Biological activity of plant-based carvacrol and thymol and their impact on human health and food quality

Monoterpenoid synergy: a new frontier in biological applications

Monoterpenoids, compounds found in various organisms, have diverse applications in various industries. Their effectiveness is influenced by the oil's chemical composition, which in turn is influenced by plant genotype, environmental conditions, cultivation practices, and plant development stage. They are used in various industries due to their distinctive odor and taste, serving as ingredients, additives, insecticides, and repellents. These compounds have synergistic properties, resulting in superior combined effects over discrete ones, potentially beneficial for various health purposes. Many experimental studies have investigated their interactions with other ingredients and their antibacterial, insecticidal, antifungal, anticancer, anti-inflammatory, and antioxidant properties. This review discusses potential synergistic interactions between monoterpenoids and other compounds, their sources, and biological functions. It also emphasizes the urgent need for more research on their bioavailability and toxicity, underlining the importance and relevance of this comprehensive study in the current scientific landscape.

Composition of Sphagnum palustre L. extracts using different extraction methods

Sphagnum palustre L. is a Chinese herbal medicine with a long history, however, few studies have been performed on its chemical composition and active effects. In this study, we investigated the composition and antibacterial and antioxidant capacities of extracts obtained from Sphagnum palustre L. phytosomes extracted with conventional solvents (water, methanol, and ethanol) and two different hydrogen bond donors (citric acid and 1,2-propanediol) modified with choline chloride-type deep eutectic solvents (DESs). The results show that Sphagnum palustre extracts contained 253 compounds, including citric acid, ethyl maltol, and thymol. The highest total phenolic content (TPC) was obtained with a DES extraction method combining 1,2-propanediol and choline chloride (39.02 ± 7.08 mg gallic acid equivalent/g dried weight (DW). This shows the composition of Sphagnum palustre as a natural product and the application of DESs in the extraction of active ingredients, demonstrating the potential of peat moss extracts in cosmetics and health products.

Analytical and Antimicrobial Characterization of Zn-Modified Clays Embedding Thymol or Carvacrol

Carvacrol and thymol are broad-spectrum natural antimicrobial agents. To reduce their volatility and improve their antimicrobial performance, synergistic systems were prepared loading the active molecules in zinc-modified clays. Montmorillonite (MMT) and zeolite (ZEO) were modified with zinc ions (ZnMMT and ZnZEO), with well-known antimicrobial properties, and then with carvacrol or thymol, reaching the 26 ± 3% and 33 ± 2% w/w of loading, respectively. The resulting hybrid materials were characterized by FT-IR, XPS, XRD, TGA, and GC-MS to evaluate carvacrol/thymol release in simulating food matrices. Antimicrobial assays carried out using spoiler and pathogenic bacterial strains showed that the antimicrobial activity of both thymol and carvacrol was largely preserved once they were loaded into Zn-modified clays. However, MMT hybrids showed an antibacterial activity significantly higher than ZEO hybrids at 50 mg/mL of thymol and carvacrol. For this reason, deeper antimicrobial evaluations were carried out only for ZnMMT composites. ZnMMT loaded with thymol or carvacrol produced inhibition zones against most of the target strains, also at 3.12 mg/mL, while the positive controls represented by the single molecule thymol or carvacrol were not active. The hybrid materials can be useful for applications in which the antimicrobial activity of natural molecules need to be displayed over time as requested for the control of microbial pathogens and spoilage bacteria in different applications, such as active packaging, biomaterials, and medical devices.

Evaluation of the Antibacterial, Anti-Inflammatory, And Bone-Promoting Capacity of UiO-66 Loaded with Thymol or Carvacrol

Oral infectious diseases have a significant impact on the health of oral and maxillofacial regions, as well as the overall well-being of individuals. Carvacrol and thymol, two isomers known for their effective antibacterial and anti-inflammatory properties, have gained considerable attention in the treatment of oral infectious diseases. However, their application as topical drugs for oral use is limited due to their poor physical and chemical stability. UiO-66, a metal-organic framework based on zirconium ion (Zr4+), exhibits high drug loading capability. Carvacrol and thymol were efficiently loaded onto UiO-66 with loading rates of 79.60 ± 0.71% and 79.65 ± 0.76%, respectively. The release rates of carvacrol and thymol were 77.82 ± 0.87% and 76.51 ± 0.58%, respectively, after a period of 72 h. Moreover, Car@UiO-66 and Thy@UiO-66 demonstrated excellent antibacterial properties against Candida albicans, Escherichia coli, and Staphylococcus aureus with minimum bactericidal concentrations (MBC) of 0.313 mg/mL, 0.313 mg/mL, and 1.25 mg/mL, respectively. Furthermore, based on the results of the CCK8 cytotoxicity assay, even at concentrations as high as 1.25 mg/mL, Car@UiO-66 and Thy@UiO-66 exhibited excellent biocompatibility with a relative cell survival rate above 50%. These findings suggest that Car@UiO-66 and Thy@UiO-66 possess favorable biocompatibility properties without significant toxicity towards periodontal membrane cells. Additionally, in vivo studies confirmed the efficacy of Car@UiO-66and Thy@UiO-66 in reducing inflammation, promoting bone formation through inhibition of TNF-a and IL6 expression, enhancement of IL10 expression, and acceleration of bone defect healing. Therefore, the unique combination of antibacterial, anti-inflammatory, and osteogenic properties make Car@UiO-66 and Thy@Ui O-66 promising candidates for the treatment of oral infectious diseases and repairing bone defects.

Chemical and Bioactive Evaluation of Essential Oils from Edible and Aromatic Mediterranean Lamiaceae Plants

The Lamiaceae family, which includes several well-known aromatic plants, is scientifically relevant due to its essential oils (EOs). In this work, four EOs from Mediterranean species, namely Origanum vulgare L., Rosmarinus officinalis L., Salvia officinalis L., and Thymus vulgaris L., were evaluated for their volatile profiles and the biological activity in vitro to assess their potential use in the food and cosmetic sector. GC/MS analysis revealed dominant compounds, such as carvacrol, thymol, and eucalyptol. Regarding biological action, the samples exhibited antioxidant, cytotoxic, anti-inflammatory, antimicrobial, and antifungal activities, with O. vulgare and T. officinalis standing out. T. vulgaris showed the lowest EC50 in the reducing power assay, and O. vulgare had the lowest EC50 in the DPPH assay. Most EOs also displayed excellent anti-inflammatory responses and antifungal properties, with O. vulgare and T. vulgaris also demonstrating antibacterial activity. All EOs from Mediterranean species showed cytotoxicity against tumoral cell lines. Overall, the selected EOs stood out for their interesting bioactivities, with the obtained results underscoring their potential as natural preservatives and bioactive agents in various industrial applications, including food, pharmaceuticals, and cosmetics.

