Search Results (816)

The natural product composition of the hexane and methyl tert-butyl ether extracts of Dittrichia viscosa roots was examined. Eight terpenoids were identified by nuclear magnetic resonance (NMR) and high resolution mass spectroscometry (HRMS) techniques, four of which (1, 5, 6 and 8) are reported here for the first time as natural products. Of these eight compounds, four are thymol derivatives (1–4), two are guaianolides (5 and 7) and two are himachalanes (6 and 8). Additionally, the occurrence of himachalanes in this species is reported for the first time. Furthermore, a study of the potential plant protection effects of some of these natural products and the chemical derivative 6a was carried out. Promising preliminary results were obtained for compounds 1–3 and 6a as antifeedant agents against Spodoptera littoralis; 1–3 and 5 against Myzus persicae; 1–3 against Rhopalosiphum padi; and 4 as nematicide against Meloidogyne javanica. Finally, the phytotoxic activity of compounds 4, 5 and 6a against the monocotyledonous species Lolium perenne was also proven. Full article

Cannabis sativa L. leaves (CSL) are a rich in bioactive compounds and known for their medicinal and recreational uses. In this study, a natural hydrophobic deep eutectic solvent (HDES) system composed of menthol and thymol (1:1) was employed for the efficient extraction of bioactive compounds from CSL. Extraction of bioactives was optimized at various conditions involving DES/ethanol ratio, temperature, and extraction time, as well as shaking speed through statistical models including response surface methodology (RSM) and artificial neural network (ANN). The maximum bioactive yield, equal to 70% (w/w) of powdered CSL, was achieved at optimized values of 5.5 mL DES, 4.5 mL ethanol, and 225 rpm shaking speed at 55 °C for 107.5 min. It was observed that slightly adjusting the shaking speed and temperatures customized the nature of bioactives with more antioxidant, antidiabetic, and antimicrobial properties. The extracts of CSL produced while applying natural HDES were found to be non-toxic during hemolytic assay. Overall, HDES when mixed with ethanol in 55:45 ratio produced CSL extracts with an ample level of phenolics (133.75 mg GAE/g) and flavonoids (120.05 mg QE/g). GC-MS analysis of CSL extracts produced by HDES revealed the presence of multiple bioactives like tetrahydrocannabivarin, cannabidiol, cannabinol, cannabidivarol, dl-menthol, levomenthol, and 4-hydroxy-3-methylacetophenone. Based on these findings, it can be concluded that HDES in combination with ethanol may work as an efficient extraction solvent to recover CSL bioactives without compromising their antioxidant features and safety for use in food and pharmaceutical applications. Full article

Background: The control of fleas and ticks in companion animals is a persistent challenge with animal welfare and public health implications. The increasing resistance to antiparasitic treatments, coupled with concerns over the environmental impact and non-target effects of synthetic acaricides, has driven interest in sustainable alternatives. Essential oils (EOs) have emerged as potential candidates due to their complex chemistry and modes of action. Methods: This review critically analyzes the scientific literature on essential oils for ectoparasite control in companion animals. Specifically, it examines their chemical composition, multi-target mechanisms of action, laboratory and field efficacy, role in resistance mitigation, and integration into IPM strategies. Results: Several EOs, particularly those rich in phenolic compounds (thymol, carvacrol, eugenol, and cinnamaldehyde), demonstrate promising in vitro insecticidal and acaricidal activity. Their multi-target mechanisms, affecting neuronal, respiratory, and cuticular functions, not only provide efficacy but also represent a significant barrier to rapid resistance development. However, their translation to reliable field performance is hampered by high volatility, formulation instability, and innate variability. Conclusions: EOs represent a valuable source of bioactive compounds for reducing reliance on conventional acaricides and can play a key role within IPM strategies. To realize their full potential in mitigating resistance, focused advancements are needed in standardized testing, formulation science to enhance stability and residual activity, and rigorous field studies to confirm safety and efficacy. Full article

