Repellency, Fumigant Toxicity, Antifeedent and Residual Activities of Coridothymus capitatus and Its Main Component Carvacrol against Red Flour Beetle.

Tribolium castaneum is a challenging pest of stored products, causing significant economic losses. The present study explored the efficacy of Coridothymus capitatus essential oil and its primary constituent, carvacrol, as eco-friendly alternatives for managing this pest. To evaluate their insecticidal potential, repellency, fumigant toxicity, and antifeedant properties, progeny inhibition assays were performed. Carvacrol exhibited superior repellency compared to the essential oil, achieving a 92% repellency rate at 2 mg/cm2. Both compounds demonstrated significant fumigant toxicity against T. castaneum, with LC50 values of 168.47 and 106.5 µL/L for the essential oil and carvacrol, respectively, after 24 h. Carvacrol also outperformed the essential oil in antifeedant activity, inducing an 80.7% feeding deterrence at 1.17 mg/g. Moreover, both treatments effectively suppressed the development of the pest's progeny. These results collectively underscore the potent insecticidal properties of C. capitatus essential oil and carvacrol, particularly carvacrol, as promising candidates for the sustainable management of T. castaneum in stored product protection.

Gating elements for carvacrol activation of the OTOP1 proton channel.

Otopetrin 1 (OTOP1) is a proton-activated channel crucial for animals' perception of sour taste. Despite its significance, the gating mechanism of OTOP1 remains poorly understood. Here, we demonstrate that carvacrol activates the mouse OTOP1 (mOTOP1) channel under neutral and acidic conditions. Functional analysis showed that carvacrol enhances pH fluorescence signals in OTOP1-expressing cells, with reduced efficacy at lower pH levels. Carvacrol selectively activates mOTOP1, while mOTOP2, mOTOP3, and Chelonia mydas OTOP1 (CmOTOP1) are insensitive to carvacrol activation under neutral pH. Through chimera and point mutation experiments, swapping S134 in transmembrane segment 3 (TM3) and T247 in the TM5-6 linker abolished carvacrol activation of mOTOP1 and conferred activation on CmOTOP1, suggesting these two residues are critical for carvacrol sensitivity. These findings highlight TM3 and TM5-6 linker as pivotal gating apparatus of OTOP1 channels and potential docking sites for drug design.

Evaluation of antifungal and apoptotic effects of linalool, citral, and carvacrol separately and in combination with nystatin against clinical isolates of Pichia kudriavzevii.

Pichia kudriavzevii (formerly Candida krusei) poses a significant threat to immunocompromised patients due to its inherent resistance to various antifungal drugs. This study explored the anticandidal potential of citral, linalool, and carvacrol in combination with nystatin against P. kudriavzevii strains.Using the microdilution method following CLSI guidelines, Minimum Inhibitory Concentrations (MICs) and fungicidal concentrations (MFCs) were determined. Citral exhibited MIC values ranging from 50 to 100 µg/ml, averaging 70.24 ± 16.99 µg/ml, while carvacrol had MIC values of 50 to 100 µg/ml, averaging 86.90 ± 16.99 µg/ml. Linalool demonstrated weaker antifungal activity, with MIC values between 100 and 200 µg/ml, averaging 150 ± 38.73 µg/ml. The study assessed the synergistic effectsof these phenols with nystatin through fractional inhibitory concentration indices (FICIS). In addition, flow cytometry was employed to assess apoptosis induction in P. kudriavzevii cells.Carvacrol displayed a remarkable synergistic effect in combination with nystatin against all 21 isolates tested. Conversely, linalool showed synergy in 17 isolates, while citral exhibited synergy in only 2 isolates. These findings highlight distinct patterns of synergy between the different compounds and nystatin against P. kudriavzevii. Also, Carvacrol emerged as the most potent inducer of apoptosis across all P. kudriavzevii strains, followed by citral and linalool. This suggests that carvacrol not only possesses a stronger antifungal effect but also has a more pronounced ability to trigger programmed cell death in P. kudriavzevii. In conclusion, the study supports the potential of carvacrol, citral and linalool, as anticandidal agents, suggesting their supplementation with nystatin for treating P. kudriavzevii infections.

Inhibition of Cutaneous TRPV3 Channels by Natural Caffeic Acid for the Alleviation of Skin Inflammation.