Poloxamer-Based Mixed Micelles Loaded with Thymol or Eugenol for Topical Applications

Poloxamers (P184, P188, and P407) have been investigated as the carrier system for eugenol or thymol. A synergic effect of mixed Poloxamers was proved by enhanced micellar parameters, with a lower critical micelle concentration (about 0.06 mM) and the highest surface adsorption of 9 × 10-7 mol m-2 for P188/P407. Dynamic light scattering revealed a decrease in micellar size after loading with biomolecules. Three mathematical models were applied to study the release kinetics, of which Korsmeyer-Peppas was the best fitted model. Higher relative release was observed for Poloxamer/eugenol samples, up to a value of 0.8. Poloxamer micelles with thymol were highly influential in bacterial reduction. Single P407/eugenol micelles proved to be bacteriostatic for up to 6 h for S. aureus or up to 48 h for E. coli. Mixed micelles were confirmed to have prolonged bacteriostatic activity for up to 72 h against both bacteria. This trend was also proven by the modified Gompertz model. An optimized P188/P407/eugenol micelle was successfully used as a model system for release study with a particle size of less than 30 nm and high encapsulation efficiency surpassing 90%. The developed mixed micelles were proved to have antibiofilm activity, and thus they provide an innovative approach for controlled release with potential in topical applications.

Nanostructured lipid carriers loaded with essential oils: a strategy against SARS-CoV-2

This work aimed to investigate the effectiveness of Lippia sidoides and Syzygium aromaticum essential oils (EOs) encapsulated in nanostructured lipid carriers (NLCs) as SARS-CoV-2 inhibitors through virucidal activity assessment. We developed anionic and cationic NLCs loaded with the EOs and assessed their physicochemical properties and SARS-CoV-2 virucidal activity, focusing on the effects of EO type and the NLCs composition. The NLCs exhibited particle sizes of 141.30 to 160.53 nm for anionic and 109.30 to 138.60 nm for cationic types, with PDIs between 0.16 and 0.25. High zeta potentials (>29.0 in modulus) indicated stable formulations. The NLCs effectively encapsulated the EOs, achieving encapsulation efficiencies between 84.6 to 100% w/w of marker compound. The EOs-loaded NLCs reduced the SARS-CoV-2 virion count, exceeding 2 logs over the control. NLCs loaded with Lippia sidoides and Syzygium aromaticum EOs represent an innovative strategy for combating SARS-CoV-2.

Application of essential oils as slow-release antimicrobial agents in food preservation: Preparation strategies, release mechanisms and application cases

Food spoilage caused by foodborne microorganisms will not only cause significant economic losses, but also the toxins produced by some microorganisms will also pose a serious threat to human health. Essential oil (EOs) has significant antimicrobial activity, but its application in the field of food preservation is limited because of its volatile, insoluble in water and sensitive to light and heat. Therefore, in order to solve these problems effectively, this paper first analyzed the antibacterial effect of EOs as an antimicrobial agent on foodborne bacteria and its mechanism. Then, the application strategies of EOs as a sustained-release antimicrobial agent in food preservation were reviewed. On this basis, the release mechanism and application cases of EOs in different antibacterial composites were analyzed. The purpose of this paper is to provide technical support and solutions for the preparation of new antibacterial packaging materials based on plant active components to ensure food safety and reduce food waste.

The In Vitro Antibacterial Activity of Phytogenic and Acid-Based Eubiotics against Major Foodborne Zoonotic Poultry Pathogens

The aim of the study was to investigate in vitro the antibacterial activity of 8 commercial drinking water additives against major zoonotic poultry pathogens (Campylobacter spp., Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and Listeria spp.). We tested two essential oil-based phytogenics (Phyto CSC Liquide B, AEN 350 B Liquid), two acid-based eubiotics (Salgard® liquid, Intesti-Flora), and four blends of essential oils and organic acids (ProPhorceTM SA Exclusive, Herbal acid, Rigosol-N and Eubisan 3000). The antibacterial activity was determined by estimating the minimum inhibitory concentration (MIC) using a microdilution method. The MICs of the products against Campylobacter spp. ranged from 0.071% to 0.568% v/v, in which Herbal acid, a blend rich in lactic and phosphoric acids, also containing thyme and oregano oils, exhibited the highest efficacy (MIC: 0.071% v/v) against all the tested strains. The MICs of the tested products against Escherichia coli ranged between 0.071% and 1.894% v/v. Specifically, the MIC of Rigosol-N, a blend of high concentrations of lactic and acetic acid, was 0.142% v/v for both tested strains, whereas the MICs of Intesti-Flora, a mixture rich in lactic and propionic acid, ranged from 0.284% to 0.568% v/v. The MICs of the products against Salmonella Typhimurium were between 0.095% and 1.894% v/v. Specifically, the MIC of Eubisan 3000, a blend rich in oregano oil, was 0.284% v/v. The MICs against Staphylococcus aureus were between 0.142% and 9.090% v/v. The MICs of Phyto CSC Liquide B, which is rich in trans-cinnamaldehyde, were between 3.030% and 9.090% v/v, showing the highest MIC values of all tested products. Finally, the MIC values of the tested commercial products against Listeria spp. were 0.095% to 3.030% v/v. The MICs of ProPhorceTM SA Exclusive, a highly concentrated blend of formic acid and its salts, were 0.095-0.142% v/v against Listeria spp., while the MICs of AEN 350 B Liquid were between 0.284% and 1.894% exhibiting high Listeria spp. strain variability. In conclusion, all the selected commercial products exhibited more or less antibacterial activity against pathogenic bacteria and, thus, can be promising alternatives to antibiotics for the control of zoonotic poultry pathogens and the restriction of antimicrobial-resistant bacteria.

Carvacrol and thymol effect in vapor phase on Escherichia coli and Salmonella serovar Typhimurium growth inoculated in a fresh salad

This study aimed to evaluate the antimicrobial effect of thymol and carvacrol in inhibiting Escherichia coli and Salmonella serovar Typhimurium inoculated on a fresh green salad through the vapor phase. A film-forming solution was prepared by dissolving starch, sorbitol, and variying concentrations of carvacrol, thymol, and a mixture of both. The film-forming solution containing the respective antimicrobial agent was then added lid, which was sealed rigidly and hermetically to achieve different concentrations (105 mg/L of air of carvacrol, 105 mg/L of air of thymol, and a mixture of 52 mg/L of air of carvacrol and 52 mg/L of air of thymol). Each active package contained fresh green salad inoculated with E. coli or Salmonella serovar Typhimurium. The active packages were then sealed and refrigerated at a temperature of 6 °C for 48 h. Growth/inhibition curves were modelled using the Weibull equation, and consumer acceptance was evaluated. Carvacrol can reduce up to 0.5 log-cycles, while thymol can reach almost 1 log cycle. Blending the components with half the concentration has a synergistic effect, inhibiting up to 2.5 log cycles. Consumer ratings revealed no significant differences between the packages. However, the average score was 5.4 on a 9-point hedonic scale, evaluators' comments did not indicate dislike or a strong taste characteristic of thymol and carvacrol.

