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.

A nanozyme with switchable enzyme-like activity for the logic gates detection of thymol and hydrogen peroxide in honey.

A new nanozyme (CuGaa) with switchable enzyme-like activity of peroxidase and polyphenol oxidase was successfully prepared based on guanidinoacetic acid and copper. The two enzyme-like activities can be easily switched by changing temperature or adding MnCl2. At 4 °C, polyphenol oxidase-like activity decreased to nearly 1%, and the material is mainly characterized by peroxidase-like activity at this point. However, at 60 °C in the presence of 20 mM MnCl2, the peroxidase-like activity decreased to nearly 10%, and the polyphenol oxidase-like activity of the materials increased to 140%. Based on the switchable enzyme-like activity of CuGaa, detection methods for thymol and hydrogen peroxide were developed. In addition, a rapid combination strategy was further established combined with logic gate technology for the facile identification of complex contamination in honey, which provided new ideas for low-cost and rapid honey identification.

Inhibitory Effects of Endemic Thyme's Thymol-Carvacrol Chemotype Essential Oil on Aspergillus Species with Free Radical Scavenging Properties.

There is a burgeoning focus on utilizing the antifungal and antioxidant properties of essential oils derived from various plants as a modern and natural approach to combat the growth of fungi that contaminate food. In this study, we used essential oils extracted from Thymus daenensis Celak. subsp. daenensis to address three mycotoxin-producing species of Aspergillus, specifically A. flavus, A. parasiticus, and A. niger, all of which are recognized contaminants of food and agricultural products. Concurrently, the antioxidant properties of the essential oils were evaluated, revealing their noteworthy role in the antifungal activity. Essential oils were derived from T. daenensis subsp. daenensis was observed to have a significant inhibitory effect on all three species of Aspergillus, as evidenced by the minimum inhibitory concentration (MIC) ranging from 575 to 707 ppm and the half-maximal inhibitory concentration (IC50) ranging from 237 to 280 ppm. These results confirm the strong antifungal activity of the essential oils. Furthermore, the essential oil exhibited free radical scavenging activity, resulting in an EC50 value of 37.1 µg/ml. In summary, T. daenensis subsp. daenensis essential oil demonstrated a competitive advantage over other similar plants and synthetic antibiotics. This indicates the promising potential of this essential oil as a natural antifungal agent to control Aspergillus growth and mycotoxin contamination. It offers an alternative or complementary approach to conventional antifungal agents and could be a valuable addition to the arsenal of natural remedies to address fungal contamination in food and agricultural products.

Phytochemical analysis and biological activities of essential oils extracted from Origanum grossii and Thymus pallidus: in vitro and in silico analysis.

The study aimed at investigating the phytochemical composition, antioxidant and antibacterial activities of essential oils (EOs) of Origanum grossii and Thymus pallidus. The selection of these plants for the study was driven by a comprehensive survey conducted in the Ribat Elkheir region of Morocco, where these plants are widely utilized. The results reflect the valorization of these plants based on the findings of the regional survey. The GC-MS phytochemical analysis revealed that the main constituents of the essential oil were carvacrol and thymol for O. grossii and T. pallidus respectively. Quantitative assays demonstrated that O. grossii exhibited higher levels of polyphenols (0.136 mg AGE/mg EO) and flavonoids (0.207 mg QE/mg EO) compared to T. pallidus. The DPPH assay indicated that O. grossii EOs possessed approximately twice the antiradical activity of T. pallidus, with IC50 values of approximately 0.073 mg/mL and 0.131 mg/mL, respectively. The antibacterial activity tests showed that both essential oils exhibited significant inhibition zones ranging from 26 to 42 mm against all tested bacterial strains. The MIC values varied among the bacteria, generally falling within the range of 0.31 to 2.44 µg/mL, demonstrating the potency of the EOs to serve as antibacterial. Molecular docking revealed that O. grossii and T. pallidus essential oils interact with antibacterial and antioxidant proteins (1AJ6 and 6QME). Key compounds in O. grossii include p-cymene, eucalyptol, and carvacrol, while T. pallidus contains potent chemicals like p-cymene, ɤ-maaliene, valencene, α-terpinene, caryophyllene, himachalene, and thymol. Notably, the most potent chemicals in Origanum grossii are p-cymene, eucalyptol, and carvacrol, while the most potent chemicals in Thymus pallidus are p-cymene, α-terpinene, and thymol. These findings suggest that these plant EOs could be used to develop new natural products with antibacterial and antioxidant activity.