Natural caffeic acid (CA) and its analogues have been studied for their potential applications in the treatment of various inflammatory and infectious skin diseases. However, the molecular mechanism underlying the effects of the CA remains largely unknown. Here, we report that CA and its two analogues, caffeic acid phenethyl ester (CAPE) and caffeic acid methyl caffeate (CAMC), inhibit TRPV3 currents in their concentration- and structure-dependent manners with IC50 values ranging from 102 to 410 µM. At the single-channel level, CA reduces the channel open probability and open frequency without alteration of unitary conductance. CA selectively inhibits TRPV3 relative to other subtypes of thermo-TRPs, such as TRPA1, TRPV1, TRPV4, and TRPM8. Molecular docking combined with site-specific mutagenesis reveals that a residue T636 in the Pore-loop is critical for CA binding to TRPV3. Further in vivo evaluation shows that CA significantly reverses TRPV3-mediated skin inflammation induced by skin sensitizer carvacrol. Altogether, our findings demonstrate that CA exerts its anti-inflammatory effects by selectively inhibiting TRPV3 through binding to the pocket formed by the Pore-loop and the S6. CA may serve as a lead for further modification and identification of specific TRPV3 channel inhibitors.

Antimicrobial cyclodextrin-assisted electrospun fibers loaded with carvacrol, citronellol and cinnamic acid for wound healing.

This work aimed to explore an alternative to the use of antibiotics for prevention and treatment of wounds infection caused by two common bacterial pathogens Staphylococcus aureus and Pseudomonas aeruginosa. For this purpose, three different essential oil components (EOCs), namely carvacrol, citronellol and cinnamic acid, were loaded into electrospun fibers of poly-ε-caprolactone (PCL) aided by alpha-cyclodextrin (αCD) and hydroxypropyl-ß-cyclodextrin (HPßCD). Electrospun-fibers prepared with each EOC and their mixtures were screened for antimicrobial capability and characterized regarding morphological, mechanical, thermal, surface polarity, antibiofilm and antioxidant properties. αCD formed poly(pseudo)rotaxanes with PCL and weakly interacted with EOCs, while HPßCD facilitated EOC encapsulation and formation of homogeneous fibers (500-1000 nm diameter) without beads. PCL/HPßCD fibers with high concentration of EOCs (mainly carvacrol and cinnamic acid) showed strong antibiofilm (>3 log CFU reduction) and antioxidant activity (10-50% DPPH scavenging effects). Different performances were recorded for the EOCs and their mixtures; cinnamic acid migrated to fiber surface and was released faster. Fibers biocompatibility was verified using hemolysis tests and in ovo tissue integration and angiogenesis assays. Overall, HPßCD facilitates complete release of EOCs from the fibers to the aqueous medium, being an environment-friendly and cost-effective strategy for the treatment of infected wounds.

Microfluidic-blow-spinning of carvacrol-loaded porphyrin metal - organic framework nanofiber films with synergistic antibacterial capabilities for food packaging.

The adherence of foodborne microorganisms threatens human health, necessitating the development of antibacterial food packaging films. In this study, the antibacterial agent carvacrol (CV), hindered by its high volatility and intense aromatic odor, was encapsulated within the photosensitive metal-organic frameworks (MOFs) material PCN-224 (loading rate 50%). Subsequently, the microfluidic-blow-spinning (MBS) technique was employed for the rapid fabrication of CV@PCN-224/polycaprolactone (PCL)/chitosan (CS) nanofiber films. The incorporation of CV@PCN-224 NPs enhances the nanofiber films' thermal stability and mechanical properties and improves the water vapor permeability while maintaining the sustained release of CV over an extended period and good biocompatibility. Due to the simultaneous loading of antibacterial agent (CV) and photosensitive agent (PCN-224), the CV@PCN-224/PCL/CS films exhibited good synergistic antibacterial functionality, as demonstrated by effective inhibition against both E. coli and S. aureus. All results show the vast potential of the prepared nanofiber films in antibacterial food packaging.

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.

Development of amphipathic derivatives of thymol and carvacrol as potent broad-spectrum antibacterial agents.