While essential oils are gaining momentum as a strategy to modulate rumen function and potentially reduce enteric methane in cattle, little is known about how their bioactive components, terpenes, affect rumen microbes. Our objective was to evaluate how in vivo doses of thymol affect the structure and function of the rumen microbial community via whole genome shotgun sequencing (WGS). Four beef steers were used in a 4 × 4 Latin square with four 28 d periods. Steers consumed ad libitum forage and received one of four thymol doses (0 [CON], 120 [120-T], 240 [240-T], and 480 [480-T] mg/kg forage intake). Rumen contents were separated into liquid and solid fractions, DNA was extracted, analyzed via WGS, and assessed with orthogonal contrasts. After FDR correction, no taxa were affected by thymol; however, raw p-values demonstrated responses to thymol supplementation for solid-associated uncultured Lachnospiraceae bacterium (p = 0.04), uncultured Methanobrevibacter (p = 0.05), and uncultured Coriobacteriaceae bacterium (p = 0.02). Liquid-associated uncultured Prevotellaceae bacterium (p = 0.03), Prevotella sp. (p = 0.04), and Bacteroides sp. (p = 0.02) also responded to thymol, with the highest abundances observed at various thymol doses. Genes involved in energy production and amino acid metabolism transport were observed at the highest abundances at 240-T, while genes associated with cell cycle control, cell division, and chromosome partitioning were present in the highest abundances at 120-T. The findings suggest that thymol exerts dose-dependent effects on rumen microbial abundances and functional pathways, with 240 mg/kg forage intake appearing to be the most effective dose to downregulate methanogenic enzymes while also enhancing the enzymes associated with metabolism without negatively impacting microbial diversity. Full article

This study investigates the phytochemical composition and biological activity of eight Thymus species distributed in Bulgaria, with a focus on taxa from section Hyphodromi. High-performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS) were used to characterize the methanolic (MeOH) and diethyl ether (Et₂O) extracts, respectively. MeOH extracts revealed high concentrations of phenolic acids, particularly rosmarinic acid, salicylic acid, and flavonoid glycosides, with T. atticus, T. jalasianus, and T. leucotrichus showing the most diverse profiles. Et₂O extracts were dominated by triterpenic acids (ursolic and oleanolic) and monoterpenes such as thymol and carvacrol, especially in T. zygioides and T. leucotrichus. All MeOH extracts exhibited significant antioxidant activity in the DPPH assay (IC₅₀ < 50 µg/mL), with T. jalasianus and T. atticus demonstrating the strongest effects. Radical scavenging potential generally followed the trend of total phenolic content. Moderate acetylcholinesterase-inhibitory activity was observed only in T. zygioides and T. leucotrichus. The study reports for the first time data on the biological activity and metabolic composition of extracts from endemic and rare species and from the species of Bulgarian origin. The results provide new data on the phytochemical composition and in vitro antioxidant and acetylcholinesterase-inhibitory activities of selected Thymus species, contributing to the characterization of their overall in vitro biochemical profiles. Full article

Background: Increasing antimicrobial resistance has directed studies toward investigating the antimicrobial activity of thymol, as well as the antibiofilm and antioxidant potential of its emulsions (with Tween 80) against multidrug-resistant (MDR) K. pneumoniae isolates. Methods: A microdilution assay was used to estimate thymol’s antibacterial potential against 10 clinical isolates (labeled 1–10). The dynamic light scattering technique was used to measure the particle size diameter (Zavg) of formulated emulsions. The antibiofilm potential of emulsions was assessed in vitro using a crystal violet assay and ex vivo on a surgical drain through a colony-forming unit assay. Antioxidant activity was screened by using the DPPH assay. Results: The MIC values were ≤1.5 mg/mL for strains 1 and 7 and <0.5 mg/mL for the other strains. Emulsions E_250:500, E_250:750, E_300:750, and E_500:750 were stable and homogeneous, with a Zavg of approx. 200 nm (128.4 ± 0.8 nm for E_250:750). These emulsions significantly reduced the biofilm biomass of strains 3 and 7 (50.6–74.32% and 34.60–59.8% of inhibition, respectively), with the strongest activity observed for E_250:500 and E_500:750. Antibiofilm potential was confirmed ex vivo, with E_500:750 showing the highest efficacy (ΔLogCFU 2.60 and 2.68 for strains 3 and 7). E_250:750 demonstrated the highest capacity to neutralize the DPPH• radical. Conclusions: Thymol and its emulsions exhibited antibacterial and antibiofilm activity against MDR K. pneumoniae isolates, along with the proven antioxidant properties of the emulsions. Full article

