Combined in vitro/in silico approaches, molecular dynamics simulations and safety assessment of the multifunctional properties of thymol and carvacrol: A comparative insight

Bioactive compounds derived from medicinal plants have acquired immense attentiveness in drug discovery and development. The present study investigated in vitro and predicted in silico the antibacterial, antifungal, and antiviral properties of thymol and carvacrol, and assessed their safety. The performed microbiological assays against Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica Typhimurium revealed that the minimal inhibitory concentration values ranged from (0.078 to 0.312 mg/mL) and the minimal fungicidal concentration against Candida albicans was 0.625 mg/mL. Molecular docking simulations, stipulated that these compounds could inhibit bacterial replication and transcription functions by targeting DNA and RNA polymerases receptors with docking scores varying between (-5.1 to -6.9 kcal/mol). Studied hydroxylated monoterpenes could hinder C. albicans growth by impeding lanosterol 14α-demethylase enzyme and showed a (ΔG=-6.2 and -6.3 kcal/mol). Computational studies revealed that thymol and carvacrol could target the SARS-Cov-2 spike protein of the Omicron variant RBD domain. Molecular dynamics simulations disclosed that these compounds have a stable dynamic behavior over 100 ns as compared to remdesivir. Chemo-computational toxicity prediction using Protox II webserver indicated that thymol and carvacrol could be safely and effectively used as drug candidates to tackle bacterial, fungal, and viral infections as compared to chemical medication.

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.

Evaluating protective effects of botanicals under inflammation and oxidative stress in chicken apical-out enteroids

Botanicals (BOTs) are well known for their anti-inflammatory and antioxidant activities. They have been widely used as feed additives to reduce inflammation and improve intestinal functions in agricultural animals. However, the effects of BOTs on chicken intestinal epithelial functions are not fully understood. The 3D apical-out chicken enteroids recapitulate the intestinal tissue, and allow convenient access to the luminal surface, thus serving as a suitable model for investigating gut functions. The aim of this study was to identify the roles of BOTs in protecting the intestinal epithelium in chicken enteroids under challenging conditions. Apical-out enteroids were isolated from the small intestines of 18 days-old chicken embryos. Lipopolysaccharide (LPS, 10 µg/mL) and menadione (400 µM) challenges were performed in the media with or without BOTs. Paracellular Fluorescein isothiocyanate-dextran 4kD (FD4) permeability, inflammatory cytokine gene expression, and reactive oxygen species (ROS) generation were analyzed post-BOTs and challenges treatments. Statistical analysis was performed using one-way ANOVA and post hoc multiple comparisons among treatments. The results showed that the LPS challenge for 24 h induced a 50% increase in FD4 permeability compared with nontreated control; thymol, thyme essential oil, and phenol-rich extract significantly (P < 0.02) reduced FD4 permeability by 25%, 41%, and 48% respectively, in comparison with LPS treatment. Moreover, the gene expression of inflammatory cytokines was upregulated, tight junction proteins and defensins were downregulated (P < 0.05) after 6 h of LPS treatment, while these BOTs treatments significantly restored the LPS-induced gene expression alterations (P < 0.05). Menadione oxidative challenge for 1 h significantly increased the ROS level compared with unchallenged control. Enteroids treated with thymol and thyme essential oils showed 30% reduced ROS levels, while the phenol-rich extract reduced them by 60%, in comparison with the challenged group (P < 0.0001). These data confirmed the role of BOTs in supporting the barrier function and reducing the disruptive effects of inflammation and oxidation in the chicken intestine.

Dietary supplementation with a microencapsulated complex of thymol, carvacrol, and cinnamaldehyde improves intestinal barrier function in weaning piglets

BACKGROUND

The authors previously prepared a microencapsulated complex of thymol, carvacrol, and cinnamaldehyde (MEEO). This study aimed to evaluate the effect of MEEO on the intestinal mucosal barrier and homeostasis in weaning piglets. A comparison of the effect of MEEO versus chlortetracycline (CTC) was performed in this study.

RESULTS

Piglets were divided into three groups - control (Con), MEEO, and CTC groups - and raised for 28 days. The results showed that MEEO significantly elevated the ratio of the villus height and the crypt depth in the jejunum and decreased the crypt depth in the ileum compared with the other groups (P < 0.05); it also upregulated the messenger ribonucleic acid (mRNA) expression of tight junction protein in the small intestine. Compared with the Con group, MEEO increased the concentration of secretory immunoglobulin A (sIgA), cathelicidin antimicrobial peptides (CAMP), and interleukin 10 (IL-10), while decreasing the interleukin 1 beta (IL-1β) concentration in both jejunal and ileal mucosa (P < 0.05). The mRNA expression of jejunal mucosal MUC1 and ileal mucosal MUC2 was increased in the MEEO group compared with the other groups (P < 0.05). Intestinal microbial analysis showed that dietary treatment had little impact on the ileal microbial structure. A significant rise in the genus Lactobacillus was, however, found in the MEEO group. There is a positive correlation between the Lactobacillus and sIgA, and between the Lactobacillus and CAMP, indicating that an improvement in the mucosal barrier function by the addition of MEEO may be associated with the proliferation of Lactobacillus.

CONCLUSION

Dietary supplementation with MEEO improves intestinal barrier function in weaning piglets, the effect of which was superior to CTC. © 2022 Society of Chemical Industry.

The structure of AgamOBP5 in complex with the natural insect repellents Carvacrol and Thymol: Crystallographic, fluorescence and thermodynamic binding studies

Among several proteins participating in the olfactory perception process of insects, Odorant Binding Proteins (OBPs) are today considered valid targets for the discovery of compounds that interfere with their host-detection behavior. The 3D structures of Anopheles gambiae mosquito AgamOBP1 in complex with the known synthetic repellents DEET and Icaridin have provided valuable information on the structural characteristics that govern their selective binding. However, no structure of a plant-derived repellent bound to an OBP has been available until now. Herein, we present the novel three-dimensional crystal structures of AgamOBP5 in complex with two natural phenolic monoterpenoid repellents, Carvacrol and Thymol, and the MPD molecule. Structural analysis revealed that both monoterpenoids occupy a binding site (Site-1) by adopting two alternative conformations. An additional Carvacrol was also bound to a secondary site (Site-2) near the central cavity entrance. A protein-ligand hydrogen-bond network supplemented by van der Waals interactions spans the entire binding cavity, bridging α4, α6, and α3 helices and stabilizing the overall structure. Fluorescence competition and Differential Scanning Calorimetry experiments verified the presence of two binding sites and the stabilization effect on AgamOBP5. While Carvacrol and Thymol bind to Site-1 with equal affinity in the submicromolar range, they exhibit a significantly lower and distinct binding capacity for Site-2 with Kd's of ~7 μΜ and ~18 μΜ, respectively. Finally, a comparison of AgamOBP5 complexes with the AgamOBP4-Indole structure revealed that variations of ligand-interacting aminoacids such as A109T, I72M, A112L, and A105T cause two structurally similar and homologous proteins to display different binding specificities.

