The tomato leafminer, Tuta absoluta (Meyrick) is a destructive pest of tomato, potato and other solanaceous crops of economic importance. One of the primary tools in its management is the use of conventional synthetic insecticides; however, this overreliance on synthetic insecticides quickly leads to the problem of insecticide resistance. In recent years, essential oils (EOs) of medicinal plants have received much attention as pest control chemical agents. If found, active compounds that are less persistent will be beneficial for both the environment and agricultural product consumers. In the current study, we studied the fumigant toxicity of EO of the Shirazi thyme, Zataria multiflora Boiss on the eggs, the second larval instars and adults. We analysed the composition of the EO by gas chromatography–mass spectrometry. The major component in the oil was thymol (33.52%). The EO showed strong adulticidal, larvicidal and ovicidal activity. Results show that by increasing the oil concentration, mortality will increase. By Probit analysis, the LC50 values for eggs, second larvae (inside leaf, outside leaf) and adults were 60.26, 4.44, 1.26 and 1.38 µl/L air, respectively. The EO of Z. multiflora may be suitable as a fumigant, because of its high volatility and safety.

Recent studies indicate that intestinal oxidative stress and microbiota imbalance is involved in weaning-induced intestinal dysfunction in piglets. We have investigated the effect of feeding a carvacrol–thymol blend supplemented diet on intestinal redox status, selected microbial populations and the intestinal barrier in weaning piglets. The piglets (weaned at 21 days of age) were randomly allocated to two groups with six pens per treatment and 10 piglets per pen. At weaning day (21 days of age), six piglets were sacrificed before weaning to serve as the preweaning group. The weaned group was fed with a basal diet, while the weaned-CB group was fed with the basal diet supplemented with 100 mg/kg carvacrol–thymol (1 : 1) blend for 14 days. On day 7 post-weaning, six piglets from each group were sacrificed to determine intestinal redox status, selected microbial populations, messenger RNA (mRNA) transcript levels of proinflammatory cytokines and biomarkers of intestinal barrier function. Weaning resulted in intestinal oxidative stress, indicated by the increased concentration of reactive oxygen species and thiobarbituric acid-reactive substances present in the intestine. Weaning also reduced the population of Lactobacillus genus and increased the populations of Enterococcus genus and Escherichia coli in the jejunum, and increased mRNA levels of tumor necrosis factor α (TNF-α), interleukin 1β and interleukin 6 (IL-6). In addition, decreased mRNA levels of zonula occludens and occludin in the jejunal mucosa and increased plasma diamine oxidase concentrations indicated that weaning induced dysfunction of the intestinal barrier. On day 7 post-weaning, supplementation with the carvacrol–thymol blend restored weaning-induced intestinal oxidative stress. Compared with the weaned group, the weaned-CB group had an increased population of Lactobacillus genus but reduced populations of Enterococcus genus and E. coli in the jejunum and decreased mRNA levels of TNF-α. The results indicated that weaning induced intestinal oxidative stress and dysfunction of the intestinal barrier. Dietary supplementation with 100 mg/kg carvacrol–thymol (1 : 1) decreased the intestinal oxidative stress and influenced selected microbial populations without changing the biomarkers of intestinal barrier in weaning piglets.

Thymol is the most common molecule in thyme and has been proposed as an oral alternative to antibiotics in the feed of pigs and broilers. The knowledge of the in vivo physiological effects of thymol on tissues is limited, particularly its impact on the gastric mucosa, where it is primarily absorbed when it is orally supplied. In this study, thymol (TH, 50 mg/ kg BW) or a placebo (CO) was introduced directly into the stomach of 8 weaned pigs that were slaughtered 12 h later and sampled for gastric oxyntic and pyloric mucosa. The analysis of whole transcript expression was performed using Affymetrix© Porcine Gene 1.1 ST array strips. Affymetrix Transcripts IDs were associated with 13 406 human gene names based on Sus scrofa Ensemble. Gene Set Enrichment Analysis was performed, comparing TH and CO pigs. For each gene set, the normalized enrichment score (NES) was defined as significant when the false discovery rate % was <25 and the P-value of NES was <0.05. In response to TH, 72 and 19 gene sets were significantly enriched in the oxyntic and pyloric mucosa, respectively. Several gene sets involved in mitosis and its regulation ranked near the top, primarily in the oxyntic mucosa; the gene set DIGESTION ranked first and ninth in the pyloric and oxyntic mucosa, respectively. Within this group, somatostatin (SST), SST receptors, peptide transporter 1 (SLC15A1) and calpain 9 (gastrointestinal tract-specific calpain) were the most strongly upregulated genes. Thymol reduced the enrichment of 120 and 59 gene sets in the oxyntic and pyloric mucosa, respectively. Several gene sets related to ion transport and channeling and aqueous pores across membranes, including short transient receptor potential (TRP) channel 4, potassium voltage-gated channel members 1 and 2, and ryanodine receptors 2 and 3, were less enriched. The downregulation of these genes sensitive to thymol in vitro could depend on the thymol dose and contact with the gastric tissues that causes an adaptive response with their reduced activation. Conversely, the activation of the TRPA1 gene (ranked 1072 and 128 among all the genes in the oxyntic and pyloric mucosa, respectively) indicates the involvement of another TRP-regulating cellular calcium storage. In conclusion, the stimulation of gastric proliferative activity and the control of digestive activity by thymol can influence positively gastric maturation and function in the weaned pigs. These properties should be considered in addition to thymol’s antimicrobial properties when supplementation of this molecule in feed is evaluated.