Carvacrol and Thymol Hybrids: Potential Anticancer and Antibacterial Therapeutics

Cancer is ranked among lethal diseases globally, and the increasing number of cancer cases and deaths results from limited access to effective therapeutics. The use of plant-based medicine has been gaining interest from several researchers. Carvacrol and its isomeric compound, thymol, are plant-based extracts that possess several biological activities, such as antimalarial, anticancer, antifungal, and antibacterial. However, their efficacy is compromised by their poor bioavailability. Thus, medicinal scientists have explored the synthesis of hybrid compounds containing their pharmacophores to enhance their therapeutic efficacy and improve their bioavailability. Hence, this review is a comprehensive report on hybrid compounds containing carvacrol and its isomer, thymol, with potent anticancer and antibacterial agents reported between 2020 and 2024. Furthermore, their structural activity relationship (SAR) and recommended future strategies to further enhance their therapeutic effects will be discussed.

Exploring low-dose gamma radiation effects on monoterpene biosynthesis in Thymus vulgaris: insights into plant defense mechanisms

Thymus vulgaris, commonly known as thyme, is a plant renowned for producing monoterpenes. This study aimed to understand the effects of low-dose gamma radiation, specifically in the range of 1-5 Gy, on various traits of Thymus vulgaris, providing context on its importance in agricultural and medicinal applications. The research explored morpho-physiological, biochemical, and gene-expression responses in thyme plants under no gamma- and gamma-ray exposure conditions. The study revealed complex relationships between gamma-ray doses and plant characteristics. In particular, shoot and root lengths initially increased with low doses (1-3 Gy) but decreased at higher doses (5 Gy), suggesting a dose-dependent threshold effect. Similarly, shoot and root fresh weights displayed an initial increase followed by a decline with increasing doses. Biochemical parameters showed dose-dependent responses, with low to moderate doses (1-3 Gy) stimulating enzyme activities and high doses (5 Gy) inhibiting them. Gene expression analysis was focused on the following specific genes: thymol synthase, γ-terpinene synthase, and carvacrol synthase. Low to moderate doses increased the expression of these genes, resulting in increased production of bioactive compounds. However, higher doses had diminished effects or suppressed gene expression. Metabolite analysis demonstrated dose-dependent responses, with moderate doses enhancing secondary metabolite production, while higher doses provided limited benefits. These findings underscore the implications of using gamma radiation to enhance secondary metabolite production in plants and its potential applications in agriculture, medicine, and environmental science. The study emphasizes the potential of gamma radiation as an external stressor to influence plant responses and highlights the importance of understanding such effects in various fields.

Robust construction of konjac glucomannan/polylactic acid nanofibrous films incorporated with carvacrol via microfluidic blow spinning for food packaging

In recent years, the application of biopolymer-based nanofibers prepared via microfluidic blow spinning (MBS) for food packaging has continuously increased due to their advantages of biocompatibility, biodegradability, and safety. However, the poor spinnability, undesirable water barrier capacity, and loss of antibacterial and antioxidant properties of biopolymer-based nanofibers strictly restrict their real-world applications. In this work, carvacrol (CV) incorporated konjac glucomannan (KGM)/polylactic acid (PLA) nanofibrous films (KP-CV) were produced by MBS. The FTIR spectra and XRD analysis revealed the hydrogen bonding interactions among CV, PLA, and KGM, thus significantly improving the TS of KP-CV nanofibrous films from 0.23 to 1.27 MPa with increased content of CV from 0 % to 5 %. Besides, KP-CV nanofibrous films showed improved thermal stability, excellent hydrophobicity (WCA: 128.19°, WVP: 1.02 g mm/m2 h kPa), and sustained release of CV combined with good antioxidant activities (DPPH radical scavenging activity: 77.51 ± 1.57 %), and antibacterial properties against S. aureus (inhibition zone: 26.33 mm) and E. coli (inhibition zone: 22.67 mm). Therefore, as prepared KP-CV nanofibrous films can be potentially applied as packaging materials for the extended shelf life of cherry tomatoes.

The use of essential oils in atopic dermatitis: a review

Atopic dermatitis (AD) has become a common childhood disease that affects a large number of children worldwide and has become a chronic skin disease that causes huge economical and psychological damage to the whole family. Despite the use of steroids, immunosuppressants, and various topical preparation, the prognosis is still poor. Hence, this review aimed to explore the potential of using essential oils (EO) as an active ingredient in managing AD. The review was completed by using Pubmed, Scopus, and Medline to search for relevant articles that study the pathophysiology of AD, the properties of EO, the use of EO in managing AD, and the suitable advanced formulation to incorporate EO. From the review conducted, it was concluded that EO have huge potential in managing AD and can be used as complimentary therapeutic agents in AD treatment. Scientists and industries should venture into commercializing more topical products with EO to help manage AD more effectively.

Comparative toxicological evaluation of carvacrol, acetylcarvacrol anda fipronil-based pesticide in human blood cells

Plant-derived chemicals are promising substances to control arthropod pests, although synthetic ones are still the most frequently used. Thus, comparative toxicological studies are needed to determine if natural substances are safe alternatives to replace the use of synthetic chemicals. This study aimed to compare the toxicity of carvacrol (natural origin), acetylcarvacrol (semi-synthetic) and a fipronil-based pesticide (synthetic). We assessed the effects of these chemicals on hemolytic activity, erythrocytes morphology and leucocyte viability using whole blood from human subjects. Additionally, DNA damage was evaluated through comet and DNA fragmentation assays. Fipronil and carvacrol caused hemolysis at concentrations ranging from 0.5 to 2.0%, whereas acetylcarvacrol did not cause hemolysis at 0.5 and 0.75%. Fipronil and carvacrol caused severe alterations in erythrocytes' morphology at 2%, such as ghost erythrocytes, elliptocyte-like shape and rouleau-like shape, presenting only 3.3 and 8.3% normal cells, respectively, at this concentration. However, 73.3% erythrocytes incubated with 2% acetylcarvacrol exhibited normal morphology. Fipronil considerably reduced leucocytes viability, decreasing it to 78% at 2%. Carvacrol and acetylcarvacrol showed no differences in leucocyte viability for 0.5 to 1.0%, but a decrease was observed for 2% carvacrol. The comet assay showed similar DNA damage for fipronil and carvacrol, but it was significantly lower for 1 and 2% acetylcarvacrol. Incubation with genomic DNA showed that only fipronil caused fragmentation of this molecule. Thus, we conclude that carvacrol and fipronil can present similar toxicity at higher concentrations. However, acetylation of carvacrol significantly reduced its toxicity to human blood cells compared with the other chemicals.