Creation of new germplasm resources, development of SSR markers, and screening of monoterpene synthases in thyme

BACKGROUND

Thyme derived essential oil and its components have numerous applications in pharmaceutical, food, and cosmetic industries, owing to their antibacterial, antifungal, and antiviral properties. To obtain thyme essential oil with different terpene composition, we developed new germplasm resources using the conventional hybridization approach.

RESULTS

Phenotypic characteristics, including essential oil yield and composition, glandular trichome density, plant type, and fertility, of three wild Chinese and seven European thyme species were evaluated. Male-sterile and male-fertile thyme species were crossed in different combinations, and two F₁ populations derived from Thymus longicaulis (Tl) × T. vulgaris 'Fragrantissimus' (Tvf) and T. vulgaris 'Elsbeth' (Tve) × T. quinquecostatus (Tq) crosses were selected, with essential oil yield and terpene content as the main breeding goals. Simultaneously, simple sequence repeat (SSR) primers were developed based on the whole-genome sequence of T. quinquecostatus to authenticate the F₁ hybrids. A total of 300 primer pairs were selected, and polymerase chain reaction (PCR) was carried out on the parents of the two hybrid populations (Tl, Tvf, Tve, and Tq). Based on the chemotype of the parents and their F₁ progenies, we examined the expression of genes encoding two γ-terpinene synthases, one α-terpineol synthase, and maybe one geraniol synthase in all genotypes by quantitative real-time PCR (qRT-PCR).

CONCLUSION

We used hybridization to create new germplasm resources of thyme, developed SSR markers based on the whole-genome sequence of T. quinquecostatus, and screened the expression of monoterpene synthase genes in thyme. The results of this study provide a strong foundation for the creation of new germplasm resources, construction of the genetic linkage maps, and identification of quantitative trait loci (QTLs), and help gain insight into the mechanism of monoterpenoids biosynthesis in thyme.

Carcass characteristics and meat evaluation of cattle finished in temperate pasture and supplemented with natural additive containing clove, cashew oil, castor oils, and a microencapsulated blend of eugenol, thymol, and vanillin

BACKGROUND

Forty crossbred steers were supplemented with different doses (from 0 control to 6000 mg/animal/day) of natural additive blend containing clove essential oil, cashew oil, castor oil, and a microencapsulated blend of eugenol, thymol, and vanillin for 80 days. Carcass characteristics, drip loss, and antioxidant activity were evaluated 24 h post mortem on longissimus thoracis, and the effects of aging (until 14 days) were evaluated for water losses (thawing/aging and cooking), texture, color, and lipid oxidation.

RESULTS

The use of the natural additive blend did not modify (P > 0.05) carcass characteristics but did, however, modify body composition (P < 0.05). Drip losses were unaffected by the treatments tested (P > 0.05). There was an observed quadratic effect (P < 0.05) on losses from thawing/aging on the first day of storage. Regarding the effects of natural additives on cooking losses, there was a quadratic effect (P < 0.05) among the treatments on day 7 of aging. Differences between days of aging were only observed with control treatment. Shear force was similar among treatments on days 1 and 7 of aging. On day 14 a linear effect (P < 0.05) was observed. Also, a linear effect (P < 0.05) appeared on meat lightness, meat from the control group being clearer on day 1. No changes were observed in redness among treatments or days of storage (P > 0.05). Yellowness was not modified by the treatments (P > 0.05)but only by the days of storage in control and the lowest dosage used.

CONCLUSION

The blend of natural additives has potential use in pasture feeding and could improve meat quality. However, doses should be adjusted. © 2021 Society of Chemical Industry.

Thymol improves salinity tolerance of tobacco by increasing the sodium ion efflux and enhancing the content of nitric oxide and glutathione

BACKGROUND AND OBJECTIVE

Salt stress is one of the most important abiotic stresses affecting the yield and quality of tobacco (Nicotiana tabacum). Thymol (a natural medicine) has been widely used in medical research because of its antibacterial and anti-inflammatory activities. However, the influence of thymol on the root growth of tobacco is not fully elucidated. In this study, the regulatory effects of different concentrations of thymol were investigated.

METHODOLOGY

Here, histochemical staining and biochemical methods, non-invasive micro-test technology (NMT), and qPCR assay were performed to investigate the effect of thymol and mechanism of it improving salinity tolerance in tobacco seedlings.

RESULTS

In this study, our results showed that thymol rescued root growth from salt stress by ameliorating ROS accumulation, lipid peroxidation, and cell death. Furthermore, thymol enhanced contents of NO and GSH to repress ROS accumulation, further protecting the stability of the cell membrane. And, thymol improved Na+ efflux and the expression of SOS1, HKT1, and NHX1, thus protecting the stability of Na+ and K+.

CONCLUSION

Our study confirmed the protecting effect of thymol in tobacco under salt stress, and we also identified the mechanism of it, involving dynamic regulation of antioxidant system and the maintenance of Na+ homeostasis. It can be a new method to improve salinity tolerance in plants.

Effect of Methyl Jasmonate on Thymol, Carvacrol, Phytochemical Accumulation, and Expression of Key Genes Involved in Thymol/Carvacrol Biosynthetic Pathway in Some Iranian Thyme Species

Thyme species are a good source of thymol and carvacrol, which play a key role in controlling diseases. For the first time, the expression patterns of γ-terpinene synthase (TPS2), CYP71D178, and CYP71D180 genes and the amount of phenolics compounds were evaluated in T. migricus and T. daenensis after different methyl jasmonate (MeJA) treatments. The highest thymol and carvacrol contents were observed in T. migricus (86.27%) and T. daenensis (17.87%) at MeJA 100 µM, which was consistent with the expression patterns of the three investigated genes. All species treated showed high total phenolic and flavonoid content compared to control plants for which the highest amounts were observed in T. vulgaris treated with 100 µM and 10 µM MeJA. Furthermore, in the 100 µM MeJA treatment, the relative expression of TPS2 and CYP71D178 in T. migricus increased 7.47 and 9.86-fold compared with the control, respectively. The highest level of CYP71D180 transcripts (5.15-fold) was also observed for T. daenensis treated. This finding highlights the notion that thymol was known as the dominant component of the essential oil rather than carvacrol in diffident thyme species. This implies that MeJA at different concentrations influenced metabolic pathways and induced expression changes, resulting in a rise in essential oil levels.