Separation and Qualitative Study of Mentha asiatica Boriss. Essential Oil Components by prep-GC, GC-QTOF-MS, NMR and Prediction of Bioactive Compounds.

In order to understand the material basis of wild Mentha asiatica Boris. in Xinjiang, the chemical constituents of essential oil extracted from aerial parts of this plant were studied. A total 52 components were detected and 45 compounds were identified. First of all, the essential oil was separated by silica gel column chromatography, and divided into several parts according to the results of thin layer chromatography. Eight fractions were obtained, and then each fragment was preliminarily screened for antibacterial activity. It was found that all eight fragments had certain antibacterial activity in different level. Then the fractions were subjected to preparative gas chromatography (prep-GC) for further isolation. Ten compounds were identified by 13 C-NMR, 1 H-NMR and gas chromatography-quadrupole time of flight-Mass spectrometry (GC-QTOF-MS). They are sabinene, limonene and ß-caryophyllene, (1R*,3S*,5R*)-sabinyl acetate, piperitone oxide, rotundifolone, thymol, piperitone, 4-hydroxypiperiditone, cedrol. After screened by bioautography, 4-hydroxypiperone and thymol were showed best antibacterial activity. The inhibitory effects of the two isolated compounds on Candida albicans and their related mechanisms were studied. The results showed that, 4-hydroxypiperone and thymol significantly reduced ergosterol content on the surface of Candida albicans cell membrane in a dose-dependent manner. This work has accumulated experience for the development and utilization of Xinjiang characteristic medicinal plant resources and new drug research and development, and provided scientific basis and support for the later research and development of Mentha asiatica Boris.

In vitro antitrichomonal activity of Satureja khuzestanica and main essential oil components carvacrol, thymol, and eugenol.

INTRODUCTION: Human trichomoniasis is a widespread sexually transmitted disease and the concern of drug resistance in the parasite is growing. Hence, this study was performed to evaluate in vitro antitrichomonal activity of Satureja khuzestanica, carvacrol, thymol, eugenol, and phytochemical evaluation of the S. khuzestanica oil. METHODOLOGY: Extracts and essential oil of S. khuzestanica, and the components were prepared. Then, susceptibility testing was performed using the microtiter plate method and Trichomonas vaginalis isolates. The minimum lethal concentration (MLC) of the agents was determined in comparison with metronidazole. Also, the essential oil was investigated by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector. RESULTS: After 48 hours of incubation, carvacrol and thymol were the most effective antitrichomonal agents with MLC of 100 µg/mL, followed by the essential oil and hexanic extract (MLC = 200 µg/mL), then eugenol and methanolic extract (MLC = 400 µg/mL), in comparison with the metronidazole MLC of 6.8 µg/mL. Overall, 33 identified compounds accounted for 98.72% of the total essential oil composition with carvacrol, thymol, and p-cymene being the major constituents. CONCLUSIONS: The results suggested the potency of S. khuzestanica and its bioactive ingredients against T. vaginalis. Thus, further in vivo studies are required to evaluate the efficacies of the agents.

A comparative study on DNA and protein binding properties of thymol and thymoquinone.