Natural-based edible nanocomposite coating for beef meat packaging

Researchers have made significant discoveries in addressing the limitations of essential oils (EOs) in food packaging using encapsulation systems combined with nanoparticles (NPs). This study aimed to develop a unique coating for beef preservation using nanostructured lipid carriers (NLCs). The optimal formulation of NLCs was determined based on size, zeta potential, and loading rate, achieving a content of 71.4% savory EO. A composite coating containing NPs was then created using different concentrations of NLCs (0, 0.85%, 1.7%, 2.55%, and 3.4%). The antimicrobial effectiveness of the coatings was assessed using well-diffusion assays to identify the best coating (17 mm). This optimized coating was applied to beef samples for 12 days, and extensive evaluation was conducted over time. The results demonstrated that the encapsulation percentage was higher than 98.7%. The optimal coating (CMC-OM-ZnO NPs-NLCs 3.4%) significantly reduced microbial growth (total count: over 1.6 log CFU/g), pH, thiobarbituric acid value (TBA), and total volatile nitrogen (TVN) compared with the control samples (P < 0.05). Overall, this novel bioactive packaging enriched with lipidic and inorganic nanomaterials represents an innovative way to improve meat products' oxidative and microbial stability.

Inhalation of Citrus Reticulata essential oil alleviates airway inflammation and emphysema in COPD rats through regulation of macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory respiratory disease. Citrus Reticulata peel, the dried ripe peel of Citrus Reticulata species, has been found to have anti-inflammatory and cough attenuation effects. However, the therapeutic effects and its precise underlying mechanisms of atomizing inhalation using Citrus Reticulata essential oil (CREO) have not yet been fully elucidated.

AIM OF THE STUDY

The aim of this study was to assess the therapeutic effects of Citrus Reticulata essential oil and its associated anti-inflammatory mechanisms in COPD rat model.

METHODS

A total of 80 SD rats were randomized into four groups: control group (Con), COPD model group (COPD), COPD + ipratropium bromide (IB), and COPD + citrus reticulata essential oil (CREO). To induce COPD in rats, cigarette smoke (CS) exposure was used, while CREO and IB groups were administered through atomizing inhalation. The clinical signs, pathological lesions of the lung, percentages of antigen-presenting lung macrophages (CD11b/c+/CD86+ cells) and CD8+ T cells, and the content and mRNA expression of cytokines of the lung were analyzed.

RESULTS

The findings revealed that atomizing inhalation of Citrus reticulata essential oil had therapeutic effects on COPD rats. The treatment resulted in improvement in the body weight and mental status of COPD rats, reduced pathological injury of the lung, and increased proportion of CD11b/c+/CD86+ cells in lung macrophages, while also decreasing the number of CD8+ T cells. In addition, the Citrus Reticulata essential oil reduced the contents of IL-18, IL-17A, IL-12p70, and GM-CSF, downregulated the relative mRNA expression of IFN-γ, IL-4, and MMP-12, and upregulated the mRNA expression of IL-10.

CONCLUSIONS

Citrus reticulata essential oil can alleviate histological injury of the lung and regulate macrophages and CD8+ T cells in COPD rats. The study suggests that citrus reticulata essential oil could be a potential therapeutic agent for COPD.

Influence of myoglobin on the antibacterial activity of carvacrol and the binding mechanism between the two compounds

BACKGROUND

Myoglobin (MB), a pigmentation protein, can adversely affect the antibacterial activity of carvacrol (CAR) and weaken its bacteriostasis effect. This study aimed to clarify the influence of MB on the antibacterial activity of CAR and ascertain the mechanism involved in the observed influence, especially the interaction between the two compounds.

RESULTS

Microbiological analysis indicated that the presence of MB significantly suppressed the antibacterial activity of CAR against Listeria monocytogenes. Ultraviolet-visible spectrometry and fluorescence spectroscopic analysis confirmed the interaction between CAR and MB. The stoichiometric number was determined as ~0.7 via double logarithmic Stern-Volmer equation analysis, while thermodynamic analysis showed that the conjugation of the two compounds occurred as an exothermal reaction (ΔH° = -32.3 ± 11.4 kJ mol-1 and ΔS° = -75 J mol-1  K-1 ). Circular dichroism, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy showed hydrogen bonding in the carvacrol-myoglobin complex (CAR-MB). Molecular docking analysis confirmed that amino acid residues, including GLY80 and HIS82, were most likely to form hydrogen bonds with CAR, while hydrogen bonds represented the main driving force for CAR-MB formation.

CONCLUSION

CAR antibacterial activity was significantly inhibited by the presence of MB in the environment due to the notable reduction in the effective concentration of CAR caused by CAR-MB formation. © 2023 Society of Chemical Industry.

Green Starch-Based Hydrogels with Excellent Injectability, Self-Healing, Adhesion, Photothermal Effect, and Antibacterial Activity for Promoting Wound Healing

Hydrogel materials have proven valuable in wound healing, but improving the safety of these hydrogels is still challenging. Therefore, designing multifunctional natural polymeric-based hydrogels with excellent mechanical properties to replace toxic or potentially risky, refractory chemical polymer-based hydrogels such as polyacrylamide and polyethylene glycol is of particular significance. Here, a green starch-based hydrogel (Starch@Ca/CGC hydrogel) with injectability, self-healing, and instant adhesion was constructed by coordination interaction, electrostatic interaction, and intramolecular and intermolecular hydrogen bonds. Therein, natural bioactive small molecules gallic acid (GA) and carvacrol (CA) were coordinated with metal ions by the ultrasonic-triggered self-assembly and ionic cross-linking codriven strategy to prepare Cu-gallic acid-carvacrol nanospheres (CGC NPs), which conferred the hydrogel with near-infrared light (NIR)-controlled CA release and photothermal synergistic sterilization properties, as well as antioxidant and anti-infection capabilities. More importantly, the multifunctional hydrogel platforms could completely cover an irregular wound shape to prevent secondary injury and significantly accelerate wound healing under NIR with more skin appendages like hair follicles and blood vessels appearing. Therefore, it is expected that this starch-based hydrogel could serve as a competitive multifunctional dressing in the biomedical field, including bacteria-derived wound infection and other tissue repair.