Background and objective: Thymol is a naturally occurring phenol derivative used in anaesthetic practice as a stabilizer and preservative of halothane, usually at a concentration of 0.01%. Although analgesic effects have long been described for thymol and its structural homologue menthol, a molecular basis for these effects is still lacking. We studied the blocking effects of thymol and menthol on voltage-activated sodium currents in vitro as possible molecular target sites.

Methods: Whole cell sodium inward currents via heterologously (HEK293 cells) expressed rat neuronal (rat type IIA) and human skeletal muscle (hSkM1) sodium channels were recorded in the absence and presence of definite concentrations of either thymol or menthol.

Results: When depolarizing pulses to 0 mV were started from a holding potential of-70 mV, halfmaximum blocking concentrations (IC50) for the skeletal muscle and the neuronal sodium channel were 104 and 149 µmol for thymol and 376 and 571 µmol for menthol. The blocking potency of both compounds increased at depolarized holding potentials with the fraction of inactivated channels. The estimated dissociation constant K d for thymol and menthol from the inactivated state was 22 and 106 µmol for the neuronal and 23 and 97 µmol for the skeletal muscle sodium channel, respectively.

Conclusions: The results suggest that antinociceptive and local anaesthetic effects of thymol and menthol might be mediated via blockade of voltage-operated sodium channels with the phenol derivative thymol being as potent as the local anaesthetic lidocaine.

Introduction. Sweet cherries are susceptible to postharvest decay. The use of synthetic fungicides is discouraged in postharvest handling because they can leave a residue and present a safety risk. Therefore, naturally occurring compounds have been considered as an alternative. Fumigation of short-chain organic acids and essential oils has shown promise in controlling fungal activities. This study reports their effects on sweet cherries. Materials and method. `Hedelfingen' sweet cherries (Prunus avium L.) were inoculated with conidia of Monilinia fructicola and Penicillium expansum, then fumigated with three levels of thymol or acetic acid for 10 min before cold storage. Results and discussion. After 13 d at 10°C, sweet cherries fumigated with 10 mg × L-1 of thymol significantly reduced brown rot from 21% to 12%, but had no effect on reducing blue mold rot. Fumigation with 6 or 10 mg × L-1 acetic acid significantly reduced blue mold rot from 16% to 2%, but had no effect on reducing brown rot. Fumigation did not have any effect on the firmness, total soluble solids and titratable acid of the sweet cherries. Fumigation with 2 or 6 mg × L-1 of thymol did not accelerate stem browning compared with the control, but fumigation with 10 mg Yen L-1 of thymol caused almost total stem browning. Fumigation with acetic acid showed no impact on discoloration of the stems. Conclusion. Thus, fumigation with acetic acid or thymol at low concentrations has a potential use for postharvest decay control without adverse effects on fruit quality.

The present study measured changes in antioxidant enzyme activity in, and the phospholipid fatty acid composition of the ageing rat brain and tested whether dietary supplementation with thyme oil or thymol could provide beneficial effects. There were significant declines in superoxide dismutase (EC 1.15.1.1) and glutathione peroxidase (EC 1.11.1.9) activities and the total antioxidant status in the untreated rats with age, while thyme-oil- and thymol-fed rats maintained significantly higher antioxidant enzyme activities and total antioxidant status. The proportions of 18: 2n−6, 20: 1n−9, 22: 4n−6 and 22: 5n−3 in the brain phospholipids resulting from all three dietary treatments were significantly higher in 28-month-old rats than in 7-month-old rats. Only 20: 1n−9 levels in 28-month-old thyme-oil- and thymol-treated rats were significantly higher than in the age-matched control. The proportion of 22: 6n−3 in brain phospholipids, which declined with age in control rats, was also significantly higher in rats given either supplement. This latter finding is particularly important as optimum levels of 22: 6n−3 are required for normal brain function. These results highlight the potential benefit of thyme oil as a dietary antioxidant.