Concentrations Of Thymol Research Articles

Определение тимола с предварительным мицеллярно-экстракционным концентрированием

For the efficient preconcentration of azo compounds – products of the interaction of 4-nitrophenyldiazonium with thymol, a system 4-nitroaniline (4-NA) – NO2- – Triton X-100 – NaOH – ethanol has been proposed. The optimal conditions for the formation of micellarsaturated phases of the system under study have been established: 3.10-4 M 4-NA – 3.10-4 M NO2- – 5% Triton X-100 – 2.8 M NaOH – 10 vol. % С 2Н5ОН. A spectrophotometric study of the above system has been carried out. A linear dependence was built in the coordinates A (at λ max = 552 nm) vs с(thymol), which is described by an equation of the form A = f(c), A = 26291c + 0.02; R2 = 0.997. The range of the determined contents of thymol is (2·10-6 – 4·10-5) mol/l. A technique for the colorimetric determination of thymol in aqueous media (color channel G) has been developed. The intensity of the channel G chromaticity (IG) is linearly dependent on pc(thymol) in accordance with the equation IG = 54.2pc – 267, R 2 = 0; the lower limit of the determined contents of thymol is 1.10-6 mol/l, which is two times less than in the variant of its spectrophotometric determination. The profiles of petal diagrams in the color coordinates of the RGB CMYK model have been constructed; the dependences of their area (S) and perimeter (P) on the thymol concentration have been obtained (P: y = 278x – 10.13; R 2 = 0.97; S: y = 20182x – 87649, R 2 = 0.99).

Effect of Sustained Administration of Thymol on Its Bioaccessibility and Bioavailability in Rabbits.

Simple SummaryThe purpose of this study was to investigate the bioavailability and metabolic path of thymol, a major constituent of Thymus vulgaris L., in the rabbit organism. Oral bioavailability is a key parameter affecting the efficacy of substances, but it is not surprising that it does not correlate satisfactorily with efficacy. The main limitation factors are rate of absorption, metabolism, and excretion processes. In this work, the thymol metabolic path in the rabbit organism was determined for the first time after its sustained oral administration. We confirm intensive absorption of thymol from the gastrointestinal tract; our results point to metabolism and accumulation in kidney tissue and intensive metabolic and excretion processes in the liver. Some metabolic processes were present also after thymol withdrawal. Thymol as a lipophilic substance was found only in trace amounts in fat and muscle tissue as a consequence of its conversion into hydrophilic metabolite and greater elimination in the rabbit organism. This paper highlights the insufficient knowledge of modes of action of plant compounds in animal organisms.The objective of this study was the detection of thymol in rabbit plasma, tissues, large intestinal content, and faeces. Forty-eight rabbits were divided into control and experimental groups (thymol 250 mg/kg feed). Thymol was administered for 21 days and then withdrawn for 7 days. Concentration of thymol in the intestinal wall (IW) was significantly higher than in plasma (p < 0.05) and liver (p < 0.05); in the kidneys it was significantly higher than in plasma (p < 0.05) and liver (p < 0.05) during thymol addition. Thymol in IW was significantly higher than in plasma also after withdrawal (p < 0.01). Significant correlation (rs = −1.000, p < 0.01) between IW and plasma points to the intensive absorption of thymol from the intestine, while the correlation between plasma and liver (rs = 0.786, p < 0.05) indicates intensive biotransformation and excretion processes in liver. Significant correlation between liver and kidney (rs = 0.738, p < 0.05) confirms the intensive metabolism of thymol in the kidney. During the withdrawal period, thymol was detected above trace amounts only in faeces, and was significantly higher than in the colon during both periods (p < 0.01). Results show intensive biotransformation of thymol in the rabbit organism.

A Design of Experiment (DoE) Approach to Model the Yield and Chemical Composition of Ajowan (Trachyspermum ammi L.) Essential Oil Obtained by Microwave-Assisted Extraction.