Thymol incorporation within chitosan/polyethylene oxide nanofibers by concurrent coaxial electrospinning and in-situ crosslinking from core-out for active antibacterial packaging

Active packaging systems that are sustainable and capable of delivering antimicrobial agents are in demand in food industry. In this work, Thymol (Thy) was encapsulated into Polyethylene oxide (PEO)/Chitosan (CS) to form core-shell nanofibers via coaxial electrospinning. Various dose of the crosslinker-genipin (GP) were encapsulated into the core layer to achieve in-situ etching crosslink with the CS of shell layer during the electrospinning process. The core-shell structure of the nanofiber was confirmed by transmission electron microscopy. The microstructures, mechanical properties, water vapor permeability, swelling ratios, wettability, thermal stability, biocompatibility and antibacterial properties of the crosslinked films were characterized. The results showed that the crosslinked films had compact structures, strong water resistance, better mechanical property and thermal stability, the sustained release profiles and antioxidant activity were also improved. More importantly, the antibacterial assays indicated that the Thy loaded nanofiber films could effectively inhibit the growth of two common food spoilage bacteria-E. coli and S. aureus.

Investigation of physicochemical and biological properties of bacterial cellulose & zein-reinforced edible nanocomposites based on flaxseed mucilage containing Origanum vulgare L. essential oil

In the present study, the effect of zein and different amounts of bacterial cellulose (BC; 1, 2 and 3 wt%) on the physical, mechanical and barrier properties of flaxseed mucilage/carboxymethyl cellulose (FM/CMC) composite was investigated. The appearance of the absorption band at 1320cm-1 in the ATR-FTIR spectra of nanocomposites indicated the successful introduction of zein into their structure. The characteristic peak at 2θ of 9° belonging to zein disappeared in XRD patterns of the prepared composites suggesting the successful coating of zein via hydrogen bonding interactions. SEM images proved the formation of semi-spherical zein microparticles in the FM/CMC matrix. TGA plots ascertained the addition of zein and nanocellulose caused a significant increase in the thermal stability of FM/CMC film, although zein showed a greater effect. The presence of zein and nanocellulose increased the mechanical strength of nanocomposites. The WVP of FM/CMC decreased after the incorporation of zein and nanocellulose, which created a tortuous path for the diffusion of water molecules. The zein particles exhibited a greater influence on improving the mechanical and barrier properties compared to nanocellulose. FM/CMC-Z film exhibited the highest mechanical strength (49.07 ± 5.89 MPa) and the lowest WVP (1.179 ± 0.076). The composites containing oregano essential oil (EO) showed higher than 60 % antibacterial properties. The bactericidal efficiency of FM/CMC/Z-EO and FM/CMC/Z-EO/BC1 nanocomposites decreased about 10% compared to FM/CMC/EO and FM/CMC-Z/BC1. This evidenced the successful encapsulation of EO molecules in zein particles. According to the in vitro release study, entrapment of EO into zein particles could delay the release and provide the extended antimicrobial effect.

Inhibitory Effects of Carvacrol on Biofilm Formation in Colistin Heteroresistant Acinetobacter baumannii Clinical Isolates

BACKGROUND

The ability of bacteria to form biofilm is an essential strategy for creating stable infections. This issue is more critical in Acinetobacter bauamannii as a hospital pathogen. Today, the control of biofilm formation and solutions to prevent or remove biofilm is being developed. Carvacrol has been considered an anti-biofilm compound in significant bacteria. This study investigated the anti-biofilm effect of Carvacrol on biofilm formation in clinical colistin heteroresistant isolates of A. baumannii.

METHODS

22 clinical strains of A. baumannii were collected from Motahari Hospital in Tehran, Iran, in 2019. Biochemical and genotypic methods confirmed these isolates. Colistin heteroresistance was determined by the Standard PAP method. Carvacrol's antibacterial and anti-biofilm activity was determined according to the standard protocol.

RESULTS

About 12 isolates were considered strong biofilm producers and were used for analysis. Six isolates had hetero-resistance to colistin. Carvacrol at a 512 g/ml concentration showed the best antibacterial activity against all isolates. The sub-MIC of Carvacrol (256 g/ml) reduced the biofilm formation capacity, which was statistically significant (p < 0.05).

CONCLUSION

The results of this study showed that sub-MIC of Carvacrol has anti-biofilm effects in clinical A.baumannii colistin hetero-resistance isolates.

Traditional Knowledge Evolution over Half of a Century: Local Herbal Resources and Their Changes in the Upper Susa Valley of Northwest Italy

Susa Valley, located in the Italian Western Alps, has served as a meeting point for cultural, spiritual, and commercial exchange for a long period of history. The valley's role as one of the main connecting routes between south and southwestern Europe resulted in its acquisition of a rich traditional ecological knowledge. However, like other Italian mountainous valleys, this valley has suffered from abandonment and depopulation in the past 50 years. Our study aims to investigate the current ethnobotanical medicinal knowledge in the valley and to compare our findings with a study conducted over 50 years ago in the same area. In 2018, we conducted 30 in-depth semi-structured interviews on medicinal plants and food-medicines used in the Susa Valley. We documented 36 species, of which 21 species were used for medical purposes and 15 species were used as food-medicine. The comparison with the previous study on medicinal herbs conducted in 1970 in the valley demonstrated a significant decrease in both the knowledge and use of medicinal plants, which could be attributed to socioeconomic, cultural, and possibly environmental changes that occurred in the past half-century. Our study highlights several promising species for future use as nutraceuticals, food, and medicinal products, such as Taraxacum officinale, Urtica dioica, and Artemisia genipi.

Carvacrol Reduces Mercuric Chloride-Induced Testicular Toxicity by Regulating Oxidative Stress, Inflammation, Apoptosis, Autophagy, and Histopathological Changes

Mercuric chloride (HgCl2) is a heavy metal that is toxic to the human body. Carvacrol (CAR) is a flavonoid found naturally in plants and has many biological and pharmacological activities including anti-inflammatory, antioxidant, and anticancer activities. This study aimed to investigate the efficacy of CAR in HgCl2-induced testicular tissue damage. HgCl2 was administered intraperitoneally at a dose of 1.23 mg/kg body weight alone or in combination with orally administered CAR (25 mg/kg and 50 mg/kg body weight) for 7 days. Biochemical and histological methods were used to investigate oxidative stress, inflammation, apoptosis, and autophagy pathways in testicular tissue. CAR treatment increased HgCl2-induced decreased antioxidant enzyme (SOD, CAT, and GPx) activities and GSH levels. In addition, CAR reduced MDA levels, a marker of lipid peroxidation. CAR decreased the levels of inflammatory mediators NF-κB, TNF-α, IL-1β, COX-2, iNOS, MAPK14, MAPK15, and JNK. The increases in apoptotic Bax and Caspase-3 with HgCl2 exposure decreased with CAR, while the decreased antiapoptotic Bcl-2 level increased. CAR reduced HgCl2-induced autophagy damage by increasing Beclin-1, LC3A, and LC3B levels. Overall, the data from this study suggested that testicular tissue damage associated with HgCl2 toxicity can be mitigated by CAR administration.