Effects of increasing dietary level of organic acids and nature-identical compounds on growth, intestinal cytokine gene expression and gut microbiota of rainbow trout (Oncorhynchus mykiss) reared at normal and high temperature

Organic acids (OA) and nature-identical compounds (NIC) such as monoterpenes and aldehydes are well-known growth and health promoters in terrestrial livestock while their application for fish production is recent and their mechanisms of action require further study. Hence, this study tested the increasing dietary level (D0, D250, D500, D1000; 0, 250, 500 and 1000 mg kg feed^-1 respectively) of a microencapsulated blend containing citric and sorbic acid, thymol and vanillin over 82 days on rainbow trout to assess the effects on growth, feed utilization, intestine cytokine gene expression and gut microbiota (GM). Furthermore, the effects on intestinal cytokine gene expression and GM were also explored after one week at high water temperature (23 °C). OA and NIC improved specific growth rate (SGR) and feed conversion rate (FCR) during the second half (day 40-82) of the feeding trial, while at the end of the trial protein (PER) and lipid efficiency (LER) increased with increasing dietary level. GM diversity and composition and cytokine gene expression analysis showed no significant differences in fish fed with increasing doses of OA and NIC (82 days) demonstrating the absence of inflammatory activity in the intestinal mucosa. Although there were no statistical differences, GM structure showed a tendency in clustering D0 group separately from the other dietary groups and a trend towards reduction of Streptococcus spp. was observed in the D250 and D1000 groups. After exposure to high water temperature, lower GM diversity and increased gene expression of inflammatory intestinal cytokines were observed for both inclusions (D0 vs. D1000) compared to groups in standard condition. However, the gene up-regulation involved a limited number of cytokines showing the absence of a substantial inflammation process able to compromise the functional activity of the intestine. Despite further study should be conducted to fully clarify this mechanism, cytokines up-regulation seems to be concomitant to the reduction of the GM diversity and, particularly, to the reduction of specific lactic acid bacteria such as Leuconostoc. The application of the microencapsulate blend tested can be a useful strategy to improve growth and feed utilization in rainbow trout under normal temperature conditions. According to the results organic acids and nature-identical compounds did not revert the effects triggered by the increased temperature of water.

Natural Antibiotic Oregano in Hydroxyapatite-Coated Titanium Reduces Osteoclastic Bone Resorption for Orthopedic and Dental Applications

Traditional infection prevention and treatment methods include synthetic antibiotics, which can cause severe adverse side effects. Carvacrol and thymol are biologically active monoterpenoid extractants from oregano leaves with antibiotic capabilities; however, little is known regarding their effects on bone tissue engineering. The objective of this work is to understand their effects on osteogenesis, specifically with osteoblast and osteoclast cells, from surface-modified Ti6Al4V with plasma sprayed hydroxyapatite (HA) coatings. This system is an alternative to cemented implants to aid in bone healing. Results reveal that full carvacrol release from the HA matrix is successful in aqueous environments and modulation of release kinetics can also be made using polycaprolactone (PCL) and polyethylene glycol (PEG) polymers. From HA-pressed disc samples in physiological pH, full carvacrol release is achieved in 10 days using PCL/PEG, about 95% release in 50 days using no polymer, and 60% in 50 days when using a PCL coating. Without polymer, full carvacrol release is achieved after 3 days from HA coatings in both physiological pH and acidic pH, mimicking the post-surgery environment. The release is assessed as a diffusion-based mechanism in phosphate-buffered saline but degradation-based mechanism in acetate buffer solution. Carvacrol and thymol show bacterial inhibition of Staphylococcus epidermidis and no cytotoxic effects on osteoblast proliferation in vitro. Carvacrol and thymol also induce a significant 7% reduction in osteoclast tartrate-resistant acid phosphatase (TRAP) activity, caused by poorly attached cellular morphologies, leading to an approximately 65% reduction in osteoclast resorption pit formation. Our goal is to demonstrate a natural medicinal system that can support bone healing while providing infection prevention and reducing costly revision surgeries for orthopedic and dental applications.

Acceptability by sensory and visual analyses of meat from Nellore heifers fed with natural additives and finished in feedlots

BACKGROUND

This study evaluated the acceptability (by sensorial and visual analyses) of meat from 40 Nellore heifers (finished in feedlots for 73 days) fed with different diets supplemented with essential oils (EOs) and an active principle blend. The five diets tested were: CON - a diet without essential oil and active principle blend (eugenol, thymol, and vanillin); ROS - a diet supplemented with rosemary EO; BLE - supplemented with a blend; BCL - a diet with clove EO+ blend; and BRC - a diet with rosemary, clove EOs + blend. The acceptability of diet and aging time was evaluated by consumers.

RESULTS

Diet affected consumer acceptability and visual analysis (meat color). The diets with EO and the blend showed better sensory acceptance by the consumers; meat aged for 7 days received higher scores than meat aged for 1 day. Meat from heifers that received both EOs + blend (BCL, BRC) obtained the highest scores in the visual evaluation.

CONCLUSION

The use of natural compounds in ruminant diets improves the sensory characteristics of meat without damaging visual acceptability and may be an alternative to the conventional additive market. © 2020 Society of Chemical Industry.

Sequencing and variation of terpene synthase gene (TPS2) as the major gene in biosynthesis of thymol in different Thymus species

Thyme (Thymus spp.) is a valuable genus of Lamiaceae family with different pharmaceutical and food properties. Thymol has also been considered as the major essential oil compound in most of the studied Thymus species. In this research, the gene encoding γ-terpinene synthase (Ttps2) was sequenced in T. vulgaris and in eight Iranian thymes including T. carmanicus, T. daenensis, T. fedtschenkoi, T. kotschyanus, T. migricus, T. pubescens, T. serpyllum, and T. trautvetteri. Genetic relationships based on terpene synthase genes were also determined among the studied species. Rapid Amplification of cDNA Ends (RACE) PCR was done to complete the sequence of all species. The cDNA of the studied species possessed an open reading frame ranging from 1788 to 1794 bp that encode for a protein of 596-598 amino acids, presenting all the conserved motifs characteristics of monoterpene synthases. The taxonomic status of Thymus species was determined based on eight reported sections. The species were classified in three major groups. The first and second group comprised species of Micantes and Mastichina sections. The third cluster included the species belonging to Serpyllum and Pseudothymbra sections. Overall, phylogenetic analysis according to whole sequence of Ttps2 gene can help providing insights in respect to its evolutionary process. Finally, clustering based on the amount of main essential oils components (thymol and carvacrol) was compared with that based on Ttps2 gene classification in the studied Thymus species, showing that clustering is not always in accordance.