Ajowan (Trachyspermum ammi L.) is a spice traditionally used in Middle Eastern medicine and contains a valuable essential oil (EO) exploited in different fields, such as pharmaceutics, agrochemicals and food additives. This EO is mostly characterized by the thymol to which most of its biological properties are related. Given the economic value of ajowan and its increasing demand across the globe, the extraction method used for its EO is of paramount importance in terms of quality and quantity of the final product. In the present study, we used the design of experiment (DoE) approach to study and optimize the extraction of the ajowan EO using the microwave-assisted extraction (MAE), a novel extraction technique with high efficiency, low energy consumption, short process length and low environmental impact. A two-step DoE (screening followed by surface response methodology) was used to reduce the number of experiments and to improve the cost/benefit ratio. Reliable mathematical models, relating the more relevant EO features with the extraction conditions, were obtained and used to identify the best experimental conditions able to maximize the yield and thymol concentration. The optimized MAE procedure assures an EO with a higher yield and thymol amount compared with the standard hydrodistillation procedure.

Kraft lignin as a partial replacement for a traditional surfactant in thymol-based biocidal suspensions: physical and chemical features

Thymol is a renewable substance and has a high antimicrobial efficiency, which indicates that it could be used to produce sustainable biocides. In this study, we used kraft lignin as a partial replacement for a traditional surfactant in order to solubilize thymol in water. In this sense, this article reports an unprecedented method for using a kraft lignin solution to stabilize a thymol-based biocide with high fungicidal activity. The results showed that the lignin was crucial for stabilizing the suspensions. When the lignin was not added to the surfactant, there was a water-oil phase separation and the thymol crystallized after its rest for 30 days. Results obtained by in vitro experiments indicated that one of the studied lignin:thymol suspension (volume ratio of 1:0.1) presented an excellent fungal resistance. Furthermore, even the sample with the smallest thymol concentration (c.a. 0.5%) was able to inhibit the mycelial growth of the bracket fungus (Ganoderma applanatum), which is a promising feature for a biocidal application. HIGHLIGHTS This research addresses multidisciplinary concepts for obtaining sustainable products; Lignin is a good renewable stabilizer for thymol suspensions in water; Thymol and lignin, at three different mass ratios, were successfully applied for obtaining stable suspensions; Lignin-thymol suspensions seem to be promising biocides.

Antifungal activity of Zataria multiflora Boiss. essential oils and changes in volatile compound composition under abiotic stress conditions

There is an increasing need for natural compounds for pest control and food preservation in agriculture, food and dairy industries. To satisfy this need, essential oils (EOs) from aromatic plants can serve as flavors, food preservatives and ecofriendly pesticides. This study investigated the potential of different EOs from field-collected leaves of fourteen Zataria multiflora Boiss. populations representing three different chemotypes (carvacrol, thymol and linalool) to inhibit a broad spectrum of fungal pathogens important in food industry and agriculture and the relationship between total leaf elements concentration and EOs compounds. Furthermore, a greenhouse experiment was performed to elucidate the effects of heat stress (33 °C vs. 20 °C), drought stress (50 % reduced irrigation), and ultraviolet light intensity (3, 6 and 9 W m−2 UV-A radiation) on the relative content of specific volatile compounds. The results indicated that low concentrations of carvacrol and thymol, but not of linalool chemotype EOs inhibit significantly the growth of pre- and postharvest pathogens Colletotrichum lindemuthianum, Fusarium sambucinum, Fusarium culmorum, Alternaria dauci and Botrytis cinerea (thymol/carvacrol EOs: 0.8−1 μL, linalool EOs: 4 μL). The analyses revealed further significant correlations between the concentrations of mineral elements in Z. multiflora leaves and relative amounts of EO compounds and antifungal activity. Abiotic stresses, particularly heat and the interaction of drought and heat, induced changes in plants of the linalool chemotype resulting in higher relative amounts of carvacrol (22.7 % and 32.9 % vs. 1.5 %), while drought stress alone did not influence the relative amount of the main volatile compounds of Z. multiflora (carvacrol 1.7 %). Furthermore, the relative amount of linalool was slightly reduced in the linalool chemotype, when plants were subjected to high intensities of UV-A radiation (33.9 % vs. 44.6 %), whilst the relative amount of carvacrol was slightly increased (20.1 % vs. 9%). Moreover, the main volatile compounds of plants from the carvacrol chemotype did not change in response to abiotic stresses. Understanding the effect of environmental conditions on aromatic plant populations and chemotype development helps agriculture and food industry fully exploiting the potential of aromatic plants as a source of natural sustainable fungicides or insecticides.

