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Thymol is a famous plant-derived compound that has been widely used in pharmacy due to its antioxidant and antimicrobial properties. However, the modulation of intrinsic plant physiology by thymol remains unclear. It is a significant challenge to confer plant tolerance to Cd (cadmium) stress. In the present study physiological, histochemical, and biochemical methods were applied to investigate thymol-induced Cd tolerance in tobacco ( Nicotiana tabacum ) seedlings. Thymol was able to alleviate Cd-induced growth inhibition of tobacco seedlings in both dose- and time-dependent manners. Both histochemical detection and in-tube assays suggested that thymol treatment blocked Cd-induced over-generation of reactive oxygen species (ROS), lipid peroxidation, and loss of membrane integrity in both leaves and roots. Thymol decreased Cd-induced cell death that was indicated in vivo by propidium iodide (PI) and trypan blue, respectively. Thymol stimulated glutathione (GSH) biosynthesis by upregulating the expression of γ- glutamylcysteine synthetase 1 ( GSH1 ) in Cd-treated seedlings, which may contribute to the alleviation of Cd-induced oxidative injury. In situ fluorescent detection of intracellular Cd 2+ revealed that thymol significantly decreased free Cd 2+ in roots, which could be explained by the thymol-stimulated GSH biosynthesis and upregulation of the expression of phyochelatin synthase 1 ( PCS1 ). Taken together, these results suggested that thymol has great potential to trigger plant resistant responses to combat heavy metal toxicity, which may help our understanding of the mechanism for thymol-modulated cell metabolic pathways in response to environmental stimuli.

Thymol is a natural plant-derived compound that has been widely used in pharmaceutical and food preservation applications. However, the antifungal mechanism for thymol against phytopathogens remains unclear. In this study, we identified the antifungal action of thymol against Fusarium graminearum, an economically important phytopathogen showing severe resistance to traditional chemical fungicides. The sensitivity of thymol on different F. graminearum isolates was screened. The hyphal growth, as well as conidial production and germination, were quantified under thymol treatment. Histochemical, microscopic, and biochemical approaches were applied to investigate thymol-induced cell membrane damage. The average EC50 value of thymol for 59 F. graminearum isolates was 26.3 μg·mL(-1). Thymol strongly inhibited conidial production and hyphal growth. Thymol-induced cell membrane damage was indicated by propidium iodide (PI) staining, morphological observation, relative conductivity, and glycerol measurement. Thymol induced a significant increase in malondialdehyde (MDA) concentration and a remarkable decrease in ergosterol content. Taken together, thymol showed potential antifungal activity against F. graminearum due to the cell membrane damage originating from lipid peroxidation and the disturbance of ergosterol biosynthesis. These results not only shed new light on the antifungal mechanism of thymol, but also imply a promising alternative for the control of Fusarium head blight (FHB) disease caused by F. graminearum.

Aspergillus flavus is a well-known pathogenic fungus for both crops and human beings. The acquisition of resistance to azoles by A. flavus is leading to more failures occurring in the prevention of infection by A. flavus. In this study, we found that thymol, one of the major chemical constituents of the essential oil of Monarda punctate, had efficient fungicidal activity against A. flavus and led to sporular lysis. Further studies indicated that thymol treatment induced the generation of both ROS and NO in spores, whereas NO accumulation was far later than ROS accumulation in response to thymol. By blocking ROS production with the inhibitors of NADPH oxidase, NO generation was also significantly inhibited in the presence of thymol, which indicated that ROS induced NO generation in A. flavus in response to thymol treatment. Moreover, the removal of either ROS or NO attenuated lysis and death of spores exposed to thymol. The addition of SNP (exogenous NO donor) eliminated the protective effects of the inhibitors of NADPH oxidase on thymol-induced lysis and death of spores. Taken together, it could be concluded that ROS is involved in spore death induced by thymol via the induction of NO.

Thymol is a plant-derived natural compound with antimicrobial activity. However, we have little knowledge about the application of thymol in agriculture. One of the limitations is the high volatility and low aqueous solubility of thymol. Tomato gray mold caused by Botrytis cinerea is one of the most devastating postharvest diseases. In this study, we prepared a nano-emulsion of thymol (named as Nano-Thy) to form a stable O/W (oil in water) microemulsion. In vitro experiments showed that Nano-Thy had antifungal activity against B. cinerea by inhibiting mycelial growth and spore germination. Nano-Thy induced ROS accumulation in mycelia, further leading to lipid peroxidation, cell membrane damage, and subsequent cell death. Nano-Thy significantly prevented the infection of B. cinerea on fresh tomato fruits. Finally, we discussed the mechanisms and their significance in controlling postharvest disease of fruit crops. [ABSTRACT FROM AUTHOR]

As a natural product isolated from thyme oil in thyme, thymol (2‐isopropyl‐5‐methylphenol) harbors antiviral, antioxidant, and other properties, and thus could be potentially used for the treatment of various diseases. However, the function of thymol has not been comprehensively studied. Here, we applied an inverse molecular docking approach to identify unappreciated functions of thymol. Potential targets of thymol in humans were identified by the server of DRAR‐CPI, and targets of interest were then assessed by GO and KEGG pathway analysis. Subsequently, homologous proteins of these targets in Caenorhabditis elegans were identified by Blast tool, and their three‐dimensional structures were achieved using Swiss‐Model workspace. Interaction between thymol and the targeted proteins in worms was verified using AutoDock 4.0. Analyses of the targets revealed that thymol could be potentially involved in the glycolysis/gluconeogenesis and fatty acid degradation pathways. To verify the activity of thymol on lipid deposition in vivo, the C. elegans model was established. The lipid content of nematodes induced by high‐dose glucose was determined by Oil Red O and Nile Red staining, and gene expression was assessed by qRT‐PCR. The results showed that thymol might lead to the acceleration of β‐oxidation by upregulating cpt‐1, aco, fabp, and tph‐1, causing the descent of lipid content in nematodes. Our findings indicated that thymol could be potentially used for the treatment of chronic metabolic diseases associated with increased fatty acid deposition. [ABSTRACT FROM AUTHOR]