Two phytochemicals, thymol and thymoquinone obtained from thymes (Thymus vulgaris L., Lamiaceae etc.) and Nagila Sativa seed, respectively. Both the phytochemicals show several biochemical activities like anticancer, antimicrobial etc. In this paper, we studied the affinities of thymol and thymoquinone towards calf thymus DNA (CT-DNA) and protein (bovine serum albumin). Spectroscopic and molecular modelling studies revealed that both compounds have a high affinity toward both the receptors; DNA and protein. Both phytochemicals binds to the minor grooves of DNA and suitable pockets of protein. Several free energy function and hydrogen bonding play significant role during the binding phenomenon.Communicated by Ramaswamy H. Sarma.

Thymol-Based Hydrophobic Deep Eutectic Solvents as a Green Approach for Screening Polar Nitrosamines in Sartans Pharmaceutical Products by Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with HPLC-DAD.

Nitrosamines are carcinogens substances firstly detected in sartans drugs in 2018, leading to new regulations and monitoring programmes that raised the costs and challenges to the pharmaceutical industry. Therefore, reliable and cost-effective methods for screening nitrosamines in medicines are highly desirable. Hydrophobic deep eutectic solvents (HDES), a novel "eco-friendly" alternative to solvents commonly used in microextraction techniques, can meet these requirements. In this study, a simple and rapid method of ultrasound-assisted dispersive liquid-liquid microextraction using thymol-based HDES followed by HPLC-DAD detection was developed for the determination of n-nitrosodimethylamine (NDMA) and n-nitroso-n-methylamino butyric acid (NMBA) from candesartan, irbesartan, losartan, olmesartan, telmisartan and valsartan drug substances, and from losartan tablets. Various influencing factors (such as HDES type, HDES:sample ratio, salt addition and sample pH) were investigated. Best extraction efficiencies were achieved with thymol:benzyl alcohol HDES. Under optimal conditions, the linearities ranged from 15 to 1000 ng mL-1 for both NDMA and NMBA (R² > 0.99), with recoveries between 81.8-104.2% and precision from 0.2 to 14.6%. The limits of detection were 17.3 - 220.0 ng g-1 and 16.3 - 290.0 ng g-1 for NDMA and NMBA, consecutively. Finally, the proposed method was successfully applied in spiked sartans drug substances and in losartan potassium tablets collected in the market.

Can Origanum be a hope for cancer treatment? A review on the potential of Origanum species in preventing and treating cancers.

In this study, the potential of aromatic Origanum species belonging to Lamiaceae family to prevent and treat cancer was investigated. Since aromatic plants contain phytochemicals such as essential oils, phenolic acids, terpenoids, flavonoids, alkaloids, vitamins, enzymes and minerals with beneficial biological activities, they have become more interesting and important in medicine, pharmacy and industry. Publications/research between 1950 and 2022 were screened to investigate the effects of Origanum species on cancer, and the effects of their extracts and essential oils in cancer prevention and treatment. Essential phytochemicals found in plants provide efficacy in the prevention and treatment of many diseases. Besides, the essential oils found in these plant extracts are another reason that makes them important. Therefore, it is preferred in traditional medicine in the fight against many diseases as well as cancer. Essential oils of Origanum species mainly contain monoterpenes such as p-cymene, carvacrol, thymol and γ-terpinene. Since these compounds exhibit anticancer properties, Origanum species are becoming the plants of choice in the fight against cancer. In this context, Origanum majorana L. Origanum vulgare and Origanum munzurense are promising species, considering the composition of their extracts and essential oil.

Comparison of Origanum Essential Oil Chemical Compounds and Their Antibacterial Activity against Cronobacter sakazakii.