Staphyloxanthin inhibitory potential of thymol impairs antioxidant fitness, enhances neutrophil mediated killing and alters membrane fluidity of methicillin resistant Staphylococcus aureus

Staphylococcus aureus is a leading pathogen responsible for mild to severe invasive infections in humans. Especially, methicillin resistant Staphylococcus aureus (MRSA) is prevalent in hospital and community associated infections. Staphyloxanthin is a golden yellow color eponymous pigment produced by S. aureus and provides resistance to reactive oxygen species (ROS) and host neutrophil-based killing. In addition, this membrane pigment contributes to membrane rigidity and helps MRSA to survive under stress conditions. Targeting virulence of pathogen without exerting selection pressure is the recent approach to fight bacterial infections without developing drug resistance. The present study for the first time evaluated the staphyloxanthin inhibitory potential of thymol against MRSA. Qualitative and quantitative analyses demonstrated 90% of staphyloxanthin inhibition at 100 µg/mL concentration of thymol without alteration in growth. Molecular docking analysis and in vitro measurement of metabolic intermediates of staphyloxanthin revealed that thymol could possibly interact with CrtM to inhibit staphyloxanthin. Absorbance and infra red spectra further validated the inhibition of staphyloxanthin by thymol. In addition, thymol treatment significantly reduced the resistance of MRSA to ROS and neutrophil-based killing as exhibited by oxidant susceptibility assays and ex vivo innate immune clearance assay using human whole blood and neutrophils. Further, reduction in staphyloxanthin by thymol treatment increased the membrane fluidity and made MRSA cells more susceptible to membrane targeting antibiotic polymyxin B. Especially, thymol was found to be non-cytotoxic to human peripheral blood mononuclear cells. Our study validated the antivirulence potential of thymol against MRSA by inhibiting staphyloxanthin and suggests the prospective therapeutic role of thymol to combat MRSA infections.

Investigation on amitraz, coumaphos and thymol concentrations in honey produced by Slovenian beekeepers in 2020

A survey on concentrations of veterinary drug residues amitraz, coumaphos and thymol in honey, produced in year 2020 by Slovenian beekeepers, was conducted. 100 samples were analysed: 22 from organic and 78 from conventional production, with two analytical methods. In method for determination of coumaphos and thymol samples were extracted with acetone, petroleumether and dichlorometane. In method for determination of amitraz and its degradation products, samples were hydrolisated with HCl and NaOH, extractied with n-hexane and derivatisated with heptafluorobutyric anhydride. Determination in both methods was performed with gas chromatograph coupled with mass spectrometer. Measured concentrations of amitraz, coumaphos and thymol were in the range of 0.01-0.12 mg kg-1, 0.02-0.06 mg kg-1 and 0.08-0.17 mg kg-1, respectively. In 61 % of samples analysed no residues of amitraz, thymol and coumaphos were found. Data obtained were compared with the data from literature. Chronic and acute exposure were calculated for consumers. Maximum chronic exposure for amitraz and thymol was 0.1 % and 0.05 % of acceptable daily intake, respectively. Maximum acute exposure for amitraz and thymol was 4 % and 0.8 % of acute reference dose, respectively

Presence, persistence and distribution of thymol in honeybees and beehive compartments by high resolution mass spectrometry

Thymol has been considered as an organic varroacide with less toxicity than synthetic chemicals such as amitraz, coumaphos or tau-fluvalinate. The present study evaluates the presence, persistence and distribution of thymol during a five-month sampling period; before, during and after the application of thymol treatment in field conditions. Moreover, its impact on the development of bee brood was also studied at different development stages which consist of larvae, prepupae, pupae and adult honeybee. Samples of beebread (processed pollen), honey, beeswax, adult bees, pupae, prepupae and larvae were analysed by gas chromatography coupled to time of flight mass spectrometry for an accurate identification. Adult bees were the samples with the highest concentration level of thymol during treatment application (Thymovar® strips, 30 gr of thymol per hive) by the beekeeper, however they showed 69% of thymol dissipation three months after treatment. Regarding the bee brood, concentrations of thymol decreased significantly (89-97% of disappearance) in a period of three months, though about 42 µg/kg of thymol persisted in larvae. Thymol was found to accumulate in honey and beeswax at a level of 882 μg/kg and 1305 μg/kg respectively, in the studied period. As the main issue of thymol residues in honey is related to the modification of organoleptic properties, more than toxicology, the levels found in this study indicate that the taste of honey may be affected during and up to three months after the treatment application. In addition, we did not find adverse effects on the evolution of the colonies due to the applied treatment.