Thymol feed supplementation in quail alters the percentages of nutritionally relevant egg yolk fatty acids: effects throughout incubation

BACKGROUND

Polyunsaturated fatty acids (PUFA) are crucial components of egg yolk and particularly prone to oxidative damage, generating losses of nutrients for embryonic development and influencing the quality of eggs for human consumption. The aim of this study was to evaluate whether dietary thymol (a natural antioxidant) is related to changes in quail egg yolk total (T), triglyceride (TG) and phospholipid (PL) fatty acid composition at different stages of embryo development. Thus female Japanese quail (100 days of age) were assigned to one of two dietary treatments (12 individuals each): CON (basal diet) or THY (0.0016 mol thymol day^-1 per bird). After 2 weeks of supplementation, eggs were incubated and samples were obtained at 0, 4 and 16 days of embryonic development.

RESULTS

In 0 day THY eggs, α-linolenic acid and n-3 PUFA in T and TG, docosahexaenoic acid and PUFA in T and arachidonic acid in TG were increased, while saturated fatty acids (SFA) in T were reduced. From 4 days on, PUFA, n-3 PUFA and SFA from T and TG in THY eggs were found to be similar to those of CON eggs. The changes in PL throughout incubation were similar in both dietary treatments.

CONCLUSION

Thymol would provide the embryo with PUFA for synthesis/deposition in membranes and/or assign to supply energy. Additionally, thymol supplementation would be advisable for the production of healthier table eggs. © 2017 Society of Chemical Industry.

Effects of organic acids and essential oils blend on growth, gut microbiota, immune response and disease resistance of Pacific white shrimp (Litopenaeus vannamei) against Vibrio parahaemolyticus

An 8-week feeding trial was undertaken to evaluate supplemental effects of AviPlus^® (AP), a blend of organic acids [citric acid, 25%; sorbic acid, 16.7%] and essential oils [thymol, 1.7%; vanillin, 1.0%], on growth, gut microbiota, innate immunity and disease resistance of Pacific white shrimp (Litopenaeus vannamei) against Vibrio parahaemolyticus. A basal experimental diet was formulated and supplemented with 0, 0.3, 0.6, 0.9 and 1.2 g kg^-1 AP to produce five test diets (Con, AP0.3, AP0.6, AP0.9 and AP1.2). Each diet was fed to triplicate groups of shrimp (0.2 ± 0.01 g, mean ± SE) to apparent satiation three times daily. Growth performance and survival rate were not significantly influenced by AP supplementation (P > 0.05). Significantly (P < 0.05) higher serum total protein was found in groups fed ≥ 0.6 g kg^-1 AP compared to control. Serum alkaline phosphatase and phenoloxidase activities were significantly increased in AP0.9 and AP1.2 groups. Also, the group received AP0.6 diet showed significantly higher glutathione peroxidase activity than control. Expression of gut pro-inflammatory genes including TNF-α, LITAF and RAB6A were down-regulated by AP administration. Gut microbiota analysis showed the significant enhancement of the operational taxonomic unit (OTU) diversity and richness indices by AP application. AP supplementation led to increased abundance of Firmicutes and a reduction in abundance of Proteobacteria. Also, dietary inclusion of 1.2 g kg^-1 AP led to a significant increase in the abundance of Lactobacillus in shrimp gut. The group offered AP0.3 diet showed significantly higher disease resistance than control group. Furthermore, AP application significantly enhanced relative expression of immune related genes including lysozyme, penaeidin and catalase at 48 h post challenge. In conclusion, these findings show that the tested organic acids and essential oils mixture beneficially affects intestinal microflora and improves immune response and disease resistance of L. vannamei.

Thymol Ameliorates Cadmium-Induced Phytotoxicity in the Root of Rice (Oryza sativa) Seedling by Decreasing Endogenous Nitric Oxide Generation

Thymol has been developed as medicine and food preservative due to its immune-regulatory effect and antimicrobial activity, respectively. However, little is currently known about the role of thymol in the modulation of plant physiology. In the present study, we applied biochemical and histochemical approaches to investigate thymol-induced tolerance in rice (Oryza sativa) seedlings against Cd (cadmium) stress. Thymol at 20 μM recovered root growth completely upon CdCl₂ exposure. Thymol pronouncedly decreased Cd-induced ROS accumulation, oxidative injury, cell death, and Cd²⁺ accumulation in roots. Pharmaceutical experiments suggested that endogenous NO mediated Cd-induced phytotoxicity. Thymol decreased Cd-induced NO accumulation by suppressing the activity of NOS (nitric oxide synthase) and NR (nitrate reductase) in root. The application of NO donor (SNP, sodium nitroprusside) resulted in the increase in endogenous NO level, which in turn compromised the alleviating effects of thymol on Cd toxicity. Such findings may helpful to illustrate the novel role of thymol in the modulation of plant physiology, which may be applicable to improve crop stress tolerance.

Tissue-specific gene-expression patterns of genes associated with thymol/carvacrol biosynthesis in thyme (Thymus vulgaris L.) and their differential changes upon treatment with abiotic elicitors

Thyme (Thymus vulgaris L.) is known to produce a variety of phenolic monoterpenes such as thymol and carvacrol. Thymol and carvacrol are health-promoting, biocide and antitoxin compounds and have been considered as the main constituents of essential oils in T. vulgaris. To improve our understanding of the regulation of monoterpene biosynthesis in thyme, the expression of genes related to thymol and carvacrol biosynthesis in different tissues and in response to abiotic elicitors was analyzed. Methyl jasmonate (MeJA), salicylic acid (SA), trans-cinnamic acid (tCA) and UV-C irradiation were applied to T. vulgare leaves and transcript levels of early (DXR) and late (TvTPS1, CYP71D178 and CYP71D180) biosynthetic genes of thymol and carvacrol were measured. The results showed that early step and late step genes in thymol/carvacrol biosynthesis are differentially regulated. DXR was not found to be exclusively expressed in glandular trichomes; in contrast, biosynthetic genes including γ-terpinene synthase (TvTPS1) and two cytochrome P450s, CYP71D178 and CYP71D180, were preferentially expressed in glandular secretory trichomes. The high expression of late biosynthetic genes in glandular trichomes, which also contain the highest concentration of thymol and carvacrol, suggests that glandular trichomes are the structure in which thymol/carvacrol biosynthesis and accumulation occur. Our results indicate that in addition to abiotic elicitors, developmental and spatial factors also play a key role in the biosynthesis of thymol and carvacrol, most likely relating to glandular trichome density and/or activity. Hence optimization of these factors could be considered as a useful strategy to achieve high yield of valuable compounds in T. vulgare or other closely related plant species.