In the current study, to discover novel antibacterial agents, we designed and synthesized 72 carvacrol and thymol derivatives by biomimicking the structure and function of cationic antimicrobial peptides (AMPs). Many of the derivatives showed good antibacterial activity, and compound thy2I exhibited the most potent antibacterial activity with minimum inhibitory concentration (MIC) values ranging from 0.5 µg/mL to 8 µg/mL. Compound thy2I could kill both gram-positive and gram-negative bacteria via a membrane-targeting mechanism of action with a low frequency of resistance. In addition, thy2I had the advantages of good membrane selectivity, low toxicity in vitro and in vivo, and good plasma stability. The in vivo activity results revealed that thy2I exhibited a positive therapeutic effect in a mouse skin abscess model induced by Staphylococcus aureus ATCC29213. After thy2I treatment (10 mg/kg), the bacterial load of the S. aureus-infected abscesses was reduced by approximately 99.65 %. Our study suggests that thy2I may serve as an antibacterial lead for further clinical evaluation.

Solvent-Focused Gas Chromatographic Determination of Thymol and Carvacrol Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction through Solidifying Floating Organic Droplets (USA-DLLME-SFO).

An ultrasound-assisted dispersive liquid-liquid microextraction by solidifying floating organic droplets, coupled to a form of temperature-programmed gas chromatography flame ionization detection, has been developed for the extraction and determination of thymol and carvacrol. This method utilizes undecanol as the extraction solvent, offering advantages such as facilitating phase transfer through solidification and enhancing solvent-focusing efficiency. The optimal gas chromatography conditions include a sample injection volume of 0.2 µL, a split ratio of 1:10, and a flow rate of 0.7 mL min-1. The extraction conditions entail an extraction solvent volume of 20 µL, a disperser solvent (acetone) volume of 500 µL, pH 7.0, 7.0% NaCl (3.5 M), a sample volume of 5.0 mL, an ultrasound duration of 10 min, and a centrifuge time of 7.5 min (800 rpm). These conditions enable the achievement of a high and reasonable linear range of 3.5 to 70. 0 µg mL-1 for both thymol and carvacrol. The detection limits are found to be 0.95 and 0.89 µg mL-1, respectively, for thymol and carvacrol. The obtained relative standard deviations, 2.7% for thymol and 2.6% for carvacrol, demonstrate acceptable precision for the purpose of quantitative analysis.

Experimental and theoretical characterization of the release kinetic of carvacrol as inclusion complexes with ß-cyclodextrin in poly(lactic acid) and Mater-Bi® processed by supercritical impregnation.

The incorporation of active compounds into polymeric matrices using traditional methods has several drawbacks mainly due to the high volatility and thermal sensitivity of these substances. A solution to this problem could be the incorporation of bioactive compounds forming inclusion complexes as a strategy to improve the chemical stability, bioactivity and achieve controlled release. In this work, ß-cyclodextrin/carvacrol inclusion complex was prepared by spray drying to be incorporated into poly(lactic acid) (PLA) and Mater-Bi® films by supercritical CO2 impregnation. The impregnation process was carried out at pressures of 10, 15 and 20 MPa and at 40 °C. Both polymers showed the highest amount of incorporated inclusion complex at 15 MPa, where the percentage of impregnation varied from 0.6 % to 7.1 % in Mater-Bi® and PLA, respectively. Release tests for PLA films impregnated with inclusion complex showed a slow release of the active compound, which did not reach equilibrium after 350 h under the experimental conditions. This prolonged release was not observed in Mater-Bi® due to the lower incorporation of the inclusion complex. The release rate was described herein by a comprehensive phenomenological model considering the decomplexation kinetics combined with the equilibrium and mass transfer expressions.

Biofilm inhibition of denture cleaning tablets and carvacrol on denture bases produced with different techniques.