Essential Oils of Four Virginia Mountain Mint (Pycnanthemum virginianum) Varieties Grown in North Alabama.

Virginia mountain mint (Pycnanthemum virginianum) is a peppermint-flavored aromatic herb of the Lamiaceae and is mainly used for culinary, medicinal, aromatic, and ornamental purposes. North Alabama’s climate is conducive to growing mint for essential oils used in culinary, confectionery, and medicinal purposes. There is, however, a need for varieties of P. virginianum that can be adapted and easily grown for production in North Alabama. Towards this end, four field-grown varieties with three harvesting times (M1H1, M1H2, M1H3; M2H1, M2H2, M2H3; M3H1, M3H2, M3H3, M4H1, M4H2, M4H3) were evaluated for relative differences in essential oil yield and composition. Thirty-day-old greenhouse-grown plants of the four varieties were transplanted on raised beds in the field at the Alabama A & M University Research Station in North Alabama. The plots were arranged in a randomized complete block with three replications. The study’s objective was to compare the four varieties for essential oil yield and their composition at three harvest times, 135, 155, and 170 days after planting (DAP). Essential oils were obtained by hydrodistillation with continuous extraction with dichloromethane using a Likens–Nickerson apparatus and analyzed by gas chromatographic techniques. At the first harvest, the essential oil yield of the four varieties showed that M1H1 had a yield of 1.15%, higher than M2H1, M3H1, and M4H1 with 0.91, 0.76, and 1.03%, respectively. The isomenthone concentrations increased dramatically through the season in M1 (M1H1, M1H2, M1H3) by 19.93, 54.7, and 69.31%, and M3 (M3H1, M3H2, M3H3) by 1.81, 48.02, and 65.83%, respectively. However, it increased only slightly in M2 and M4. The thymol concentration decreased slightly but not significantly in all four varieties; the thymol in M2 and M4 was very high compared with M1 and M3. The study showed that mountain mint offers potential for production in North Alabama. Two varieties, M1 and M3, merit further studies to determine yield stability, essential oil yield, composition, and cultivation development practices.

Phylogenetic analysis and protective effects of thymol and its chromatographic fractions from a novel wild mushroom in combating oxidative stress

Mushrooms are good sources of phytochemicals that have antioxidant and anti-proliferative effects. This study identified a unique isoform of 18S rRNA gene (864bp) from a novel wild mushroom (SMK-1) (GenBank accession number: SUB3267363). Thin layer chromatographic (TLC) profiling of the methanolic extract of the dried mushroom fruiting bodies of SMK-1 revealed the presence of phenolic and flavonoid fractions with retention factor (Rf) values of 0.955 and 0.927 respectively. The GC/MS chromatograms of the SMK-1 methanolic extract identified the main bioactive compound was phenol, 5-methyl-2-(1-methylethyl) (74.00%) (thymol). The radical scavenging activity for the flavonoid fraction was greater than the phenolic fractions (Rf–phenolics fractions>Rf–flavonoid fractions) with the antioxidant activity more than that of standard ascorbic acid. Also, the phenolic and flavonoid fractions of SMK-1 expressed cytotoxic effects in HeLa cells with IC50 values ranging from 5μg/mL to 80μg/mL in a dose-dependent manner. This present research highlights the presence of high thymol concentration in a novel wild mushroom that has antioxidant and anti-poliferative potential with therapeutic benefits. The application of thymol natural products from novel mushroom SMK-1 as nutrition supplements could inhibit oxidative stress triggered by numerous pathologies that may pave the way to develop a new therapeutic natural drug.