Origanum vulgare L. (oregano) is an aromatic plant with wide applications in the food and pharmaceutical industries. Cronobacter sakazakii, which has a high detection rate in powdered infant formula, adversely impacts susceptible individuals. Oregano essential oil (OEO) is a natural antibacterial agent that can be used to fight bacterial contamination. Here, OEO chemical compounds from eight oregano varieties were analyzed by gas chromatography-mass spectrometry and their antibacterial properties were assessed. The eight OEOs were clustered into two groups and were more diverse in group 2 than in group 1. Six compounds, including p-cymene, 3-thujene, γ-terpinene, thymol, carvacrol, and caryophyllene, were shared by eight OEOs. Among the eight oregano varieties, OEOs from O. vulgare sc2 had the strongest antibacterial activity against C. sakazaki, with the inhibition zone of 18.22mm. OEOs from O. vulgare jx, O. 'Nvying', O. vulgare 'Ehuang', and O. vulgare ssp. virens were also potent. Moreover, the antibacterial activity of OEOs was positively correlated with the relative content of thymol. As the main OEO antibacterial compound, thymol affected the normal growth and metabolism of C. sakazakii cells by destroying the bacterial membrane and decreasing the intracellular ATP concentration. Thus, in light of the antibacterial activity detected in the OEOs from the eight oregano varieties, this study provides a theoretical foundation for oregano cultivar management and development.

In Silico Evaluation of the Antimicrobial Activity of Thymol-Major Compounds in the Essential Oil of Lippia thymoides Mart. & Schauer (Verbenaceae).

In this paper, we evaluated the drug-receptor interactions responsible for the antimicrobial activity of thymol, the major compound present in the essential oil (EO) of Lippia thymoides (L. thymoides) Mart. & Schauer (Verbenaceae). It was previously reported that this EO exhibits antimicrobial activity against Candida albicans (C. albicans), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli). Therefore, we used molecular docking, molecular dynamics simulations, and free energy calculations to investigate the interaction of thymol with pharmacological receptors of interest to combat these pathogens. We found that thymol interacted favorably with the active sites of the microorganisms' molecular targets. MolDock Score results for systems formed with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli) were -77.85, -67.53, and -60.88, respectively. Throughout the duration of the MD simulations, thymol continued interacting with the binding pocket of the molecular target of each microorganism. The van der Waals (ΔEvdW = -24.88, -26.44, -21.71 kcal/mol, respectively) and electrostatic interaction energies (ΔEele = -3.94, -11.07, -12.43 kcal/mol, respectively) and the nonpolar solvation energies (ΔGNP = -3.37, -3.25, -2.93 kcal/mol, respectively) were mainly responsible for the formation of complexes with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli).

Newly Synthesized Thymol Derivative and Its Effect on Colorectal Cancer Cells.

Thymol affects various types of tumor cell lines, including colorectal cancer cells. However, the hydrophobic properties of thymol prevent its wider use. Therefore, new derivatives (acetic acid thymol ester, thymol ß-D-glucoside) have been synthesized with respect to hydrophilic properties. The cytotoxic effect of the new derivatives on the colorectal cancer cell lines HT-29 and HCT-116 was assessed via MTT assay. The genotoxic effect was determined by comet assay and micronucleus analysis. ROS production was evaluated using ROS-Glo™ H2O2 Assay. We confirmed that one of the thymol derivatives (acetic acid thymol ester) has the potential to have a cyto/genotoxic effect on colorectal cancer cells, even at much lower (IC50~0.08 µg/mL) concentrations than standard thymol (IC50~60 µg/mL) after 24 h of treatment. On the other side, the genotoxic effect of the second studied derivative-thymol ß-D-glucoside was observed at a concentration of about 1000 µg/mL. The antiproliferative effect of studied derivatives of thymol on the colorectal cancer cell lines was found to be both dose- and time-dependent at 100 h. Moreover, thymol derivative-treated cells did not show any significantly increased rate of micronuclei formation. New derivatives of thymol significantly increased ROS production too. The results confirmed that the effect of the derivative on tumor cells depends on its chemical structure, but further detailed research is needed. However, thymol and its derivatives have great potential in the prevention and treatment of colorectal cancer, which remains one of the most common cancers in the world.

Impact of drying methods on the yield and chemistry of Origanum vulgare L. essential oil.