OBJECTIVES: This study compares the biofilm inhibition effects of denture cleaning tablets, carvacrol, and their combined use against Candida albicans on denture bases produced with different techniques. Additionally, the surface roughness and contact angles of these denture bases were evaluated. MATERIALS AND METHODS: Test samples were prepared from four different denture base materials (cold-polymerized, heat-polymerized, CAD/CAM milling, and 3D-printed). The surface roughness and contact angles of the test samples were measured using a profilometer and goniometer, respectively. For the evaluation of biofilm inhibition, samples were divided into 5 subgroups: Corega and carvacrol, separately and combined treatments, positive (inoculated with C. albicans) and negative control (non-inoculated with C. albicans, only medium). Biofilm mass was determined using the crystal violet method. An additional prepared test sample for each subgroup was examined under scanning electron microscopy (SEM). RESULTS: The surface roughness values of the 3D-printed test samples were found to be statistically higher than the other groups (P < .001). The water contact angle of all test materials was not statistically different from each other (P > .001). Corega and carvacrol, separately and combined, significantly decreased the amount of biofilm on all surfaces (P < .0001). Treatment of corega alone and in combination with carvacrol to the 3D-printed material caused less C. albicans inhibition than the other groups (P < .001; P < .05). CONCLUSIONS: The surface roughness values of all test groups were within the clinically acceptable threshold. Although Corega and carvacrol inhibited C. albicans biofilms, their combined use did not show a synergistic effect. CLINICAL RELEVANCE: Carvacrol may be used as one of the disinfectant agents for denture cleaning due to its biofilm inhibition property.

Carvacrol-loaded nanoemulsions stabilized by soy protein isolate / chitooligosaccharide conjugates inhibited the oxidation and conformational variations of myofibrillar proteins in refrigerated sea bass (Lateolabrax maculatus).

Soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The effects of CNE-SPI/COS on the oxidation and aggregation of myofibrillar protein (MPs) from sea bass (Lateolabrax maculatus) were investigated. Samples were immersed in sterile water (CK), SPI/COS solution and CNE-SPI/COS solution, respectively, follow by a 15-day refrigerated storage. MPs were extracted from fish fillets at 3-day intervals, then assessed for the oxidation degree and conformational changes in MPs, as well as structural variations in myofibrils. Compared with the CK group, the results obtained from protein oxidation assessment clarified that the oxidation and aggregation of MPs was significantly reduced by the CNE-SPI/COS treatment, as evidenced by the higher total sulfhydryl content and Ca2+-ATPase activity and lower surface hydrophobicity. Conformational analysis of MPs showed that CNE-SPI/COS was effective in maintaining the ordered secondary structure of MPs and reducing the exposure of hydrophobic residues in the hydrophobic core of the tertiary structure. In addition, CNE-SPI/COS was found to be effective in protecting the microstructure of muscle fibers and myofibrils in fish fillets. These results suggest that CNE-SPI/COS can be a promising method to prevent protein oxidation and aggregation in fish.

Fleagrass (Adenosma buchneroides Bonati) Acts as a Fungicide Against Candida albicans by Damaging Its Cell Wall.

Fleagrass, a herb known for its pleasant aroma, is widely used as a mosquito repellent, antibacterial agent, and for treating colds, reducing swelling, and alleviating pain. The antifungal effects of the essential oils of fleagrass and carvacrol against Candida albicans were investigated by evaluating the growth and the mycelial and biofilm development of C. albicans. Transmission electron microscopy was used to evaluate the integrity of the cell membrane and cell wall of C. albicans. Fleagrass exhibited high fungicidal activity against C. albicans at concentrations of 0.5% v/v (via the Ras1/cAMP/PKA pathway). Furthermore, transmission electron microscopy revealed damage to the cell wall and membrane after treatment with the essential oil, which was further confirmed by the increased levels of ß-1,3-glucan and chitin in the cell wall. This study showed that fleagrass exerts good fungicidal and hyphal growth inhibition activity against C. albicans by disrupting its cell wall, and thus, fleagrass may be a potential antifungal drug.

Carvacrol alleviates CUMS-induced depressive-like behaviors and cognitive impairment by reducing oxidative stress and neuroinflammation in mice.

The present study aimed to evaluate the protective potential of carvacrol against depressive-like behavior and cognitive impairment prompted by chronic unpredictable mild stress (CUMS) in mice. The animals were divided into six groups: Control (non-stressed), CARV (carvacrol at 50 mg/kg, p.o.), FLU (fluoxetine at 10 mg/kg, p.o.), CUMS (stressed), CUMS + CARV and CUMS + FLU, and the groups with CUMS were subjected to different stressors for 28 days. After treatment, mice underwent behavioral testing (open field, forced swimming, sucrose preference, social interaction, novel object recognition and Y-maze) and brain areas were removed for oxidative stress (MDA, nitrite/nitrate and GSH levels) and cytokine (IL-1ß and TNF-α) content assays. The results revealed that CARV administration reversed depressive-like behavior and significantly ameliorated the cognitive deficit induced by CUMS, as well as was able to attenuate oxidative stress (decreased MDA and nitrite/nitrate levels and increased GSH levels). In addition, a significant reduction in hippocampal IL-1ß and TNF-α levels was observed, demonstrating a potential anti-neuroinflammatory activity. Taken together, the antioxidant and anti-inflammatory activities observed in this study indicate that CARV is a promising drug for antidepressant treatment.