Development of an active packaging based on polyethylene containing linalool or thymol for mozzarella cheese.

The aim of this research was to evaluate the effect of active polyethylene film (PE) containing linalool and thymol active components on the microbial shelf life of mozzarella cheese. PE films containing different concentrations of linalool or thymol (0%, 1%, 1.5% and 2%) were prepared. The antimicrobial properties of the films were examined, and mozzarella cheese was packed with these active films. The antimicrobial properties of packed samples during 30 days of storage were studied. The obtained results from film tests showed that by increasing the concentration of active agents (linalool and thymol) in PE films, the antimicrobial activities of film samples against Escherichia coli, Staphylococcus aureus, Listeria innocua, and Saccharomyces cervicea were increased. The cheese tests result demonstrated that mozzarella cheese packaging with PE films containing different concentrations of linalool and thymol leads to a decreased growth rate of molds and yeasts in cheeses. At the end of the storage period, the lowest number of molds and yeasts was for a sample packed in PE film containing 2% thymol, which increased from 1.00 to 1.21 Log CFU/g during the storage period. From E. coli and S. aureus contamination, the samples packed in active films were safe until the last day of storage (30th day), while the control sample was unacceptable at 17th day of storage. According to obtained results from this study, it was concluded that the addition of linalool and thymol active components to PE film had a positive effect on the extension of the mozzarella scheese shelf life.

Comparative assessment of the disinfection effectiveness of thymol and benzalkonium chloride against adapted and non-adapted to thymol biofilm cells of a Salmonella Typhimurium epidemic phage type DT193 strain

Nowadays there is a need to develop cost-effective, safe, and preferably eco-friendly methods to combat the pathogenic and other detrimental robust biofilms. Ιn this work, the disinfection actions of thymol (THY), a phytocompound exhibiting wide antimicrobial action, and benzalkonium chloride (BAC), a synthetic biocide commonly used as surface disinfectant in the food industry and elsewhere, were comparatively evaluated against adapted and non-adapted to THY biofilm cells of a Salmonella enterica ser. Typhimurium epidemic phage type DT193 strain. Initially, the minimum inhibitory and bactericidal concentrations (MICs, MBCs) of each compound were determined against planktonic bacteria, together with their minimum biofilm inhibitory and eradication concentrations (MBICs, MBECs) against biofilms formed on polystyrene (PS). Bacteria were subsequently left to form biofilms on model stainless steel (SS) surfaces incubated in 1/10 diluted tryptone soy broth (dTSB) containing or not a sub-inhibitory THY concentration. Those sessile populations were finally submitted to disinfection (for 15 min) with THY or BAC and the viable biofilm bacteria were quantified by using in parallel agar plating and selective fluorescence staining. The results showed that when the terpenoid was applied at sub-MIC during biofilm formation, it was able to cause significant reductions of the final sessile populations on both surfaces (PS and SS). Disinfection results revealed the significant anti-biofilm action of THY on the non-adapted (control) biofilms (5 log reductions at MBC) and its superiority to that of BAC (<2 log reductions at 2 x MBC). However, the disinfection treatments applied on the THY-adapted biofilms were quite less efficient (achieving 2.6 and 1.3 log reductions, for THY and BAC, respectively). This demonstrates adaptation of Salmonella to THY, conferring co- and cross-disinfection resistance, as for many other antibacterial chemicals. Overall, the results demonstrate that natural compounds extracted from plants may be promising agents in helping to combat biofilms, multicellular microbial structures well-known for their remarkable hardiness against many stresses and antimicrobials.

