Search Results (4)

The present study investigated the chemical composition of the main components of five commonly occurring Thymus species in Bulgaria: T. sibthorpii Benth., T. pulegioides L., T. glabrescens Willd. (syn. T. odoratissimus Mill.), T. callieri Borbas ex Velen. (syn. T. roegneri K. Koch), and T. zygioides Griseb. The phytochemical profiling of the Thymus species was performed using GC-MS for the analysis of essential oils and HPLC for the identification and quantification of phenolic compounds in the ethanolic extracts. Linalool was the dominant essential oil constituent in T. sibthorpii (48.17%), T. pulegioides (50.96%), and T. callieri (38.08%) while thymol prevailed in T. glabrescens (35.35%). A novel chemotype was observed in T. zygioides. The HPLC analysis confirmed rosmarinic acid as the major phenolic acid across all species. Rutin was the predominant flavonoid in four species whereas T. sibthorpii exhibited a remarkably high concentration of (+)-catechin. Overall, the high chemical diversity within the Thymus genus was confirmed. Due to the variability of compounds among plant species, the findings of the present study suggest that, along with essential oils, phenolic components may also contribute to the chemotaxonomic classification of the Thymus genus and influence the pharmacological activity of the species, which requires further study. Full article

Antimicrobial resistance is one of the drastically increasing major global health threats due to the misuse and overuse of antibiotics as traditional antimicrobial agents, which render urgent the need for alternative and safer antimicrobial agents, such as essential oils (EOs). Although the strong antimicrobial activity of various EOs has already been studied and revealed, their characteristic high sensitivity and volatility drives the need towards a more efficient drug administration method via a biomaterial system. Herein, the potential of Thymus sibthorpii EO incorporated in functionalized antibacterial collagen hydrogels was investigated. At first, the optimally stabilized type I collagen hydrogels via six different multi-arm poly (ethylene glycol) succinimidyl glutarate (starPEG) crosslinkers were determined by assessing the free amine content and the resistance to enzymatic degradation. Subsequently, 0.5, 1, and 2% v/v of EO were incorporated into optimized collagen hydrogels, and the release profile, as well as release kinetics, were studied. Finally, biomaterial cytocompatibility tests were performed. Thymus sibthorpii EO was released from the hydrogel matrix via Fickian diffusion and showed sustained release and 0.5% v/v EO-loaded hydrogels showed adequate antibacterial activity against Staphylococcus aureus and did not show any statistically significant difference compared to penicillin (p < 0.05). Moreover, none of the fabricated composite antibacterial scaffolds displayed any cytotoxicity on NIH-3T3 fibroblasts. In conclusion, this work presents an innovative antibacterial biomaterial system for tissue engineering applications, which could serve as a promising alternative to antibiotics, contributing to coping with the issue of antimicrobial resistance. Full article

GC-MS/FID analysis of the essential oils of 10 Thymus species, belonging to Sect. Serpyllum, led to identification of 118 compounds accounting for 97.79–99.69% of the total oil. Thymus moesiacus, T. jankae, T. vandasii, T. longicaulis and T. sibthorpii were characterized by the presence of linalool (19.37–35.21%) as the major or dominant component, but differed significantly in the content of the other prominent components: linalyl acetate, geraniol, geranyl acetate, α-terpinyl acetate, myrcen-8-yl acetate, myrcen-8-ol, etc. α-Terpinyl acetate (66.79%), thymol (63.96%), carvacrol (42.65%) and germacrene D (42.15%) were the principal components of T. pulegioides, T. glabrescens, T. callieri and T. pannonicus, respectively. β-Myrcene (16.53%), cis-sabinene hydrate (13.58%), τ-cadinol (13.24%) and elemol (11.29%) determined the oil from T. thracicus as a mixed mono-/sesquiterpene chemotype. The obtained results revealed the existence of new chemotypes of T. moesiacus, T. thracicus, T. sibthorpii and T. longicaulis. The essential oil content of T. callieri and endemic T. vandasii is reported for the first time. The variations in the essential oils of different Thymus species from Sect. Serpyllum were examined by principal component analysis (PCA) and cluster analysis (CA). Full article

The increase in antimicrobial resistance and tolerance over the years has become a serious public health problem, leading to the inevitable development of alternative antimicrobial agents as substitutes for industrial pharmaceutical antibiotics targeting humans and animals under the concept of one health. Essential oils (EOs) extracted from aromatic and pharmaceutical plants incorporate several bioactive compounds (phytochemicals) that positively affect human and animal health. Herein, this work aimed to examine a standardized chemical composition and screen the antimicrobial and anti-biofilm activity of Thymus sibthorpii, Origanum vulgare, Salvia fruticosa, and Crithmum maritimum EOs against three different Staphylococcus aureus strains by gold-standard disc diffusion, broth microdilution, and microtiter plate biofilm assays. Therefore, the evaluation of the above-mentioned EOs were considered as substitutes for antibiotics to combat the ever-mounting antimicrobial resistance problem. The observed bacterial growth inhibition varied significantly depending on the type and concentration of the antimicrobials. Thymus sibthorpii was determined as the strongest antimicrobial, with 0.091 mg/mL minimum inhibitory concentration (MIC) and a 14–33 mm diameter inhibition zone at 5% (v/v) concentration. All tested EOs indicated almost 95% inhibition of biofilm formation at their half MIC, while gentamicin sulfate did not show sufficient anti-biofilm activity. None of the methicillin-resistant strains showed resistance to the EOs compared to methicillin-sensitive strains. Thymus sibthorpii and Origanum vulgare could be potential alternatives as antimicrobial agents to overcome the problem of microbial resistance. The tested EOs might be incorporated into antimicrobial products as safe and potent antimicrobial and anti-biofilm agents. Full article