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.

Evaluation of Different Drying Treatments with Respect to Essential Oil Components, Phenolic and Flavonoid Compounds, and Antioxidant Capacity of Ajowan (Trachyspermum ammi L.).

Ajowan (Trachyspermum ammi L.) is considered a valuable spice and medicinal herb. In this study, the essential oil content and composition of the aerial parts of ajowan were investigated under different drying treatments (sun, shade, oven at 45 °C, oven at 65 °C, microwave, and freeze drying). Moreover, the phenolic content, flavonoid content, and antioxidant capacity of samples were also assessed. Fresh samples produced the highest essential oil content (1.05%), followed by those treated under sun (0.7%) and shade drying (0.95%). Based on gas chromatography-mass spectrometry (GC-MS), thirty compounds were determined in which thymol (34.84-83.1%), carvacrol (0.15-32.36%), p-cymene (0.09-13.66%), and γ-terpinene (3.12-22.58%) were the most abundant. Among the drying methods, freeze drying revealed the highest thymol content, followed by drying in a 45 °C oven. The highest TPC (total phenolic content) and TFC (total flavonoid content) were obtained in the fresh sample (38.23 mg TAE g-1 dry weight (DW)) and in the sample oven-dried at 45 °C (7.3 mg QE g-1 DW), respectively. Based on the HPLC results, caffeic acid (18.04-21.32 mg/100 gDW) and ferulic acid (13.102-19.436 mg/100 g DW) were the most abundant phenolic acids, while among flavonoids, rutin constituted the highest amount (10.26-19.88 mg/100 gDW). Overall, freeze drying was the most promising method of drying for preserving the phenolic (TPC) and flavonoid (TFC) compounds and oil components.

A carrier-free, injectable, and self-assembling hydrogel based on carvacrol and glycyrrhizin exhibits high antibacterial activity and enhances healing of MRSA-infected wounds.

Inspired by glycyrrhizin's strong pharmacological activities and the directed self-assembly into hydrogels, we created a novel carrier-free, injectable hydrogel (CAR@glycygel) by combining glycyrrhizin with carvacrol (CAR), without any other chemical crosslinkers, to promote wound healing on bacteria-infected skin. CAR appeared to readily dissolve and load into CAR@glycygel. CAR@glycygel had a dense, porous, sponge structure and strong antioxidant characteristics. In vitro, it showed better antibacterial ability than free CAR. For methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, and Escherichia coli, the diameter of inhibition zone values of CAR@glycygel were 3.80 ± 0.04, 3.31 ± 0.20 and 3.12 ± 0.24 times greater, respectively, than those of free CAR. The MICs for CAR@glycygel was 156.25 µg/mL while it was 1250.00 µg/mL for free CAR to these three bacteria. Its antibacterial mechanism appeared to involve destruction of the integrity of the bacterial cell wall and biomembrane, leading to a leakage of AKP and inhibition of biofilm formation. In vivo, CAR@glycygel effectively stopped bleeding. When applied to skin wounds on rats infected with MRSA, CAR@glycygel had strong bactericidal activity and improved wound healing. The wound healing rates for CAR@glycygel were 49.59 ± 15.78 %, 93.02 ± 3.09 % and 99.02 ± 0.55 % on day 3, day 7, and day 11, respectively, which were much better than blank control and positive control groups. Mechanisms of CAR@glycygel accelerating wound healing involved facilitating epidermis remolding, promoting the growth of hair follicles, stimulating collagen deposition, mitigating inflammation, and promoting angiogenesis. Overall, CAR@glycygel showed great potential as wound dressing for infected skin wounds.