Effects of nanocellulose fiber and thymol on mechanical, thermal, and barrier properties of corn starch films

This study explores the preparation of corn starch (CS) films incorporated with nanocellulose fiber (NCF) and different concentrations of thymol (0.1, 0.3, and 0.5% weight of thymol/volume of solution (% w/v)) via the solvent casting method. The resulting films were characterized by the functional chemistry, crystallinity, morphology, mechanical, thermal, and barrier properties. The Fourier transform infrared spectroscopy analysis confirmed the presence of intermolecular hydrogen bonding between the thymol and starch, as well as the thymol and glycerol, via hydroxyl groups of glycerol, starch, and thymol. The film crystallinity decreased with increasing concentration of thymol. The addition of NCF at 1.5% weight of starch increased the tensile strength (TS) and Young's Modulus (YM), but decreased the elongation at break (EAB), oxygen permeability, and water vapor permeability of the CS films. The thermal stability of the CS films was also improved with the addition of NCF. The addition of thymol to the CS/NCF bio-nanocomposite films decreased the TS and YM, respectively but increased the EAB due to the plasticizing effect of thymol. The addition of thymol also improved the thermal stability but reduced the barrier properties of the films. The effects on the mechanical, thermal, and barrier properties were more pronounced at higher concentrations of thymol. In conclusion, the inclusion of both NCF and thymol led to the improvement of the flexibility and thermal stability of the CS films.

Evaluation of the in vitro antibacterial activity of some essential oils and their blends against Staphylococcus spp. isolated from episodes of sheep mastitis

Staphylococcus aureus and coagulase-negative staphylococci are among the major causes of mastitis in sheep. The main goal of this research was to determine the in vitro antibacterial activity of several essential oils (EOs, n 30), then five of them were chosen and tested alone and in blends against staphylococci isolates. Five bacteria were isolated from episodes of ovine mastitis (two S. aureus and three S. xylosus). Biochemical and molecular methods were employed to identify the isolates and disk diffusion method was performed to determine their antimicrobial-resistance profile. The relative percentage of the main constituents in the tested essential oils and their blends was detected by GC-EIMS analysis. Antibacterial and bactericidal effectiveness of essential oils and blends were evaluated through minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). All of them showed sensitivity to the used antimicrobials. The EOs with the highest antibacterial activity were those belonging to the Lamiaceae family characterized by high concentrations of thymol, carvacrol and its precursor p-cymene, together with cinnamon EO, rich in cinnamaldehyde. In terms of both MIC and MBC values, the blend composed by Thymus capitatus EO 40%, Cinnamomum zeylanicum EO 20%, Thymus serpyllum EO 20% and Satureja montana EO 20% was found to be the most effective against all the isolates. Some essential oils appear to represent, at least in vitro, a valid tool against ovine mastitis pathogens. Some blends showed a remarkable effectiveness than the single oils, highlighting a synergistic effect in relation to the phytocomplex.

Diets supplemented with limonene and thymol modify intestinal histomorphology of Nile tilapia Oreochromis niloticus

Diets can influence the histomorphology of the gut of fish by either causing changes that are associated with growth promotion or causing damage that impairs fish growth. This study evaluated effects of diets with limonene and thymol on the histomorphology of the anterior intestine of Nile tilapia. A Nile tilapia diet was supplemented with different concentrations of limonene and/or thymol to form 6 diets, namely: 0 ppm limonene and thymol (Control); 400 ppm limonene (LM); 500 ppm thymol (T1); 750 ppm thymol (T2); 400 ppm limonene and 500 ppm thymol (LMT1); and lastly 400 limonene and 750 thymol (LMT2). Each diet was assessed in four tanks, each stocked with 35 fish of 1.60 g ± 0.24 and fed to satiation for 56 days. The length and number of intestinal folds, diameter of the lumen, status of lamina propria, and size of sub-mucosa were evaluated. Fish fed on diet LM and LMT1 had longer intestinal folds suggesting that diet LM and LMT1 increased the surface area covered by the intestinal folds and this is associated with increased nutrient absorption. The number of intestinal folds was not affected by the test diets. Treatment LMT1 had significantly narrow intestinal lumen potentially due to the elongated intestinal folds observed with dietary LMT1. Fish fed on diet T2 had enlarged lamina propria infiltrated with cells while the sub mucosa was larger in the anterior intestine of fish fed on diet LMT2 and the control feed. Enlarged lamina propria and intestinal sub mucosa indicate an inflammatory response and inefficient passage for blood and nutrients in the enterocytes in the intestine, potentially affecting efficient nutrient absorption. Overall, the diet with 400 ppm limonene and the dietary combination of 500 ppm thymol and 400 ppm limonene increased the surface area covered by intestinal folds indicating that they can enhance nutrient absorption in juvenile Nile tilapia.

