The protective action of thymol against carbon tetrachloride hepatotoxicity in mice

Protective effects of Lavandula stoechas and Thymus numidicus essential oils against deltamethrin-induced hematological and biochemical toxicity in female rabbits

Recent studies have shown that essential oils (EOs) extracted from medicinal and aromatic plants have herbicidal and/or insecticidal properties, helping to mitigate the toxicity experienced by living organisms exposed to pesticides. Moreover, the primary compounds isolated from these EOs also have the potential to reduce pesticide-induced damage. The present work aimed to evaluate the protective effects of Thymus numidicus (TNEO) and Lavandula stoechas (LSEO) against Deltamethrin-induced toxicity in female rabbits. The results obtained by GC/MS analysis showed that monoterpenes and oxygenated monoterpenes were the main components of the EOs extracted from the aerial parts of Thymus numidicus and Lavandula stoechas. The use of the pesticide Deltamethrin caused significant damage to the liver and kidneys (p < 0.05), together with blood disorders, signs of restlessness and tremors. However, females treated with TNEO showed better tolerance than the group treated with LSEO. The combination of both oils showed more pronounced protective effects. This suggests a potential synergistic effect in reducing deltamethrin-induced toxicity.

Protective effects of Lavandula stoechas and Thymus numidicus essential oils against deltamethrin-induced hematological and biochemical toxicity in female rabbits

Recent studies have shown that essential oils (EOs) extracted from medicinal and aromatic plants have herbicidal and/or insecticidal properties, helping to mitigate the toxicity experienced by living organisms exposed to pesticides. Moreover, the primary compounds isolated from these EOs also have the potential to reduce pesticide-induced damage. The present work aimed to evaluate the protective effects of Thymus numidicus (TNEO) and Lavandula stoechas (LSEO) against Deltamethrin-induced toxicity in female rabbits. The results obtained by GC/MS analysis showed that monoterpenes and oxygenated monoterpenes were the main components of the EOs extracted from the aerial parts of Thymus numidicus and Lavandula stoechas. The use of the pesticide Deltamethrin caused significant damage to the liver and kidneys (p < 0.05), together with blood disorders, signs of restlessness and tremors. However, females treated with TNEO showed better tolerance than the group treated with LSEO. The combination of both oils showed more pronounced protective effects. This suggests a potential synergistic effect in reducing deltamethrin-induced toxicity.

Thymol's modulation of cellular macromolecules, oxidative stress, DNA damage, and NF-kB/caspase-3 signaling in the liver of imidacloprid-exposed rats

We evaluated whether thymol (THY) (30 mg/kg b.wt) could relieve the adverse effects of the neonicotinoid insecticide imidacloprid (IMD) (22.5 mg/kg b.wt) on the liver in a 56-day oral experiment and the probable underlying mechanisms. THY significantly suppressed the IMD-associated increase in hepatic enzyme leakage. Besides, the IMD-induced dyslipidemia was considerably corrected by THY. Moreover, THY significantly repressed the IMD-induced hepatic oxidative stress, lipid peroxidation, DNA damage, and inflammation. Of note, the Feulgen, mercuric bromophenol blue, and PAS-stained hepatic tissue sections analysis declared that treatment with THY largely rescued the IMD-induced depletion of the DNA, total proteins, and polysaccharides. Moreover, THY treatment did not affect the NF-kB p65 immunoexpression but markedly downregulated the Caspase-3 in the hepatocytes of the THY+IMD-treated group than the IMD-treated group. Conclusively, THY could efficiently protect against IMD-induced hepatotoxicity, probably through protecting cellular macromolecules and antioxidant, antiapoptotic, and anti-inflammatory activities.