Effect of Thyme Essential Oil Supplementation on Thymol Content in Blood Plasma, Liver, Kidney and Muscle in Broiler Chickens

The absorption and metabolism of phytogenic feed additives in poultry is studied related to the metabolism and deposition of their main compounds in tissues intended for food production. Fifty-six non-sexed Ross 308 broilers were allocated to seven dietary treatments and fed a diet containing graded levels of thyme (Thymus vulgaris L.) essential oil (EO) (0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1%, w/w). Thymol concentration was measured in plasma, liver, kidney and breast muscle tissue using solid phase micro-extraction followed by gas chromatography/mass spectrometry. We found the highest concentrations of thymol in kidney and plasma, and the lowest in breast muscle and liver. Thymol content in plasma and kidney significantly increased when 0.05 and 0.1%, w/w, EO and in liver and breast muscle only when 0.1%, w/w, EO was added to the diet (p<0.05). Our results indicate intensive metabolism of thymol in liver and its accumulation in kidney tissue. We confirm low deposition of thymol in the muscle tissue. It is necessary to.-keep in mind the selection of a sufficient concentration of EO in the feed additive for animals without the risk of thymol residues in edible tissues.

Effects of thyme as a feed additive in broiler chickens on thymol in gut contents, blood plasma, liver and muscle

BACKGROUND

Aromatic herbs as feed additives in animal production are encountering growing interest, but data on the fate of the aromatic compounds from the plant in the animal body are very scarce. In the present study, thyme (Thymus vulgaris) herb consisting of leaves and flowers without stems was used as an ingredient in the diet for broilers. The herb was fed for 35 days to five groups of broilers (0, 0.1, 0.2, 0.3, and 1% w/w in the diet). Animal performance and the concentrations of the main essential oil component from thyme, thymol, were measured in gut contents, plasma and liver and muscle tissues using solid phase microextraction and gas chromatography/mass spectrometry.

RESULTS

There were no differences between the groups in feed intake, daily weight gain, feed conversion and slaughter weight. Thymol was detected in gut contents, plasma and liver and muscle tissues. Increased intestinal thymol concentrations were found in the group with 1% thyme compared with the other groups (P < 0.05). In liver and muscle tissues the thymol levels were close to the limit of quantification.

CONCLUSION

The data do not indicate a positive effect of thyme on animal performance. With high dietary levels of thyme herb, thymol concentrations increased in gut contents and plasma but were very low in edible tissues such as liver and flesh. © 2014 Society of Chemical Industry.

Thymol as an alternative to pesticides: persistence and effects of Apilife Var on the phototactic behavior of the honeybee Apis mellifera

Thymol is a natural substance increasingly used as an alternative to pesticides in the fight against the Varroa destructor mite. Despite the effectiveness of this phenolic monoterpene against Varroa, few articles have covered the negative or side effects of thymol on bees. In a previous study, we have found an impairment of phototaxis in honeybees following application of sublethal doses of thymol-lower or equal to 100 ng/bee-under laboratory conditions. The present work shows the same behavioral effects on bees from hives treated with Apilife Var®, a veterinary drug containing 74 % thymol, with a decrease in phototactic behavior observed 1 day after treatment. Thus, thymol causes disruption of bee phototactic behavior both under laboratory conditions as well as in beehives. The bee exposure dose in treated hives was quantified using gas chromatography coupled to mass spectrometry (GC-MS), giving a median value of 4.3 μg per body 24 h after treatment, with 11 ng in the brain. The thymol level in 20 organic waxes from hives treated with Apilife Var® was also measured and showed that it persists in waxes (around 10 mg/kg) 1 year after treatment. Thus, in the light of (1) behavioral data obtained under laboratory conditions and in beehives, (2) the persistence of thymol in waxes, and (3) the high load on bees, it would appear important to study the long-term effects of thymol in beehives.

Ex vivo absorption of thymol and thymol-β-D-glucopyranoside in piglet everted jejunal segments

Food-producing animals are reservoirs of Campylobacter, a leading bacterial cause of human foodborne illness. The natural product thymol can reduce the survivability of Campylobacter, but its rapid absorption in the proximal gastrointestinal tract may preclude its use as a feed additive to reduce intestinal colonization of these pathogens. This work examined the ex vivo absorption of thymol and thymol-β-d-glucopyranoside in everted porcine jejunal segments, as the latter was hypothesized to be more resistant to absorption. A modified gas chromatography and extraction method was developed to determine 1.0-500 mg/L thymol. From 1 and 3 mM solutions, 0.293 ± 0.04 and 0.898 ± 0.212 mM thymol, respectively, p = 0.0347, were absorbed, and 0.125 ± 0.041 and 0.317 ± 0.143 mM thymol-β-d-glucopyranoside, respectively, p = 0.0892, were absorbed. Results indicate that thymol-β-d-glucopyranoside was absorbed 2.3 to 2.8 times less effectively than thymol, thus providing evidence that thymol-β-d-glucopyranoside may potentially be used as a feed additive to transport thymol to the piglet lower gut.

Identification of CYP isoforms involved in the metabolism of thymol and carvacrol in human liver microsomes (HLMs)

Carvacrol and thymol are phenolic compounds with similar structures isolated from many aromatic plants, and have been demonstrated to exert multiple pharmacological effects. The metabolic and pharmacokinetic behaviour of thymol and carvacrol has received much attention. Carvacrol and thymol have been demonstrated to undergo phase I metabolism such as hydroxylation reaction. However, drug-metabolizing enzymes involved in this process remain unclear. Given that cytochrome P450s (CYPs) are involved in most phase I metabolism, the aim of the present study was to investigate the role of CYPs in the metabolism of thymol and carvacrol. After incubation with human liver microsomes (HLMs) in the presence of NADPH, a new metabolite and two metabolites were detected for thymol and carvacrol, respectively. A combination of chemical inhibition studies and assays with recombinant CYP isoforms demonstrated that CYP2A6 was the predominant drug-metabolizing enzyme involved in the metabolism of thymol and carvacrol. All these results remind the researchers that special attention should be paid on pharmacokinetic and clinical outcomes when thymol or carvacrol was co-administrated with other compounds mainly undergoing CYP2A6-mediated metabolism.

Microbial transformation of citral by Penicillium sp

Thymol is present in the essential oils from herbs and spices, such as thyme. It is produced by these plant species as a chemical defense against phytopathogenic microorganisms. Therefore, this compound has attracted great attention in food industry, i.e., it has been used as a natural preservative in foods such as cheese to prevent fungal growth. Previous studies concerning the biotransformation of nerol by Penicillium sp. and microbial transformation of citral by sporulated surface cultures method (SSCM) of Penicillium digitatum have been reported. The objective of this research was to study the pathway involved during biotransformation of citral by Penicillium sp. using two methods. The culture preparation was done using different microbial methods and incubation periods to obtain Penicillium for citral biotransformation. The biotransformation products were identified by gas chromatography (GC) and gas chromatography/mass spectroscopy (GC/MS). A comparison of the two methods showed that SSCM was more effective, its major products were thymol (21.5 %), geranial (18.6 %) and nerol (13.7 %). LM produced only one compound — thymol — with a low efficiency.