Anesthetic efficacy of two plant phenolics and the physiological response of juvenile Ictalurus punctatus to simulated transport

The live transport of juvenile channel catfish (Ictalurus punctatus) is an important part of channel catfish breeding in China, but the anesthetic dose and physiological response of channel catfish after transport have not been studied yet. The purpose of this study was to assess the potential of eugenol and thymol in live transport and study their anesthetic effects of on juvenile channel catfish by analyzing a large number of parameters associated with stress and nonspecific immunity. First we tested eugenol and thymol concentrations of 10, 20, 30, 40, 50, and 100 mg/L. Eugenol successfully anesthetized the experimental fish at concentrations of 30–100 mg/L for 1258–82 s (resuscitation time was 147–300 s), while thymol was effective at 20–100 mg/L for 1612–81 s (recovery time was 333–475 s). The second experiment involved adding 10 and 20 mg/L of eugenol and thymol (4 groups) to the water, simulating transport (5 h), analyzing the stress and non-specific immune parameters of the serum, and determining gene expression changes in the liver and head kidney for 48 h. Anesthetics in the transport water inhibited the increase in serum cortisol levels (treatment group: 39.81–60.79 ng/mL, control group: 142.14 ng/mL), and Hsp90 in the liver was a more suitable biomarker for transport stress in channel catfish than Hsp70. Concentrations of serum total Ig, lysozyme, lectin, and ACH50, as well as the expression levels of cytokines (IL-1β, IL-8, and TNF-α) and pattern recognition receptors (NOD-1) in the head kidney increased. The expression of cytokines and NOD-1 in the head kidney returned to the pre-transport level after 48 h. Both anesthetics are suitable for channel catfish, but thymol is more suitable as a transport sedative. The results of this study could help maintain the health of juvenile channel catfish after live transport, decrease their infection and mortality, improve wellbeing, and reduce economic losses to the aquaculture industry.

Effect of yogurt-based marinade combined with essential oils on the behavior of Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella spp. in camel meat chunks during storage

The present study evaluated the effect of yogurt-based marinade combined with active essential oil components (EOs) namely: thymol (TH), carvacrol (CA), and cinnamaldehyde (CI) on Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella spp. in camel meat (CM) chunks during storage at 4 and 10 °C. Fresh cocktail mixtures of L.monocytogenes, E. coli O157:H7 and Salmonella spp. strains were inoculated on CM samples. Subsequently, a yogurt-based marinade, with or without 1% or 2% of the added EOs, was mixed with the CM chunks. After treatment, marinated camel samples were stored at 4 and 10 °C for 0, 1, 4 and 7 days. Adding yogurt-based marinade to the CM samples did not cause any significant changes in L.monocytogenes, E. coli O157:H7 and Salmonella spp. numbers at 4 °C, but at 10 °C resulted in a significant decrease in numbers on day 4 and 7 of storage by 1.4–1.5; 2.7–2.1 and 2.5–2.8 log CFU/g, respectively, compared to untreated CM samples. The incorporation of EOs into the CM with marination (CMM) further enhanced the microbial reduction of E. coli O157:H7 and Salmonella. At 10 °C, the synergistic effect of EOs with marinade was greater than at 4 °C. Increasing the concentration of the EOs used in this study from 1% to 2%, enhanced E. coli O157:H7 and Salmonella spp. reduction during storage at 4 and 10 °C while L.monocytogenes numbers were not affected. Increasing active EO component concentrations to 2% caused further significant reductions in Salmonella spp. in the CMM samples during storage by 1.0–2.7 log CFU/g (P ˂ 0.05) at 4 and 10 °C. At 10 °C, increasing the concentration of CI and TH to 2% caused a further reduction (P ˂ 0.05) of E. coli O157:H7 numbers by days 4 and 7 in the range of 3.6–4.4 log CFU/g. Among all tested EOs, 2% TH and 2% CI had the greatest effect against E. coli O157:H7 and Salmonella spp. in CMM during storage at 4 and 10 °C. In comparison to CMM, the highest scores of all examined sensory attributes were found in CMM samples with 1% and 2% CI added. Results indicate that the EO component CI can be used as an effective tool to decrease populations of E. coli O157:H7 and Salmonella spp. in CM with minor sensory changes.