Oregano (Origanum vulgare L.) is mainly cultivated, both as fresh and dried herb, for several purposes, such as ailments, drugs, and spices. To evaluate the influence of some drying methods on the chemical composition of the essential oil of oregano, its aerial parts were dehydrated by convective drying techniques (shade, static oven), microwave-assisted heating (three different treatments) and osmotic treatment. The oils were analyzed by GC-FID and GC-MS. The highest essential oil yield was achieved from microwave and shade drying methods. In total, 39 components were found, with carvacrol (ranging from 56.2 to 81.4%) being the main constituent; other compounds present in lower amounts were p-cymene (1.6-17.7%), γ-terpinene (0.8-14.2%), α-pinene (0.1-2.1%), thymol methyl ether (0.4-1.8%) and thimoquinone (0.5-3.5%). The essential oil yields varied among the different treatments as well as the relative compositions. The percentages of p-cymene, γ-terpinene and α-pinene decreased significantly in the dried sample compared with the fresh sample; on the other hand, carvacrol, isoborneol and linalool increased significantly in the dried materials. The choice of the drying method for obtaining the essential oil therefore appears crucial not only in relation to the higher yield but also and above all in reference to the percentage presence of components that can direct the essential oil toward an appropriate use.

Performance of Thyme Oil@Na-Montmorillonite and Thyme Oil@Organo-Modified Montmorillonite Nanostructures on the Development of Melt-Extruded Poly-L-lactic Acid Antioxidant Active Packaging Films.

Today, the use of natural biodegradable materials in the production processes is more and more adopted by industry to achieve cyclic economy targets and to improve environmental and human health indexes. Active packaging is the latest trend for food preservation. In this work, nanostructures were prepared by incorporation of thyme oil with natural natrium-montmorillonite and organo-montmorillonite with two different techniques, direct impregnation and the green evaporation-adsorption process. Such nanostructures were mixed with poly-L-lactic-acid for the first time via an extrusion molding process to develop a new packaging film. Comparisons of morphological, mechanical, and other basic properties for food packaging were carried out via XRD, FTIR, TG, SEM/EDS, oxygen and water vapor permeation, and antimicrobial and antioxidant activity for the first time. Results showed that poly-L-lactic-acid could be modified with clays and essential oils to produce improved active packaging films. The final product exhibits food odor prevention characteristics and shelf-life extension capabilities, and it could be used for active packaging. The films based on OrgMt clay seems to be more promising, while the thyme oil addition improves their behavior as active packaging. The PLLA/3%TO@OrgMt and PLLA/5%TO@OrgMt films were qualified between the tested samples as the most promising materials for this purpose.

Chitosan based encapsulation increased the apoptotic efficacy of thymol on A549 cells and exhibited non toxic response in swiss albino mice.

Thymol is a plant-derived natural phenolic compound abundantly present in Thymus vulgaris species. In the present study, we developed a chitosan-based drug delivery system to deliver thymol to A549 cells. The physicochemical properties of thymol-loaded chitosan nanoparticles (thymol-NP) were characterized using polyphasic techniques viz., FTIR, XRD, DLS, and SEM. Thymol-NP exhibited a size of 282.5 nm and encapsulation efficiency of 74.08 ± 0.73%. The IC50 of thymol-NP against A549 cells was 99.57 µg/ml at 24 h, which was lower than that of the pure form. Clear apoptotic features such as cellular morphology, cell shrinkage, and augmentation of dead cells were observed in both the thymol and thymol-NP treated A549 cells. The percentage of apoptotic cells in the thymol-NP IC50 treated cells was >90% which was considerably higher than the group treated with thymol alone. In vivo toxicity study showed that the swiss albino mice treated up to a concentration of 1000 mg/kg of thymol-NP neither showed signs of toxicity nor death up to 14 days. Also, no significant influence was observed on behavior, body weight, organ weight, and organ histology. Overall, the data concluded that thymol-NP can be considered a safe and potent drug candidate against A549 cells.