Biotransformation of thymol by hairy roots of transgenic Polygonum multiflorum

OBJECTIVE

The exogenous substrate, thymol, was firstly biotransformed by using suspension hairy roots of transgenic Polygonum multflorum, and its biotransformed situation was also investigated.

METHODS

After five days co-cultivated period, the transformed product was isolated by Thin Layer Chromatograph and Column Chromatograph, with the structure elucidated by physic-chemical methods and spectra data. Meanwhile, the time course of biotransformation (T-C) for thymol was also measured by HPLC to illuminate its bio-transformed situation.

RESULTS

The glycosylated product, namely DMP, was isolated and purified, which structure was determined as 5-methyl-2-(1-methylethyl) phenyl- beta-D-glucopyranoside. And the distribution of DMP in the medium or culture was varied in different co-cultivated periods, and for five days co-cultivated period, it mainly existed in the medium.

CONCLUSION

The hairy roots of Polygonum multiflorum were able to convert the aromatic exogenous substrate, thymol, into its glycoside. Furthermore, the time course indicated the relationship between DMP and co-cultivated period.

Evaluation of the environmental fate of thymol and phenethyl propionate in the laboratory

BACKGROUND

The natural monoterpenoid pesticides thymol and phenethyl propionate (PEP) are used indoors and outdoors, but their fate in the environment has not been reported. In order better to understand their impact on the environment, water metabolism and soil metabolism studies were conducted with thymol and PEP at a concentration of 10 microg g(-1) in water and in soil under laboratory conditions.

RESULTS

Dissipation half-lives of thymol and PEP were 16 and 5 days in water and 5 and 4 days in soil. 2-Phenylethanol and 2-(4-hydroxyphenyl)ethanol were detected as primary degradation products of PEP. Over time, a considerable volatilization loss of thymol, but not of phenethyl propionate, was found in the 1 month study under the experimental conditions used. Less than 6% of thymol and PEP were detected as bound residues, and less than 3% were mineralized during the 30 day study.

CONCLUSION

In order to maximize the pesticidal effect, more attention should be paid to the temperature for thymol than for PEP when they are being applied, owing to the high volatility of the former. Thymol and PEP pose low risks to the ecosystem because of their rapid dissipation and low bound residues in the environment.

Thymol and carvacrol production from leaves of wild Palestinian Majorana syriaca

Majorana syriaca (Zaatar in Arabic), belonging to the mint family, Labiates, is cultivated widely and grows wild in the mountains of Palestine between the months April to August. In order to determine the secondary metabolites from wild leaves of Palestinian M. syriaca, comparative analysis by static headspace (HS) and steam distillation (SD) GC-MS was used. Among the samples examined, the major constituents identified varied greatly throughout the different harvesting periods. Headspace revealed major volatiles and semi-volatiles of alpha-pinene, beta-myrecene, o-cymene, p-cymene, gamma-terpinene, thymol, and carvacrol. We found that the most abundant monoterpenes, i.e. gamma-terpinene and p-cymene were decreased in the month of May since they are the biogenetic precursors (via enzymic hydroxylation) of the phenolic terpenes, thymol and carvacrol. The harvesting time, location and the thyme type (i.e., wild) affects the yield of essential oils as reflected by normal steam distillation.

Growth and parameters of microflora in intestinal and faecal samples of piglets due to application of a phytogenic feed additive

A commercial phytogenic feed additive (PFA), containing the fructopolysaccharide inulin, an essential oil mix (carvacrol, thymol), chestnut meal (tannins) and cellulose powder as carrier substance, was examined for effects on growth and faecal and intestinal microflora of piglets. Two experiments (35 days) were conducted, each with 40 male castrated weaned piglets. In experiment 1, graded levels of the PFA were supplied (A1: control; B1: 0.05% PFA; C1: 0.1% PFA; D1: 0.15% PFA) in diets based on wheat, barley, soybean meal and fish meal with lysine as the limiting amino acid. In experiment 2, a similar diet with 0.1% of the PFA (A2: control; B2: 0.1% PFA; C2: +0.35% lysine; D2: 0.1% PFA + 0.35% lysine) and lysine supplementation was utilized. During experiment 1, no significant effect of the PFA on growth, feed intake and feed conversion rate was observed (p > 0.05). Lysine supplementation in experiment 2 improved growth performance significantly, but no significant effect of the PFA was detected. Microbial counts in faeces (aerobes, Gram negatives, anaerobes and lactobacilli) during the first and fifth week did not indicate any significant PFA effect (p > 0.05). In addition, microflora in intestinal samples was not significantly modified by supplementing the PFA (p > 0.05). Lysine supplementation indicated lysine as limiting amino acid in the basal diet, but did not influence the microbial counts in faeces and small intestine respectively.

No impact of a phytogenic feed additive on digestion and unspecific immune reaction in piglets

Two 35 day experiments were conducted to examine the influence of a commercial phytogenic feed additive (PFA) on nutrient digestibility and unspecific immune reaction of piglets in the post-weaning period. The PFA composition was inulin, an essential oil mix (carvacrol and thymol), chestnut meal (tannins), and cellulose powder as carrier substance. In each experiment, immediately after weaning 40 male castrated piglets were divided into four experimental groups (n = 10). Diets were based on wheat, barley, soy bean meal and fishmeal using lysine as the first limiting amino acid. In experiment 1, graded levels of the PFA were supplied (A: control; B: 0.05% PFA; C: 0.1% PFA; D: 0.15% PFA). Experiment 2 utilized equal diets with 0.1% of the PFA, but different lysine supply (A: control; B: 0.1% PFA; C: +0.35% lysine; D: 0.1% PFA + 0.35% lysine). At the end of the experimental period, acute phase proteins (APPs) haptoglobin and C-reactive protein were examined in individual blood plasma samples. Following each growth study, 16 animals (n = 4) were taken for sampling of ileal chyme and assessing of praecaecal digestibility of protein and amino acids. In addition, digesta samples of the duodenum and the total pancreatic tissue were utilized for determining the enzyme activity of alpha-amylase and trypsin. APP, praecaecal digestibility and enzyme activities did not significantly respond to the PFA supplementaion in diets.