Natural products as anthelmintics: safeguarding animal health

Covering literature to December 2022This review provides a comprehensive account of all natural products (500 compounds, including 17 semi-synthetic derivatives) described in the primary literature up to December 2022, reported to be capable of inhibiting the egg hatching, motility, larval development and/or the survival of helminths (i.e., nematodes, flukes and tapeworms). These parasitic worms infect and compromise the health and welfare, productivity and lives of commercial livestock (i.e., sheep, cattle, horses, pigs, poultry and fish), companion animals (i.e., dogs and cats) and other high value, endangered and/or exotic animals. Attention is given to chemical structures, as well as source organisms and anthelmintic properties, including the nature of bioassay target species, in vivo animal hosts, and measures of potency.

The performance of plant essential oils against lactic acid bacteria and adverse microorganisms in silage production

Plant essential oils have played an important role in the field of antibiotic alternatives because of their efficient bacteriostatic and fungistatic activity. As plant essential oils are widely used, their activity to improve the quality of plant silage has also been explored. This review expounds on the active ingredients of essential oils, their bacteriostatic and fungistatic activity, and mechanisms, as well as discusses the application of plant essential oils in plant silage fermentation, to provide a reference for the development and application of plant essential oils as silage additives in plant silage fermentation feed.

Inhibition of Acinetobacter baumannii Biofilm Formation by Terpenes from Oregano (Lippia graveolens) Essential Oil

Acinetobacter baumannii is a nosocomial pathogen known for its ability to form biofilms, leading to persistent infections and antibiotic resistance. The limited effective antibiotics have encouraged the development of innovative strategies such as using essential oils and their constituents. This study evaluated the efficacy of oregano (Lippia graveolens) essential oil (OEO) and its terpene compounds, carvacrol and thymol, in inhibiting A. baumannii biofilms. These treatments showed a minimum inhibitory concentration of 0.6, 0.3, and 2.5 mg/mL and a minimum bactericidal concentration of 1.2, 0.6, and 5 mg/mL, respectively. Sub-inhibitory doses of each treatment and the OEO significantly reduced biofilm biomass and the covered area of A. baumannii biofilms as measured by fluorescence microscopy. Carvacrol at 0.15 mg/mL exhibited the most potent efficacy, achieving a remarkable 95% reduction. Sub-inhibitory concentrations of carvacrol significantly reduced the biofilm formation of A. baumannii in stainless steel surfaces by up to 1.15 log CFU/cm2 compared to untreated bacteria. The OEO and thymol exhibited reductions of 0.6 log CFU/cm2 and 0.4 log CFU/cm2, respectively, without affecting cell viability. Moreover, the terpenes inhibited twitching motility, a crucial step in biofilm establishment, with carvacrol exhibiting the highest inhibition, followed by OEO and thymol. The study provides valuable insights into the potential of terpenes as effective agents against A. baumannii biofilms, offering promising avenues for developing novel strategies to prevent persistent infections and overcome antibiotic resistance.

Effects of Thyme Essential Oil Microcapsules on the Antioxidant and Quality Characteristics of Mutton Patties

This study aimed to assess the stability of thyme essential oil microcapsules (TEOMs) and their impacts on the antioxidant properties and quality of lamb patties. The results demonstrated that gum Arabic effectively enhanced the stability of phenols within the thyme essential oil (TEO), with an optimal core/wall ratio of 1:8. Substituting TEO with TEOMs in lamb patties led to reductions in the thiobarbituric acid content, carbonyl content, sulfhydryl loss, and protein cross-linking. Additionally, the TEOMs positively influenced the mutton patties' color, texture, microbiological stability, and sensory attributes. These findings substantiate the idea that TEOMs exhibit significant potential as a natural preservative to enhance the quality of mutton patties.

Phytochemical Composition and Pharmacological Activities of Three Essential Oils Collected from Eastern Morocco (Origanum compactum, Salvia officinalis, and Syzygium aromaticum): A Comparative Study

Throughout history, essential oils have been employed for their pleasing scents and potential therapeutic benefits. These oils have shown promise in various areas, including aromatherapy, personal care products, natural remedies, and even as alternatives to traditional cleaning agents or pest control solutions. The study aimed to explore the chemical makeup, antioxidant, and antibacterial properties of Origanum compactum Benth., Salvia officinalis L., and Syzygium aromaticum (L.) Merr. et Perry. Initially, the composition of the three essential oils, O. compactum (HO), S. officinalis (HS), and S. aromaticum (HC) was analyzed using GC-MS technology, revealing significant differences in the identified compounds. α-thujone emerged as the predominant volatile component in the oils, making up 78.04% of the composition, followed by eugenol, which constituted 72.66% and 11.22% of the HC and HO oils, respectively. To gauge antioxidant capabilities, tests involving DPPH scavenging capacity and total antioxidant capacity were conducted. Antioxidant activity was determined through the phosphomolybdate test and the DPPH• radical scavenging activity, with the HO essential oil displaying significant scavenging capacity (IC50 of 0.12 ± 0.02 mg/mL), similar to ascorbic acid (IC50 of 0.26 ± 0.24 mg/mL). Similarly, the TAC assay for HO oil revealed an IC50 of 1086.81 ± 0.32 µM AAE/mg. Additionally, the oils' effectiveness against four bacterial strains, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Listeria monocytogenes, and five fungi, Geotrichum candidum, Aspergillus niger, Saccharomyces cerevisiae, Candida glabrata, and Candida albicans, was tested in vitro. The examined essential oils generally exhibited limited antimicrobial effects, with the exception of HC oil, which demonstrated an exceptionally impressive level of antifungal activity. In order to clarify the antioxidant, antibacterial, and antifungal effects of the identified plant compounds, we employed computational methods, specifically molecular docking. This technique involved studying the interactions between these compounds and established protein targets associated with antioxidant, antibacterial, and antifungal activities.