In this article, we report a comprehensive analysis of the chemical composition and biological activity of Dysphania ambrosioides essential oil (DA-EO) originating from Bulgaria. Gas chromatography–mass spectrometry (GC–MS) analysis led to the identification of 53 constituents, revealing a complex phytochemical profile. The results classify the investigated oil as a thymol–carvacrol chemotype, dominated by oxygenated monoterpenes (56.79%), with thymol (19.45%) and carvacrol (14.30%) as the major components. This compositional profile differs markedly from the ascaridole-rich chemotypes commonly reported in the literature. The biological activity of DA-EO was evaluated through its antimicrobial, antioxidant, and anti-inflammatory properties. The oil exhibited broad-spectrum antimicrobial activity against pathogenic microorganisms such as S. aureus, E. coli, and L. monocytogenes. Antioxidant assays (HPSA, HRSA) indicated moderate activity, closely associated with the terpenoid composition of the oil. The anti-inflammatory potential, assessed via inhibition of albumin denaturation (IAD), was analyzed using nonlinear four-parameter (4PL) and five-parameter (5PL) logistic models. The obtained IC₅₀ values (67.0–77.0 µg/mL) were comparable to those of the reference drug ibuprofen, highlighting the significant potential of DA-EO as a natural therapeutic agent. Full article

Essential oils (EOs) from combined plant materials offer a promising alternative to conventional extraction by enhancing chemical diversity and bioactivity. This study evaluated the chemical composition and insecticidal properties of individual and combined plant EOs from Cymbopogon citratus, Eucalyptus camaldulensis, Eucalyptus lehmannii, Salvia rosmarinus and Thymus vulgaris were evaluated against aphids. Binary and ternary combinations were prepared in equal proportions prior to hydrodistillation. GC-MS analysis revealed significant compositional shifts in EOs from combined plant materials. Major compounds in individual oils included citral (53.11%) and neral (29.14%) in C. citratus, thymol (70.84%) in T. vulgaris, and eucalyptol as the predominant compound in E. camaldulensis (66.51%), E. lehmannii (56.99%) and S. rosmarinus (46.56%), respectively. In the combined oils, the relative abundance of these constituents was altered, and in some cases new constituents were introduced. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) revealed that combined plant EOs clustered near their parental oils, indicating compositional inheritance. Contact toxicity assay against Aphis fabae demonstrated enhanced efficacy of the combined oils, with reduced LC₅₀ values (1.39 µL mL⁻¹ for E. camaldulensis + T. vulgaris) and synergistic interactions, indicated by a co-toxicity coefficient (CTC) of 221.58 and elevated synergistic factors. Pearson correlation analysis and Partial Least Squares (PLS) regression jointly identified Acorenone B and thymol as negatively, and caryophyllene as positively correlated compounds, all with relatively high contribution to insecticidal activity, ranking highest with a Variable Importance in Projection (VIP) scores > 1.0. While PLS model had modest predictive power, the integration of these statistical approaches supports the insecticidal potential of combined plant-derived EOS in laboratory bioassays and indicates their relevance to sustainable crop protection. Full article

The present study reports, for the first time, the chemical composition of the leaf essential oil (LEO) from Aspilia rudis as well as its antioxidant and anti-inflammatory activities. Analysis combining GC(RI), GC-MS and ¹³C-NMR of 36 samples identified 58 compounds representing 96.7–99.3% of the whole composition. Statistical analyses revealed chemical variability in three clusters, each composed of samples from the same sampling site. Cluster I is dominated by germacrene D (27.2 ± 2.7%), α-pinene (24.0 ± 2.9%) and (E)-β-caryophyllene (13.1 ± 1.7%), cluster II by α-pinene (38.9 ± 2.4%) and germacrene D (19.1 ± 3.6%), while the prevalent compound of cluster III is α-pinene (51.9 ± 5.3%), followed by β-pinene (11.7 ± 1.7%) and germacrene D (10.7 ± 2.2%). The oil samples S10, S26 and S36 demonstrated antioxidant activity (DPPH: EC₅₀ = 43.8 ± 1.0, 28.5 ± 1.0 and 38.8 ± 1.0 µg/mL, respectively; ABTS: TEAC = 17.16 ± 0.70, 23.35 ± 1.32 and 18.76 ± 0.64 µmol TE/mg EO, respectively) and anti-inflammatory activity through the LOX inhibition assay (IC₅₀ = 34.9 ± 1.0, 32.1 ± 1.0 and 22.2 ± 1.0 µg/mL, respectively). The activities of A. rudis LEO may be related to its main compounds and thymol, all known for their various pharmacological and biological properties, and probably to synergistic effects. Full article