Corn Starch/Chitosan Nanoparticles/Thymol Bio-Nanocomposite Films for Potential Food Packaging Applications.

This work aims to develop corn starch/chitosan nanoparticles/thymol (CS/CNP/Thy) bio-nanocomposite films as potential food packaging materials that can enhance the shelf life of food. CS/CNP/Thy bio-nanocomposite films were prepared by the addition of different concentrations of thymol (0, 1.5, 3.0, 4.5 w/w%) using a solvent casting method. The resulting films were characterized in terms of optical, mechanical, and water vapor permeability (WVP) properties. The addition of thymol was found to reduce the tensile strength (TS), elongation at break (EAB), and Young’s modulus (YM) of the films. Generally, the increment in the concentration of thymol did not significantly affect the TS, EAB, and YM values. The addition of 1.5 w/w% thymol increased the WVP of the films but the WVP reduced with the increase in thymol concentrations. CS/CNP/Thy-3% bio-nanocomposite films demonstrated the potential to lengthen the shelf life of cherry tomatoes packed with the films, whereby the cherry tomatoes exhibited no significant changes in firmness and the lowest weight loss. In addition, no mold growth was observed on the sliced cherry tomatoes that were in direct contact with the films during 7 days of storage, proving the promising application of the films as active food packaging materials.

Starch Edible Films/Coatings Added with Carvacrol and Thymol: In Vitro and In Vivo Evaluation against Colletotrichum gloeosporioides.

The aim of this work was to evaluate the in vitro and in vivo effectiveness of thymol and carvacrol added to edible starch films and coatings against Colletotrichum gloeosporioides. In vitro evaluation consisted of determining minimal inhibitory concentration (MIC) of carvacrol and thymol was determined at different pH values against Colletotrichum gloeosporioides. With MIC values, binary mixtures were developed. From these results, two coatings formulations were in vivo evaluated on mango and papaya. Physicochemical analysis, color change, fruit lesions and C. gloeosporioides growth were determined during storage. In vitro assay indicated that the MIC value of carvacrol and thymol against C. gloeosporioides was 1500 mg/L at pH 5. An additive effect was determined with 750/750 and 1125/375 mg/L mixtures of carvacrol and thymol, respectively. Coated fruits with selected mixtures of carvacrol and thymol presented a delay in firmness, maturity index and color change. Moreover, a fungistatic effect was observed due to a reduction of lesions in coated fruits. These results were corroborated by the increase in the lag phase value and the reduction of the growth rate. Carvacrol and thymol incorporated into edible films and coatings are able to reduce the incidence of anthracnose symptoms on mango and papaya.

Fabrication of pristine electrospun kafirin nanofiber mats loaded with thymol and carvacrol

In this project, we fabricated electrospun nanofiber mats from pristine kafirin, the storage protein of sorghum, for the first time which have the potential to be used as eco-friendly food packaging materials. The first novel step was kafirin extraction which showed that the purity of kafirin was higher in double-purification compared to single-purification, which led to high quality nanosized round, straight, unbroken and unentangled fibers. The electrospinning results indicate that binary solvent, 75% (v/v) acetic acid (AcOH) and 25% (v/v) butanol (BuOH) mixture, allows fabrication of homogenous nanofiber mats at 0.4 g/ml kafirin-to-solvent ratio, which is critical for to obtain good mechanical strength for the mats. Encapsulation of thymol and carvacrol was successful when the loading concentrations were 0.1 g/ml and 0.1–0.2 g/ml, for thymol and carvacrol, respectively. Loading of the fibers with the bioactives was confirmed with FTIR where the characteristic peaks for the bioactives appeared at 950 cm−1, 1150 cm−1, 1200 cm−1 and 1250 cm−1. Thymol or carvacrol encapsulation led to the conversion of some of the β-turn structures of kafirin into β-sheet structures. Surface hydrophilicity of loaded kafirin fiber mats decreased with increasing carvacrol concentration and increased with increasing thymol concentration.