Essential Oils and Their Combination with Lactic Acid Bacteria and Bacteriocins to Improve the Safety and Shelf Life of Foods: A Review

The use of plant extracts (e.g., essential oils and their active compounds) represents an interesting alternative to chemical additives and preservatives applied to delay the alteration and oxidation of foods during their storage. Essential oils (EO) are nowadays considered valuable sources of food preservatives as they provide a healthier alternative to synthetic chemicals while serving the same purpose without affecting food quality parameters. The natural antimicrobial molecules found in medicinal plants represent a possible solution against drug-resistant bacteria, which represent a global health problem, especially for foodborne infections. Several solutions related to their application on food have been described, such as incorporation in active packaging or edible film and direct encapsulation. However, the use of bioactive concentrations of plant derivatives may negatively impact the sensorial characteristics of the final product, and to solve this problem, their application has been proposed in combination with other hurdles, including biocontrol agents. Biocontrol agents are microbial cultures capable of producing natural antimicrobials, including bacteriocins, organic acids, volatile organic compounds, and hydrolytic enzymes. The major effect of bacteriocins or bacteriocin-producing LAB (lactic acid bacteria) on food is obtained when their use is combined with other preservation methods. The combined use of EOs and biocontrol agents in fruit and vegetables, meat, and dairy products is becoming more and more important due to growing concerns about potentially dangerous and toxic synthetic additives. The combination of these two hurdles can improve the safety and shelf life (inactivation of spoilage or pathogenic microorganisms) of the final products while maintaining or stabilizing their sensory and nutritional quality. This review critically describes and collects the most updated works regarding the application of EOs in different food sectors and their combination with biocontrol agents and bacteriocins.

Spice-Derived Phenolic Compounds: Potential for Skin Cancer Prevention and Therapy

Skin cancer is a condition characterized by the abnormal growth of skin cells, primarily caused by exposure to ultraviolet (UV) radiation from the sun or artificial sources like tanning beds. Different types of skin cancer include melanoma, basal cell carcinoma, and squamous cell carcinoma. Despite the advancements in targeted therapies, there is still a need for a safer, highly efficient approach to preventing and treating cutaneous malignancies. Spices have a rich history dating back thousands of years and are renowned for their ability to enhance the flavor, taste, and color of food. Derived from various plant parts like seeds, fruits, bark, roots, or flowers, spices are important culinary ingredients. However, their value extends beyond the culinary realm. Some spices contain bioactive compounds, including phenolic compounds, which are known for their significant biological effects. These compounds have attracted attention in scientific research due to their potential health benefits, including their possible role in disease prevention and treatment, such as cancer. This review focuses on examining the potential of spice-derived phenolic compounds as preventive or therapeutic agents for managing skin cancers. By compiling and analyzing the available knowledge, this review aims to provide insights that can guide future research in identifying new anticancer phytochemicals and uncovering additional mechanisms for combating skin cancer.

The Effect of Ripening Stages on the Accumulation of Polyphenols and Antioxidant Activity of the Fruit Extracts of Solanum Species

The aim of the research was to evaluate the influence of the ripening stage on the accumulation of polyphenols and antioxidant activity in fruits of Solanum species. The experiment included two factors: I-four different Solanum species (S. melanocerasum, S. nigrum, S. villosum, and S. retroflexum) and II-three ripening stages. High-performance liquid chromatography (HPLC) was used to analyze the individual phenolic compounds (flavonoids and phenolic acids), and the spectrophotometric method was applied to determine antioxidant activity. The results revealed that the accumulation of polyphenols and antioxidant activity in fruits of Solanum species depends on the stage of ripening and species. All studied Solanum species fruits had the highest content of total phenolic acid at ripening stage III and the greatest antioxidant activity at ripening stage I. Fully ripe fruits of S. melanocerasum contained significantly more total flavonoids, whereas S. nigrum contained significantly more total phenolic acids than other investigated Solanum species fruits. The significantly highest antioxidant activity was found in S. melanocerasum fruits at ripening stage I.

Essential Oil Composition and Antioxidant Activity of Oregano and Marjoram as Affected by Different Light-Emitting Diodes

Oregano and marjoram are important aromatic spices in the food industry, as well as medicinal plants with remarkable antioxidant properties. Despite their popularity, little is known about treatments that would influence the antioxidant capacity of essential oils. In this study, different spectra of LED light, namely blue, red, white, blue-red, and natural ambient light as a control, were applied to assess the essential oil content, composition, flavonoid, phenolic, and antioxidant capacity of oregano and marjoram. GC-MS analysis revealed thymol, terpinen-4-ol, sabinene, linalool, p-cymene, and γ-terpinene as the main compounds. In oregano, the thymol content ranged from 11.91% to 48.26%, while in marjoram it varied from 17.47% to 35.06% in different samples. In oregano and marjoram, the highest phenolic contents were in blue (61.26 mg of tannic acid E/g of DW) and in white (65.18 mg of TAE/g of DW) light, respectively, while blue-red illumination caused the highest increase in total flavonoids. The antioxidant activity of oregano and marjoram extract was evaluated using two food model systems, including DPPH and β-carotene bleaching. The highest antioxidant capacity was obtained in control light in oregano and blue-red light in marjoram. The results provide information on how to improve the desired essential oil profile and antioxidant capacity of extracts for industrial producers.

Antifungal and Antibiofilm Activity of Colombian Essential Oils against Different Candida Strains

Most Candida species are opportunistic pathogens with the ability to form biofilms, which increases their resistance to antifungal drug therapies and the host immune response. Essential oils (EOs) are an alternative for developing new antimicrobial drugs, due to their broad effect on cellular viability, cell communication, and metabolism. In this work, we evaluated the antifungal and antibiofilm potential of fifty EOs on C. albicans ATCC 10231, C. parapsilosis ATCC 22019, and Candida auris CDC B11903. The EOs’ antifungal activity was measured by means of a broth microdilution technique to determine the minimum inhibitory and fungicidal concentrations (MICs/MFCs) against the different Candida spp. strains. The effects on biofilm formation were determined by a crystal violet assay using 96-well round-bottom microplates incubated for 48 h at 35 °C. The EOs from Lippia alba (Verbenaceae family) carvone-limonene chemotype and L. origanoides exhibited the highest antifungal activity against C. auris. The L. origanoides EOs also presented antifungal and antibiofilm activity against all three Candida spp., thus representing a promising alternative for developing new antifungal products focused on yeast infections, especially those related to biofilm formation, virulence factors, and antimicrobial resistance.