Study of the Resistance of Staphylococcus aureus Biofilm, Biofilm-Detached Cells, and Planktonic Cells to Microencapsulated Carvacrol Used Alone or Combined with Low-pH Treatment.

Microbial biofilms pose severe problems in the medical field and food industry, as they are the cause of many serious infections and food-borne diseases. The extreme biofilms' resistance to conventional anti-microbial treatments presents a major challenge to their elimination. In this study, the difference in resistance between Staphylococcus aureus DSMZ 12463 biofilms, biofilm-detached cells, and planktonic cells against microcapsules containing carvacrol was assessed. The antimicrobial/antibiofilm activity of low pH disinfection medium containing the microencapsulated carvacrol was also studied. In addition, the effect of low pH on the in vitro carvacrol release from microcapsules was investigated. The minimum inhibitory concentration of microencapsulated carvacrol was 0.625 mg mL-1. The results showed that biofilms exhibited greater resistance to microencapsulated carvacrol than the biofilm-detached cells and planktonic cells. Low pH treatment alone, by hydrochloric acid addition, showed no bactericidal effect on any of the three states of S. aureus strain. However, microencapsulated carvacrol was able to significantly reduce the planktonic cells and biofilm-detached cells below the detection limit (no bacterial counts), and the biofilm by approximatively 3 log CFU mL-1. In addition, results showed that microencapsulated carvacrol combined with low pH treatment reduced biofilm by more than 5 log CFU mL-1. Thus, the use of microencapsulated carvacrol in acidic environment could be a promising approach to combat biofilms from abiotic surfaces.

Surface-Charge Tuned Polymeric Nanoemulsions for Carvacrol Delivery in Interkingdom Biofilms.

Biofilms, intricate microbial communities entrenched in extracellular polymeric substance (EPS) matrices, pose formidable challenges in infectious disease treatment, especially in the context of interkingdom biofilms prevalent in the oral environment. This study investigates the potential of carvacrol-loaded biodegradable nanoemulsions (NEs) with systematically varied surface charges─cationic guanidinium (GMT-NE) and anionic carboxylate (CMT-NE). Zeta potentials of +25 mV (GMT-NE) and -33 mV (CMT-NE) underscore successful nanoemulsion fabrication (∼250 nm). Fluorescent labeling and dynamic tracking across three dimensions expose GMT-NE's superior diffusion into oral biofilms, yielding a robust antimicrobial effect with 99.99% killing for both streptococcal and Candida species and marked reductions in bacterial cell viability compared to CMT-NE (∼4-log reduction). Oral mucosa tissue cultures affirm the biocompatibility of both NEs with no morphological or structural changes, showcasing their potential for combating intractable biofilm infections in oral environment. This study advances our understanding of NE surface charges and their interactions within interkingdom biofilms, providing insights crucial for addressing complex infections involving bacteria and fungi in the demanding oral context.

Citrus oil gland and cuticular wax inspired multifunctional gelatin film of OSA-starch nanoparticles-based nanoemulsions for preserving perishable fruit.

Inspired by the citrus oil gland and cuticular wax, a multifunctional material that stably and continuously released the carvacrol and provided physical defenses was developed to address issues of fresh-cut fruits to microbial infestation and moisture loss. The results confirmed that low molecular weight and loose structure of starch nanoparticles prepared by the ultrasound-assisted Fenton system were preferable for octenyl succinic anhydride modification compared to native starch, achieving a higher degree of substitution (increased by 18.59 %), utilizing in preparing nanoemulsions (NEs) for encapsulating carvacrol (at 5 % level: 81.58 %). Furthermore, the NEs-based gelatin (G) film improved with surface hydrophobic modification by myristic acid (MA) successfully replicated the citrus oil gland and cuticular wax, providing superior antioxidant (enhanced by 3-4 times) and antimicrobial properties (95.99 % and 84.97 % against Staphylococcus aureus and Escherichia coli respectively), as well as the exceptional UV shielding (nearly 0 transmittance in the UV region), mechanical (72 % increase in tensile strength), and hydrophobic (WCA 133.63°). Moreover, the 5%NE-G@MA film inhibited foodborne microbial growth (reduced by 50 %) and water loss (controlled below 15 %), extending the shelf life of fresh-cut navel orange and kiwi. Thus, the multifunctional film was a potential shield for preserving perishable fresh-cut products.