This study is aimed at assessing the essential oil composition, total phenolic content, antimicrobial and antioxidant activities of Thymus vulgaris collected in five different area of the Campania Region, Southern Italy. The chemical composition of the essential oils was studied by GC-flame ionization detector (FID) and GC/MS; the biological activities were evaluated through determination of MIC and minimum bactericidal concentration (MBC) and evaluation of antioxidant activity. In total, 134 compounds were identified. The oils were mainly composed of phenolic compounds, and all oils belonged to the chemotype thymol. The antimicrobial activity of the five oils was assayed against ten bacterial strains. The oils showed different inhibitory activity against some Gram-positive pathogens. The total phenol content in the essential oils ranged from 77.6-165.1 mg gallic acid equivalents (GAE)/g. The results reported here may help to shed light on the complex chemotaxonomy of the genus Thymus. These oils could be used in many fields as natural preservatives of food and as nutraceuticals.

The chemical composition of the essential oils of Origanum vulgare ssp. hirtum, growing wild in three different localities in the Southern Apennines, was studied by GC-FID and GC/MS analyses. In total, 103 compounds were identified. The oils were mainly composed of phenolic compounds and all oils belonged to the chemotype carvacrol/thymol. The three essential oils were evaluated for their in vitro phytotoxic activity by determining their influence on the germination and initial radicle elongation of Sinapis arvensis L., Phalaris canariensis L., Lepidium sativum L., and Raphanus sativus L. The seed germination and radicle growth were affected in various degrees. Moreover, the antifungal activity of the three essential oils was assayed against three species causing pre- and postharvest fruit decay (Monilinia laxa, M. fructigena, and M. fructicola). At 1000 ppm, the three oils completely inhibited fungal growth. The hemolytic activity of the oils was assayed and showed no effect on the cell membranes of bovine erythrocytes.

Plant essential oils (EOs) are one of the most relevant natural products due to their biological, medicinal, and nutritional properties. The promising biological effects of many plants EOs encourage researchers to study their biochemical properties to be used as possible natural alternatives for commercial pesticides and not only as herbal medicines. The current research has been conducted to study the microbicide effect of Solidago canadensis L. EO to control some common plant diseases caused by several postharvest phytopathogenic fungi (Monilinia fructicola, Botrytis cinerea, Aspergillus niger, and Penicillium expansum) in comparison with Azoxystrobin as a large spectrum fungicide. The antibacterial activity has been carried out against some phytopathogenic bacteria (Bacillus megaterium and Clavibacter michiganensis (G+ve) and Xanthomonas campestris, Pseudomonas fluorescens, and Pseudomonas syringae pv. phaseolicola (G-ve)) compared to the synthetic antibiotic Tetracycline. Minimum inhibitory concentration was carried out to determine the lowest effective EO dose using a 96-well microplate. The cell membrane permeability was also evaluated by measuring the electric conductivity (EC) to examine the possible mechanisms of action of S. canadensis EO. Chemical characterization of EO has been carried out using gas chromatography and mass spectrometry (GC-MS). Thirty-two identified components in S. canadensis EO presented 97.7% of total compounds in EO. The principal compounds were identified as germacrene D (34.9%), limonene (12.5%), α-pinene (11.6%), β-elemene (7.1%), and bornyl acetate (6.3%). In addition, S. canadensis EO demonstrated promising in vitro antimicrobial activities against the majority of tested phytopathogens at all tested concentrations.

The aim was to evaluate the susceptibility of bla producing Enterobacteriaceae to Slovakian Thymus vulgaris essential oil (TVEO) alone and in combination with cefotaxime (CTX). TVEO composition was determined by gas chromatograph-mass spectrometer (GC/MS). Susceptibility to 21 antibiotics was determined by disc diffusion assay. Genes characterization for resistance to β-lactams was accomplished by polymerase chain reaction (PCR). The antibacterial activity was investigated by standard methods. The synergistic interaction was determined by checkerboard test. Thymol (34.5%), p-cymene (22.27%) and linalool (5.35%) were the major components present in the TVEO. The identified strains were multi-drug resistant (MDR). TVEO showed high activity against all MDR strains, including bla producing isolates, with inhibition zones and MIC values in the range of 24-40 mm/10μL and 2.87-11.5 μg/mL, respectively. TVEO in combination with CTX showed a synergistic action against bla producing Escherichia coli (FICI 0.28) and an additive effect vs ESBL producing Enterobacter cloacae (FICI 0.987).

Searching for new bio-based herbicides is crucial for decreasing chemical pollution, protecting the environment, and sustaining biodiversity. Origanum vulgare is considered a promising source of essential oil with herbicidal effect. The mode of action is not known. The present study focused on (1) comparison of phytotoxic activity of Origanum vulgare EO on monocot (Triticum aestivum and Hordeum vulgare) and dicot species (Lepidium sativum and Sinapis alba); (2) and evaluating other antimicrobial biological activities against phytopatogen bacteria (Clavibacter michiganensis, Pseudomonas syringae pv. phaseolicola, Pseudomonas savastanoi, and Xanthomonas campestris); antifungal activity against Monilinia fructicola, Aspergillus niger, Penicillium expansum, and Botrytis cinerea; cytotoxic activity and antioxidant activity. According to the GC/MS analyses, the EO belongs to the thymol chemotype O. vulgare with its high content of thymol (76%). Germination of all four species was not influenced by EO. The phytotoxic effect was statistically significant in the monocot species, while in the dicot species the opposite was observed—a stimulation effect, which was also statistically significant. Strong biological activity of O. vulgare EO was noted on all phytopatogen bacteria and fungi in the highest dose. Cytotoxic activity showed an IC50 = 50.5 μg/mL. Antioxidant activity showed an IC50 = 106.6 μg/mL after 45 min experimental time. Based on the presented results, it is possible to conclude that thymol chemotype O. vulgare essential oil could be potentially used as a herbicide with selective effects on monocot plant species.