In vitro toxicological evaluation of mesoporous silica microparticles functionalised with carvacrol and thymol.

The cytotoxicity of carvacrol- and thymol-functionalised mesoporous silica microparticles (MCM-41) was assessed in the human hepatocarcinoma cell line (HepG2). Cell viability, lactate dehydrogenase (LDH) activity, reactive oxygen species (ROS) production, mitochondrial membrane potential (ΔΨm), lipid peroxidation (LPO) and apoptosis/necrosis analyses were used as endpoints. The results showed that both materials induced cytotoxicity in a time- and concentration-dependent manner, and were more cytotoxic than free essential oil components and bare MCM-41. This effect was caused by cell-particle interactions and not by degradation products released to the culture media, as demonstrated in the extract dilution assays. LDH release was a less sensitive endpoint than the MTT (thiazolyl blue tetrazolium bromide) assay, which suggests the impairment of the mitochondrial function as the primary cytotoxic mechanism. In vitro tests on specialised cell functions showed that exposure to sublethal concentrations of these materials did not induce ROS formation during 2 h of exposure, but produced LPO and ΔΨm alterations in a concentration-dependent manner when cells were exposed for 24 h. The obtained results generally support the hypothesis that the carvacrol- and thymol-functionalised MCM-41 microparticles induced toxicity in HepG2 cells by an oxidative stress-related mechanism that resulted in apoptosis through the mitochondrial pathway.

The biosynthesis of thymol, carvacrol, and thymohydroquinone in Lamiaceae proceeds via cytochrome P450s and a short-chain dehydrogenase.

Thymol and carvacrol are phenolic monoterpenes found in thyme, oregano, and several other species of the Lamiaceae. Long valued for their smell and taste, these substances also have antibacterial and anti-spasmolytic properties. They are also suggested to be precursors of thymohydroquinone and thymoquinone, monoterpenes with anti-inflammatory, antioxidant, and antitumor activities. Thymol and carvacrol biosynthesis has been proposed to proceed by the cyclization of geranyl diphosphate to γ-terpinene, followed by a series of oxidations via p-cymene. Here, we show that γ-terpinene is oxidized by cytochrome P450 monooxygenases (P450s) of the CYP71D subfamily to produce unstable cyclohexadienol intermediates, which are then dehydrogenated by a short-chain dehydrogenase/reductase (SDR) to the corresponding ketones. The subsequent formation of the aromatic compounds occurs via keto-enol tautomerisms. Combining these enzymes with γ-terpinene in in vitro assays or in vivo in Nicotiana benthamiana yielded thymol and carvacrol as products. In the absence of the SDRs, only p-cymene was formed by rearrangement of the cyclohexadienol intermediates. The nature of these unstable intermediates was inferred from reactions with the γ-terpinene isomer limonene and by analogy to reactions catalyzed by related enzymes. We also identified and characterized two P450s of the CYP76S and CYP736A subfamilies that catalyze the hydroxylation of thymol and carvacrol to thymohydroquinone when heterologously expressed in yeast and N. benthamiana Our findings alter previous views of thymol and carvacrol formation, identify the enzymes involved in the biosynthesis of these phenolic monoterpenes and thymohydroquinone in the Lamiaceae, and provide targets for metabolic engineering of high-value terpenes in plants.

Release of Cinnamaldehyde and Thymol from PLA/Tilapia Fish Gelatin-Sodium Alginate Bilayer Films to Liquid and Solid Food Simulants, and Japanese Sea Bass: A Comparative Study.