Biotransformation of thymol, carvacrol, and eugenol by cultured cells of Eucalyptus perriniana

The biotransformations of aroma compounds of spices, such as thymol (1), carvacrol (2), and eugenol (3), were investigated using cultured plant cells of Eucalyptus perriniana. Besides a beta-glucoside product (4, 3%), a biotransformation product, i.e., 5-methyl-2-(1-methylethyl)phenyl 6-O-(beta-d-glucopyranosyl)-beta-d-glucopyranoside (5, beta-gentiobioside, 87%), was isolated from the suspension cells after the five-day incubation of 1. On administration of 2, a beta-glucoside (6, 5%) and a beta-gentiobioside, i.e., 2-methyl-5-(1-methylethyl)phenyl 6-O-(beta-d-glucopyranosyl)-beta-d-glucopyranoside (7, 56%), were produced. Furthermore, E. perriniana cells also converted 3 into the corresponding beta-glucoside (8, 7%) and beta-gentiobioside (9, 58%). The cultured cells of E. perriniana are able to convert these aroma compounds of spices into glycosides which are accumulated in the cells.

Odorant binding and conformational dynamics in the odorant-binding protein

In mammals, the olfactory epithelium secretes odorant-binding proteins (OBPs), which are lipocalins found freely dissolved in the mucus layer protecting the olfactory neurons. OBPs may act as passive transporters of predominantly hydrophobic odorant molecules across the aqueous mucus layer, or they may play a more active role in which the olfactory neuronal receptor recognizes the OBP-ligand complex. To better understand the molecular events accompanying the initial steps in the olfaction process, we have performed molecular dynamics studies of rat and pig OBPs with the odorant molecule thymol. These calculations provide an atomic level description of conformational changes and pathway intermediates that remain difficult to study directly. A series of eight independent molecular dynamics trajectories of rat OBP permitted the observation of a consensus pathway for ligand unbinding and the calculation of the potential of mean force (PMF) along this path. Titration microcalorimetry confirmed the specific binding of thymol to this protein with a strong hydrophobic component. In both rat and pig OBPs we observed lipocalin strand pair opening in the presence of ligand, consistent with potential roles of these proteins in olfactive receptor recognition.

Incorporation of thymol into corncob granules for reduction of odor and pathogens in feedlot cattle waste1,2

Confined animal feeding operations can be a source of odor emissions, global warming gases, water pollution, and food contamination. Laboratory studies have indicated that plant oils with antimicrobial activity can be used to control pathogens and odor emissions from cattle and swine wastes. However, these oils are aromatic and may volatilize when applied topically. Our objectives were to evaluate the volatility of thymol from a feedlot surface and the effectiveness of topically applying thyme oil (2.5% thymol), incorporated into corncob granules and added once per week, to control odor emissions and total coliforms in feedlot manure. In the first study, thymol either volatilized or was degraded within 28 d after topical application. In a second study, thyme oil (2.5% thymol) was incorporated into corncobs and applied to pen surfaces weekly. Manure samples from 6 locations in each pen were collected from 3 untreated and 3 thymol-corncob-treated pens (15 x 150 m; fifty 400-kg cattle/pen), 3 times per week for 8 wk. Samples were analyzed for thymol concentration, total VFA, branched-chain VFA, aromatic compounds, and the number of Escherichia coli and total coliform bacteria. Over the 8 wk, with the exception of wk 7, the desired thymol concentration of 15 to 20 micromol/g DM was maintained in the manure. Concentrations of VFA and branched chain-VFA increased over time in untreated and treated pens. However, the rate of VFA accumulation in treated pens (7.5 +/- 1.3 micromol.g DM(-1).wk(-1)) was less (P < 0.01) than the rate of accumulation in untreated pens (18.0 +/- 2.1 micromol.g DM(-1).wk(-1)). Likewise, the rate of branched-chain VFA accumulation in treated pens (0.31 +/- 0.04 micromol.g DM(-1).wk(-1)) was less (P < 0.01) than in untreated pens (0.55 +/- 0.06 micromol.g DM(-1).wk(1)). The concentrations of E. coli in treated pens (2.9 +/- 1.2 x 10(5) cfu.g DM(-1)) were 91% less (P < 0.04) than in untreated pens (31.1 +/- 4.0 x 10(5) cfu.g DM(-1)). Similarly, concentrations of coliforms in treated pens (3.7 +/- 1.3 x 10(5) cfu.g DM(-1)) were 89% less (P < 0.04) than those of untreated pens (35.3 +/- 4.2 x 10(5) cfu.g DM(-1)). These results indicate that odor emissions and total coliforms can be reduced in feedlot manure with a once per week application of thymol incorporated in a granular form. However, corncobs are bulky, and other granular carriers with a greater carrying capacity for thyme oil should be explored.

A Simple and Rapid in situ Preconcentration Method for Trace Ammonia Nitrogen in Environmental Water Samples Using a Solid-Phase Extraction Followed by Spectrophotometric Determination

A simple and rapid in situ preconcentration method for the spectrophotometric determination of trace ammonia nitrogen in environmental water samples has been developed based on solid-phase extraction using a small column packed with octadecyl group-bonded silica gel (Sep-Pak C18 cartridge). A water sample was taken into a graduated syringe for easy and simple operation and prevention of contamination immediately after sample collection. Ammonia in the sample was reacted with hypochlorite and thymol to be converted into indothymol blue; then the formed indothymol blue was collected as an ion pair between indothymol blue and tetrabutylammonium ion on a Sep-Pak C18 cartridge. The indothymol blue on the cartridge was stable for 4 days. The retained indothymol blue was easily eluted with a mixture of methanol and 0.01 mol/l sodium hydroxide solution. The color intensity due to the indothymol blue was spectrophotometrically measured at 725 nm. The proposed method was successfully applied to environmental water samples such as river water.

Metabolism of thymol and trans-anethole in larvae of Spodoptera litura and Trichoplusia ni (Lepidoptera: Noctuidae)

Metabolism of the monoterpenoid thymol and the phenylpropanoid trans-anethole, both constituents of essential oils, was investigated following topical and oral administration of the compounds to the tobacco cutworm (Spodoptera litura) and the cabbage looper (Trichoplusia ni). In both species and irrespective of route, administration of thymol resulted in the excretion of its 3-O-beta-glucoside, whereas trans-anethole was hydroxylated on the side chain methyl group. Both metabolites were isolated and their structures elucidated by interpretation of their mass and NMR spectra. Previous experiments indicated that trans-anethole synergized the toxicity of thymol in S. litura, but analyses of feces indicated that metabolism of thymol was not significantly suppressed when the two compounds were orally coadministered to T. ni larvae.

Thymol and carvacrol binding to DNA: model for DRUG-DNA interaction

Thymol and carvacrol can bind to major and minor grooves of B-DNA. The aim of this study was to examine the interaction of calf thymus DNA with thymol and carvacrol in aqueous solution and physiological pH with thymol/DNA and carvacrol/DNA (phosphate) molar ratios of 1/20, 1/10, 1/5, and 1/1. Fourier transform infrared and UV-visible difference spectroscopy were used to determine the thymol and carvacrol binding mode, binding constant, sequence selectivity, DNA secondary structure, and structural variations of thymol/DNA and carvacrol/DNA complexes in aqueous solution. Spectroscopic evidence showed that the thymol and carvacrol interaction occurred mainly through H-bonding of the thymol and carvacrol OH group to the guanine N7, cytosine N3, and backbone phosphate group with overall binding constant of K(thymol-DNA) = 2.43 x 10(3) M(-1), K(carvacrol-DNA) = 1.55 x 10(3) M(-1). In thymol and carvacrol-DNA complexes, DNA remains in the B-family structure.