Recent Developments in Polyphenol Applications on Human Health: A Review with Current Knowledge

Polyphenol has been used in treatment for some health disorders due to their diverse health promoting properties. These compounds can reduce the impacts of oxidation on the human body, prevent the organs and cell structure against deterioration and protect their functional integrity. The health promoting abilities are attributed to their high bioactivity imparting them high antioxidative, antihypertensive, immunomodulatory, antimicrobial, and antiviral activity, as well as anticancer properties. The application of polyphenols such as flavonoids, catechin, tannins, and phenolic acids in the food industry as bio-preservative substances for foods and beverages can exert a superb activity on the inhibition of oxidative stress via different types of mechanisms. In this review, the detailed classification of polyphenolic compunds and their important bioactivity with special focus on human health are addressed. Additionally, their ability to inhibit SARS-CoV-2 could be used as alternative therapy to treat COVID patients. Inclusions of polyphenolic compounds in various foods have demonstrated their ability to extend shelf life and they positive impacts on human health (antioxidative, antihypertensive, immunomodulatory, antimicrobial, anticancer). Additionally, their ability to inhibit the SARS-CoV-2 virus has been reported. Considering their natural occurrence and GRAS status they are highly recommended in food.

Synthesis of a new magnetic metal organic framework based on nickel for extraction of carvacrol and thymol in thymus and savory samples and analyzed with gas chromatography

The present research aims at reporting a new sorbent, a magnetic nano scale metal-organic framework (MOF), based on nickel acetate and 6-phenyl-1,3,5-triazine-2,4-diamine. The prepared sorbent was used to extract carvacrol and thymol using an ultrasonic-assisted dispersive micro solid phase extraction (UA-DμSPE) method. The structure of the metal organic framework was studied by applying scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectrometry (EDS), and vibrating sample magnetometer (VSM). The effects of various parameters such as ionic strength of sample solution, amount of sorbent (mg), volume of eluent solvent (μL), vortex and ultrasonic times (min) were optimized. Under optimal conditions, the analytes resulted in determination coefficients (R ²) of 0.9985 and 0.9967 in the concentration range 0.01-2 μg mL^-1, and in limits of detection of 0.0025 and 0.0028 μg mL^-1. Significantly, this method can be successfully applied in order to determine the target analytes in spiked real samples. Notably, the relative mean recoveries range from 94.5 to 105.7%.

Nanoemulsion-based approach to preserve muscle food: A review with current knowledge

Muscle foods are regarded as nutritionally dense foods while they are prone to spoilage by action of microorganism and oxidation. Recently, the consumer's preference is mostly toward minimally processed foods as well as preserved with natural preservatives. However, natural extract directly to the food matrix has several drawbacks. Hence development and applications of nanoemulsion has gained importance for the preservation of muscle foods to meet consumer requirements with enhanced food safety. Nanoemulsion utilizes natural extracts at much lower concentration with higher preservative abilities over original components. Nanoemulsions offer protection to the active component from degradation and ensure longer bioavailability. Novel techniques used for formulation of nanoemulsion provide stability to the emulsion with desirable qualities to improve their impacts. The application of nanoemulsion is known to enhance the preservative action of nanoemulsions by improving the microbial safety and oxidative stability in nanoform. This review provides recent updates on different methods used for formulation of nanoemulsions from different sources. Besides, successful application of nanoemulsion derived using natural agents for muscle food preservation and shelf life extension are reviewed. Thus, the application of nanoemulsion to extend shelf life and maintain quality is suggested for muscle foods.

Thymus Species from Romanian Spontaneous Flora as Promising Source of Phenolic Secondary Metabolites with Health-Related Benefits

Wild thyme aerial parts (Serpylli herba) are recognized as a valuable herbal product with antioxidant, anti-inflammatory, and antibacterial effects. Although pharmacopoeial regulations allow its collection exclusively from Thymus serpyllum, substitution with other species is frequent in current practice. This study analyzed the phenolic composition, antioxidant, and enzyme-inhibitory and antimicrobial activity of the hydroethanolic extracts obtained from five Romanian wild thyme species (Thymus alpestris, T. glabrescens, T. panonicus, T. pulcherimus and T. pulegioides). The analysis of individual phenolic constituents was performed through LC-ESI-DAD/MS², while for the in vitro evaluation of antioxidant potential, TEAC, FRAP, DPPH, TBARS and OxHLIA assays were employed. The anti-enzymatic potential was tested in vitro against tyrosinase, α-glucosidase and acetylcholinesterase. High rosmarinic acid contents were quantified in all species (20.06 ± 0.32-80.49 ± 0.001 mg/g dry extract); phenolic acids derivatives (including salvianolic acids) were confirmed as the principal metabolites of T. alpestris and T. glabrescens, while eriodictyol-O-di-hexoside was found exclusively in T. alpestris. All species showed strong antioxidant potential and moderate anti-enzymatic effect against α-glucosidase and acetylcholinesterase, showing no anti-tyrosinase activity. This is the first detailed report on the chemical and biological profile of T. alpestris collected from Romanian spontaneous flora.

Antibacterial Effect of 16 Essential Oils and Modulation of mex Efflux Pumps Gene Expression on Multidrug-Resistant Pseudomonas aeruginosa Clinical Isolates: Is Cinnamon a Good Fighter?

The purpose of the study was to describe the antimicrobial activity of 16 common essential oils (EOs) on multidrug-resistant (MDR) Pseudomonas aeruginosa clinical isolates, including the determination of the effects on mex efflux pumps gene expression. Seventy-two clinical isolates of P. aeruginosa collected between 2020-2022 were screened for susceptibility to EOs using Kirby-Bauer disk diffusion to identify potential candidates for future alternative therapies. The minimal inhibitory concentration (MIC) was further determined for the EO that proved antibacterial activity following the disk diffusion screening. Positive and negative controls were also used for method validation. Since cinnamon EO exhibited the best antimicrobial activity, it was further used to evaluate its influence on mex A, B, C, E, and X efflux pumps gene expression using real-time RT-PCR. Cinnamon EO inhibited all P. aeruginosa strains, followed by thyme EO (37.5%, n = 27) and lavender EO (12.5%, n = 9). The other EOs were less efficient. The MIC detection showed that cinnamon at a concentration of 0.05% v/v inhibited all MDR P. aeruginosa isolates. Thyme, turmeric, peppermint, basil, clove, and lavender EOs presented various results, most of them having activity at concentrations higher than 12.5% v/v. By studying the activity of cinnamon EO on mex efflux pumps, it was found that mexA and mexB (66.5%) were generally under-expressed. The remarkable results produced using the very low concentrations of cinnamon EO, with 100% antimicrobial activity against multi-, extended-, and pan- drug-resistant (MDR, XDR, PDR) P. aeruginosa clinical isolates, completed with the severe alteration of the RNA messaging system, supports its potential to be used as adjuvant treatment, with impact on therapeutic results.