Monoterpenes (thymol, carvacrol, menthol) and phenylpropanoids (eugenol and cinnamaldehyde) and their related derivatives are naturally occurring bioactive compounds found in essential oils (EOs) and have attracted considerable interest as anticancer agents; however, their direct therapeutic use in cancer treatment is often limited by factors such as low bioavailability, moderate potency, and lack of target specificity. Recent studies have demonstrated that rational structural modification of these EO scaffolds can substantially enhance their anticancer potential. This review critically evaluates the different structural modification strategies applied to EO components, including pharmacophore hybridization, heterocycle incorporation (e.g., triazoles, oxadiazoles, chalcones), esterification, halogenation, metal complexation, and nanoparticle conjugation. The review compares these approaches across the selected EO components, highlighting their impact on anticancer potency, and mechanistic relevance. However, the current evidence base is heterogeneous, with considerable variability in experimental conditions, selectivity assessments, and reliance on in vitro or in silico findings, which limits direct cross-study comparisons and translational interpretation. Overall, structural modification of EO components represents a promising strategy for generating novel anticancer lead compounds, but future progress will depend on standardized biological evaluation, rigorous in vivo validation, and comprehensive pharmacokinetic and toxicity profiling to realistically define their clinical potential. Full article

Toxic Cd (cadmium) pollution in agricultural soil has been drawing global attention. Using exogenous regulators to detoxify Cd in crops is a promising approach to alleviate Cd stress and prevent Cd accumulation in human bodies through the food chain. Natural compounds show great potential due to their environmentally friendly properties. We have found that thymol (a plant-derived natural compound) protects plants from Cd stress. To extend the application of thymol in agriculture, further studies are needed to understand the detailed mechanism by which thymol induces Cd tolerance and limits Cd accumulation in crops. In this study, hydroponic experiments using the roots of Brassica rapa L. exposed to a nutrient solution containing Cd (3 µM) and thymol (15 µM) were conducted to investigate the mechanism of thymol-induced Cd tolerance. Pot experiments with different vegetables (B. rapa, water spinach, and pepper) growing in Cd-polluted soil (0.5 µM Cd) were carried out to investigate the role of foliar spraying of thymol (15 µM) in decreasing the Cd content in vegetables. In the hydroponic study, thymol enhanced the shoot fresh weight and root fresh weight of B. rapa by 313% and 125%, respectively, upon Cd exposure. Thymol detoxifies Cd-induced ROS accumulation by increasing the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in B. rapa by 8.9–33.6%, 12.9–31.6%, and 57.8–135%, respectively. The thymol-activated AsA-GSH (ascorbic acid-glutathione) cycle also contributed to the decrease in ROS level. Thymol also reduced the Cd content in the shoots and roots of B. rapa by 55.7% and 46.6%, respectively, which was associated with the modulation of the expression of a set of genes accounting for Cd accumulation and transport. In the pot study, foliar spraying of thymol significantly decreased the Cd content in various vegetables, including leafy vegetables (B. rapa and two water spinach varieties, with leaf Cd decreasing by 40.5–45.9%) and solanaceous fruits and vegetables (three pepper varieties, with fruit Cd decreasing by 26.9–35.8%), which was accompanied by a growth-promoting effect. The results from this study elucidate the multifaceted function of thymol in helping vegetables detoxify Cd and decrease Cd bioaccumulation, shedding new light on developing thymol as a potential plant regulator to safeguard agroproduct security in Cd-polluted environments. Full article

We report a highly sensitive and interference-free electrochemical sensor for dopamine (DA) detection in the presence of uric acid (UA) and ascorbic acid (AA), based on an in situ deposited graphitic carbon nitride (g-C₃N₄) and polymethyl thymol blue (PMTB) nanohybrid modified screen-printed carbon electrode (SPCE). The as-fabricated g-C₃N₄/PMTB/SPCE was thoroughly characterized using various physicochemical techniques. The electrochemical behavior of the modified electrode was systematically investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The g-C₃N₄/PMTB/SPCE exhibited excellent electrocatalytic activity toward the selective oxidation of DA under optimized experimental conditions, including pH and scan rate. Interference-free detection of DA in the presence of AA and UA was achieved using DPV and chronoamperometric methods, revealing a wide linear concentration range, an ultralow limit of detection, and high sensitivity. Furthermore, the practical applicability of the proposed sensor was validated by determining DA in artificial biofluid samples, including blood serum, and urine. The recovery results obtained good agreement with those obtained using high-performance liquid chromatography (HPLC), confirming the reliability and accuracy of the developed sensing platform. Full article