Non-invasive localization of thymol accumulation in Carum copticum (Apiaceae) fruits by chemical shift selective magnetic resonance imaging

Magnetic resonance imaging was used to localize the site of essential oil accumulation in fruit of Carum copticum L. (Apiaceae). A chemical shift method is described that utilized the spectral properties of the aromatic monoterpene thymol, the major component of the essential oil, to image thymol selectively. The presence of essential oil secretory structures in the fruit and an essential oil containing a high proportion of thymol were confirmed with optical microscopy and gas chromatography-mass spectrometry, respectively. Selective imaging of whole C. copticum fruits showed that thymol accumulation was localized to the secretory structures (canals) situated in the fruit wall. The technique was considered non-invasive as the seeds used in the imaging experiments remained intact and viable.

[Comparative analysis of the effects of alcoholism and opium addiction on liver function]

Groups of patients suffering alcoholism and narcomania were examined for the effect of intoxication on the blood serum enzymes of mainly liver origin: alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), as well as on thymol test. It has been shown that in patients with the first stage of alcoholism one could observe only functional disturbances in the liver: the increase of ADH activity which evidences for the induction of its synthesis. In patients with the first stage of opium narcomania one can record total hyperenzymenia, decrease of de-Rimis coefficient at the expense of more considerable increase of ALT activity than that of AST, as well as the sharp increase of thymol test--these are the signs of destructive and metabolic disturbances in the liver. In patients with the second stage of alcoholism one can observe the decrease of ALDH activity under the increase of ADH, AST, ALT activity and high thymol test-these are the signs of toxical hepatitis. Destructive and metabolic changes increase in the liver in the patients with the second stage of narcomania.

[Dopamine content in blood and activity of alcohol-transforming enzymes in alcoholism]

An increase of alcohol dehydrogenase activity is observed in patients with chronic alcoholism at the first stage of the disease under normal indices of activity of aldehyde dehydrogenase, aspartate- and alanine aminotransferase and thymol sample that evidences for the induction of alcohol dehydrogenase synthesis in the liver. At the second stage of alcoholism the activity of alcohol dehydrogenase, aspartate- and alanine aminotransferase, the index of thymol sample increase while activity of aldehyde dehydrogenase decreases that indicates to organic destructive changes in the liver. At the third stage of alcoholism one can observe the decrease in activity of alcohol dehydrogenase, aldehyde dehydrogenase and alanine aminotransferase relative to activity of these enzymes at the second stage, that can evidence for the increase of the possibility of the processes of synthesis of the liver. The correlation of alcohol dehydrogenase activity to that of aldehyde dehydrogenase in the process of formation and development of alcoholism is shifted towards the progressive accumulation of acetaldehyde. Parallel increase of dopamine concentration in blood creates conditions for formation of morphine-like alcaloides--products of condensation of acetaldehide with dopamine.

Stimulation of guinea pig neutrophil superoxide anion-producing system with thymol

Thymol stimulated O2- production in guinea pig neutrophils. O2- production occurred about 30 sec after the addition of thymol, and its rate was independent of extracellular Ca2+. Thymol-induced activity was inhibited by trifluoperazine (TFP), an inhibitor of protein kinase c, and its IC50 was less than that for 12-O-tetradecanoyl phorbol 13-acetate (TPA) induced activity. After complete activation, O2- production was reversed by addition of TFP or by washing out and resuspending in a stimuli-free medium. The responsiveness of the thymol-pulsed cells to another stimulus, TPA, was somewhat more than resting cells, but the responsiveness of the former cells to thymol was about half that of the latter cells. The ATP level of cells was reduced to one half its initial value during activation by thymol. These data suggest that the magnitude of thymol-induced O2- production in neutrophils is dependent on the initial density of the binding sites of the cells with thymol and the initial intracellular ATP concentration.

Metabolism in rats of p-cymene derivatives: carvacrol and thymol

The metabolism of carvacrol and thymol in rats was studied using gas chromatographic-mass spectrometric methods. The urinary excretion of metabolites was rapid. Only very small amounts were excreted after 24 hrs. Although large quantities of carvacrol and, especially, thymol were excreted unchanged (or as their glucuronide and sulphate conjugates), extensive oxidation of the methyl and isopropyl groups also occurred. This resulted in the formation of derivatives of benzyl alcohol and 2-phenylpropanol and their corresponding carboxylic acids. In contrast, ring hydroxylation of the two phenols was a minor reaction.

On the metabolic detoxication of thymol in rabbit and man

The metabolic detoxication of thymol was investigated in rabbit and man. Thymol glucuronide which the aglycone is intact, was isolated from thymol medicated rabbit urine and identified as a acetyl derivative of methyl glucuronate. The hydroxylated product of thymol, thymohydroquinone, was recognized in a small amount in thymol medicated human urine. It was presumed that thymohydroquinone is excreted as ethereal sulfuric acid conjugate in man.

On the metabolic detoxication of 4-iodothymol in man

The detoxication of 4-iodothymol was investigated in man. A new metabolite was isolated as a crystalline derivative from 4-iodothymol medicated urine and identified as 4-iodothymol glucuronide as a methyl acetyl derivative. The deiodinated metabolite of 4-iodothymol, thymoquinone, was also recognized in a very small amount in 4-iodothymol medicated urine.

The metabolism of thymol by a Pseudomonas

1. Pseudomonas putida when grown with thymol contained a meta-fission dioxygenase, which required ferrous ions and readily cleaved the benzene nucleus of catechols between adjacent carbon atoms bearing hydroxyl and isopropyl groups. 2. 3-Hydroxythymo-1,4-quinone was excreted towards the end of exponential growth and later was slowly metabolized. This compound was oxidized by partially purified extracts only when NADH was supplied; the substrate for the dioxygenase appeared to be 3-hydroxythymo-1,4-quinol, which was readily and non-enzymically oxidized to the quinone. 3. 2-Oxobutyrate (0.9 mole) was formed from 1 mole of 3-hydroxythymo-1,4-quinone with the consumption of 1 mole of oxygen; acetate, isobutyrate and 2-hydroxybutyrate (which arose from the enzymic reduction of 2-oxobutyrate) were also formed. 4. These products, which were produced only when the catechol substrate contained a third hydroxyl group, appeared to result from the enzymic hydrolysis of the ring-fission product.