eukaryotic epithelial cells, it exhibited promising effects on anti-inflammatory properties.

Silver drugs have played a vital role in human healthcare for the treatment of infections for many centuries. Currently, due to antibiotic resistance, a potential scenario or the application of silver complexes may arise as substitutes for conventional antibiotics. In this perspective, N-heterocyclic carbene (NHC) ligands have been selected as carrier molecules for silver ions. In this study, we selected two mono NHC-silver halide complexes: bromo[1,3-diethyl-4,5-bis(4-methoxyphenyl)imidazol-2-ylidene]silver(I) (Ag4MC) and chloro[2-pyridin- N-(2-ethylacetylamido)-2-yl-2H-imidazol-2-ylidene]silver(I) (Ag5MC), and two cationic bis NHC silver complexes: bis[1,3-diethyl-4,5-bis(4-methoxyphenyl)imidazol-2-ylidene]silver(I) (Ag4BC) and bis[2-pyridin-N-(2-ethylacetylamido)-2-yl-2H-imidazol-2-ylidene]silver(I) (Ag5BC). The inhibitory properties of the four complexes were evaluated for their antimicrobial potential against a set of Gram (+) and Gram (−) bacterial strains and the fungus C. albicans. In addition, further investigations were made using fluorescence and scanning electron microscopy (SEM) in order to gain more insights into the mechanism of action. Some preliminary information on the Ag target was obtained by analyzing the cytosol of E. coli treated with Ag5MC by size-exclusion chromatography (SEC) coupled with inductively coupled plasma mass spectrometry (ICP-MS).

Given the continuous increase in antibiotic resistance, research has been driven towards the isolation of new antimicrobial molecules. Short, charged, and very hydrophobic antimicrobial peptides have a direct action against biological membranes, which are less prone to developing resistance. Using a bioinformatic tool, we chose the SQQ30 peptide, isolated from the human SOGA1 protein. The antimicrobial activity of this peptide against various Gram-negative and Gram-positive bacterial strains and against a fungal strain was studied. A mechanism of action directed against biological membranes was outlined. When administered in combination with the antibiotic ciprofloxacin and with the TRS21 (buforin II), another antimicrobial peptide, SQQ30 can be used with a lower MIC, showing additivity and synergism, respectively. Particularly interesting is the ability of SQQ30 to bind LPS in Gram-negative strains, preventing the eukaryotic cell from releasing inflammatory mediators. Our study indicates SQQ30 as a novel and promising antimicrobial agent.

Pastinaca L. is a small genus belonging to the Apiaceae family, traditionally used for both nutritional and medicinal purposes. Pastinaca sativa L. subsp. sativa is a biennial plant widely distributed in Europe and Asia, with recognized ethnopharmacological relevance. In this study, the essential oil (EO) obtained from the aerial parts of P. sativa subsp. sativa, collected in Alto Adige (Italy)—a previously unstudied accession—was analyzed by GC-MS, and the volatile profile has been compared with that of EOs previously studied in Bulgaria and Serbia. The EO was found to be rich in octyl acetate (38.7%) and octyl butanoate (26.7%), confirming that this species biosynthesizes these natural esters. The EO and its main constituents were tested to evaluate their antimicrobial properties. Furthermore, their biological potential was evaluated through antimicrobial, antibiofilm and antioxidant assays. This research work, in addition to evaluating possible chemotaxonomic differences at the geographical level of EOs of Pastinaca sativa subsp. sativa, has been extended to the determination of the biological properties of this accession never investigated before, with the aim of acquiring a broader vision of biofilm and antibacterial properties.

Athamanta L. is a small genus of the Apiaceae family, comprising only sixteen species and subspecies, which are distributed in the Canary Islands, Central Europe, and the Mediterranean basin. Background/Objectives: Since the time of Dioscurides, the species of this genus have been reported to have had several ethnopharmacological activities, and some of them are also used currently. Athamanta sicula L., growing in Italy, Tunisia, Algeria, and Morocco, is the only species of this genus present in Sicily. To further explore the phytochemical profile and biological properties of this species, the present study focused on the essential oil (EO) extracted from the aerial parts of wild A. sicula populations collected in central Sicily. Methods: The chemical composition of the EO, obtained by hydrodistillation, was determined by GC–MS analysis. The presence of myristicin was confirmed by isolation and by ¹H-NMR spectroscopic characterization. Results: The EO and its main constituents have been tested for possible antimicrobial properties against several bacterial strains, showing MIC values in the of 15–30 mg/mL range, and the mechanism of action was further investigated, revealing membrane-targeting effects consistent with outer membrane permeabilization. In addition, antibiofilm activity (with up to ~80% inhibition of biofilm formation at sub-MICs), antioxidant potential (demonstrating dose-dependent radical scavenging activity), and biocompatibility with eukaryotic cells were assessed to provide a comprehensive pharmacological profile of A. sicula EO. Specifically, the most abundant constituent was myristicin (62.2%), the principal representative of the phenylpropanoid class (64.4%). Hydrocarbon monoterpenes represented the second class of the EO (27.4%), with β-phellandrene (12.2%) as the main compound. Conclusions: Myristicin emerged as the key contributor to the antimicrobial and antibiofilm activity of the EO. The obtained results highlight the relevance of A. sicula EO as a myristicin-rich essential oil with notable in vitro biological activity.