This study aimed to develop an active biodegradable bilayer film and to investigate the release behaviors of active compounds into different food matrices. Cinnamaldehyde (CI) or thymol (Ty) was encapsulated in ß-cyclodextrin (ß-CD) to prepare the active ß-CD inclusion complex (ß-CD-CI/ß-CD-Ty). The tilapia fish gelatin-sodium alginate composite (FGSA) containing ß-CD-CI or ß-CD-Ty was coated on the surface of PLA film to obtain the active bilayer film. Different food simulants including liquid food simulants (water, 3% acetic acid, 10% ethanol, and 95% ethanol), solid dry food simulant (modified polyphenylene oxide (Tenax TA)), and the real food (Japanese sea bass) were selected to investigate the release behaviors of bilayer films into different food matrixes. The results showed that the prepared ß-CD inclusion complexes distributed evenly in the cross-linking structure of FGSA and improved the thickness and water contact angle of the bilayer films. Active compounds possessed the lowest release rates in Tenax TA, compared to the release to liquid simulants and sea bass. CI and Ty sustained the release to the sea bass matrix with a similar behavior to the release to 95% ethanol. The bilayer film containing ß-CD-Ty exhibited stronger active antibacterial and antioxidant activities, probably due to the higher release efficiency of Ty in test mediums.

Comparison of Aging Resistance and Antimicrobial Properties of Ethylene-Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum).

The effects of plant-based extracts on the solar aging and antimicrobial properties of impregnated ethylene-norbornene (EN) copolymer and poly(lactic acid) (PLA) were investigated. In this study, the impregnation yield of polyolefin, lacking in active centers capable of phytochemical bonding, and polyester, abundant in active sides, was measured. Moreover, two different extracts plentiful in phytochemicals-thyme (TE) and clove (CE)-were employed in the solvent-based impregnation process. The effect of thymol and eugenol, the two main compounds embodied in the extracts, was studied as well. Interestingly, oxidation induction times (OIT) for the impregnation of EN with thyme and clove extracts were established to be, respectively, 27.7 and 39.02 min, which are higher than for thymol (18.4 min) and eugenol (21.1 min). Therefore, an aging experiment, mimicking the full spectrum of sunlight, was carried out to investigate the resistance to common radiation of materials impregnated with antioxidative substances. As expected, the experiment revealed that the natural extracts increased the shelf-life of the polymer matrix by inhibiting the degradation processes. The aging resistance was assessed based on detected changes in the materials' behavior and structure that were examined with Fourier-transform infrared spectroscopy, contact angle measurements, color quantification, tensile tests, and hardness investigation. Such broad results of solar aging regarding materials impregnated with thyme and clove extracts have not been reported to date. Moreover, CE was found to be the most effective modifying agent for enabling material with antimicrobial activity against Escherichia coli to be obtained.

Ammoides pusilla Essential Oil: A Potent Inhibitor of the Growth of Fusarium avenaceum and Its Enniatin Production.

Enniatins are mycotoxins produced by Fusarium species contaminating cereals and various agricultural commodities. The co-occurrence of these mycotoxins in large quantities with other mycotoxins such as trichothecenes and the possible synergies in toxicity could lead to serious food safety problems. Using the agar dilution method, Ammoides pusilla was selected among eight Tunisian plants for the antifungal potential of its essential oil (EO) on Fusarium avenaceum mycelial growth and its production of enniatins. Two EO batches were produced and analyzed by GC/MS-MS. Their activities were measured using both contact assays and fumigant tests (estimated IC50 were 0.1 µL·mL-1 and 7.6 µL·L-1, respectively). The A. pusilla EOs and their volatiles inhibited the germination of spores and the mycelial growth, showing a fungistatic but not fungicidal activity. The accumulation of enniatins was also significantly reduced (estimated IC50 were 0.05 µL·mL-1 for the contact assays and 4.2 µL·L-1 for the fumigation assays). The most active batch of EO was richer in thymol, the main volatile compound found. Thymol used as fumigant showed a potent fungistatic activity but not a significant antimycotoxigenic activity. Overall, our data demonstrated the bioactivity of A. pusilla EO and its high potential to control F. avenaceum and its enniatins production in agricultural commodities.