Background/Objectives: Thymol (THY) is widely used in oral care products for its antimicrobial and anti-inflammatory activity, but data on its cytocompatibility, potential differential effects on oropharyngeal-derived cells, and mucosal irritation under prolonged exposure remain limited. This study evaluated THY’s effects on healthy human gingival fibroblasts (HGF-1) and pharyngeal carcinoma (Detroit-562) cells after 24 h exposure, together with its irritation potential in ovo. Methods: Cells were treated with THY (100–300 µM) for 24 h. Cellular viability (MTT), morphology, mitochondrial alterations (MitoTracker™/Hoechst 33342), mitochondrial membrane potential (JC-1), and apoptosis/necrosis (AO/PI) were assessed. Clonogenic assays evaluated long-term proliferative capacity. Lastly, irritation score was examined using the HET-CAM assay at 300 µM. Results: THY produced a dose-dependent viability decrease in both lines, with HGF-1 viability remaining ≥75% and Detroit-562 reduced to ~68% at 300 µM. Morphology, mitochondrial staining, JC-1 ratios, and AO/PI imaging showed progressive apoptotic features, more evident in Detroit-562 cells. Clonogenic capacity increased slightly in HGF-1 at 100 µM and declined to ~75% at 300 µM, whereas Detroit-562 colonies decreased from ~68% to ~40% across the dose range. Additionally, THY (300 µM) showed no irritation in the HET-CAM assay. Conclusions: THY demonstrated acceptable cytocompatibility in gingival fibroblasts, stronger inhibitory effects on carcinoma cells at higher concentrations, and no acute irritation in ovo. These findings support THY’s safe use within defined concentration limits and justify further evaluation in advanced oral tissue models. Full article

This study demonstrates the potential of Helicrisum plicatum (H. plicatum), Petroselinum crispum (P. crispum) and Origanum vulgare (O. vulgare) essential oils and their combination against four strains of two bacterial species, Listeria monocytogenes (L. monocytogenes) and Escherichia coli (E. coli), isolated from milk. GC/MS and GC/FID analyses of H. plicatum essential oil revealed α-pinene (27.61%), γ-curcumene (20.7%) and neryl acetate (5.88%) as the main compounds present in H plicatum essential oil. The main components of the essential oil of P. crispum were α-pinene (17.34%), 1,3,8-p-menthatriene (23.66%), β-phellandrene (10.41%) and myristicin (12.7%). In O. vulgare essential oil, carvacrol (58.3%), o-cymene (15.4%) and thymol (6.0%) were predominant compounds. Subsequently, an augmented simplex-centroid mixture design was applied to optimize the antibacterial efficacy of EO formulations against L. monocytogenes and E. coli. The simultaneous optimization all responses indicates that the optimal antimicrobial formulation was achieved using a ternary mixture of H. plicatum, P. crispum, and O. vulgare in a 16:16:68 (v/v/v) ratio. In parallel, an in silico study of four main essential oil components evaluated their drug-likeness, pharmacokinetic and toxicity properties, and binding to bacterial targets. These major compounds satisfy the main standards for drug-like molecules, with simulations pointing to good oral absorption, an acceptable safety profile, and stable binding to key enzymes in E. coli and L. monocytogenes, which supports their antibacterial potential. Overall, these combined experimental and computational results point to oregano, parsley, and immortelle essential oils as promising natural antimicrobial options for improving the preservation of dairy products. Full article

The work provides novel insight into the development of advanced antibacterial surfaces using the combination of essential oils, cinnamon oil, thyme oil, and tea tree oil, as well as their active compounds, including cinnamaldehyde, thymol, and terpinene-4-ol, embedded in the chitosan and sodium alginate matrix. All coatings obtained in a two-stage electrophoretic deposition process on stainless steel and titanium substrates were characterized by high adhesion strength. The microstructural differences between the coatings were mainly related to the size and location of the additives. Structural investigation showed the impact of individual oil components on intermolecular bonds between polysaccharide chains and the formation of molecular interactions in a specific spatial conformation. The surface of all coatings was minimally rough and had a hydrophilic character. A clear matrix-dependent trade-off between antibacterial efficacy and cytocompatibility was observed: alginate-based coatings achieved strong anti-Staphylococcus aureus activity (2.81 log CFU/mL) at the expense of increased cytotoxicity, while chitosan-based systems provided a more favorable cytocompatibility profile, maintaining cell viability above 70% for selected formulations. This work provides insight into the development of natural antibacterial surfaces by the combination of active compounds and shows the distinctions on many levels between the coatings with various polysaccharide matrices. Full article