Thymol ameliorates ethanol-induced hepatotoxicity via regulating metabolism and autophagy

Alcoholic liver disease represents a serious threat to human health. In terms of safety and acceptability, thymol is widely used in or on foodstuffs to generate odour and taste. The present study aimed to investigate the therapeutic effect and mechanism of thymol against ethanol-induced injury in liver cells. Here we found that thymol is an effective agent for reducing ethanol-induced reactive oxygen species production in mouse liver cells. Thymol improves ethanol-induced lipid accumulation, and this corresponded to altered DGAT2 mRNA expression levels. Metabolomics data analysis showed that thymol alleviated ethanol-induced changes in the levels of thirty-four metabolites including nicotinic acid and l-arginine. By utilizing pathway enrichment analysis, altered metabolites in cells treated with ethanol and ethanol plus thymol were enriched in fourteen pathways including metabolic pathways and arginine and proline metabolism. We further confirmed the alleviation of overdose nitric oxide production in cells treated with ethanol plus thymol compared with that in ethanol-treated cells. It was interesting that up-regulated LC3-II/LC3-I ratio together with higher SQSTM1 protein abundance in ethanol-treated cells were attenuated by treatment with ethanol plus thymol. Thymol ameliorated ethanol-induced reduction of HSPA8 protein abundance. In addition, chloroquine-treated cells exhibited lower HSPA8 protein abundance compared with cells simulated with ethanol plus thymol. These data reveal that improving effect of thymol on ethanol-induced metabolic alteration is related to autophagic flux restoration. Our findings indicate that thymol is an attractive option for treating ethanol-induced liver damage.

Thyme Oil and Thymol Counter Doxorubicin-Induced Hepatotoxicity via Modulation of Inflammation, Apoptosis, and Oxidative Stress

Doxorubicin (DOX) is an effective anticancer agent with a wide spectrum of activities. However, it has many adverse effects on various organs especially on the liver. Thymol, one of the major components of thyme oil, has biological properties that include anti-inflammatory and antioxidant activities. Thus, this study was designed to examine thyme oil and thymol for their ability to prevent doxorubicin-induced hepatotoxicity in Wistar rats. Hepatotoxicity was induced by an intraperitoneal injection of doxorubicin, at a dose of 2 mg/kg bw/week, for seven weeks. Doxorubicin-injected rats were supplemented with thyme oil and thymol at doses 250 and 100 mg/kg bw, respectively, four times/week by oral gavage for the same period. Treatment of rats with thyme oil and thymol reversed the high serum activities of AST, ALT, and ALP and total bilirubin, AFP, and CA19.9 levels, caused by doxorubicin. Thyme oil and thymol also reduced the high levels of TNF-α and the decreased levels of both albumin and IL-4. These agents ameliorated doxorubicin-induced elevation in hepatic lipid peroxidation and associated reduction in GSH content and GST and GPx activities. Further, the supplementation with thyme oil and thymol significantly augmented mRNA expression of the level of antiapoptotic protein Bcl-2 and significantly downregulated nuclear and cytoplasmic levels of the hepatic apoptotic mediator p53. Thus, thyme oil and thymol successfully counteracted doxorubicin-induced experimental hepatotoxicity via their anti-inflammatory, antioxidant, and antiapoptotic properties.

Morita-Baylis-Hillman adducts derived from thymol: synthesis, in silico studies and biological activity against Giardia lamblia

Giardiasis is a neglected disease, and there is a need for new molecules with less side effects and better activity against resistant strains. This work describes the evaluation of the giardicidal activity of thymol derivatives produced from the Morita-Baylis-Hillman reaction. Thymol acrylate was reacted with different aromatic aldehydes, using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalyst. Eleven adducts (8 of them unpublished) with yields between 58 and 80% were obtained from this reaction, which were adequately characterized. The in silico prediction showed theoretical bioavailability after oral administration as well as antiparasitic activity against Giardia lamblia. Compound 4 showed better biological activity against G. lamblia. In addition to presenting antigiardial activity 24 times better than thymol, this MBHA was obtained in a short reaction time (3 h) with a yield (80%) superior to the other investigated molecules. The molecule was more active than the precursors (thymol and MBHA 12) and did not show cytotoxicity against HEK-293 or HT-29 cells. In conclusion, this study presents a new class of drugs with better antigiardial activity in relation to thymol, acting as a basis for the synthesis of new bioactive molecules. Molecular hybridization technique combined with the Morita-Baylis-Hillman reaction provided new thymol derivatives with giardicidal activity superior to the precursor molecules.

Hepatoprotective Essential Oils: A Review

Objectives

Several toxins and molecules are able to damage the liver, causing the hepato-toxicity. This disorder can be protected naturally, by some essential oils obtained from different plants. In this review we are cited some of these compounds that have been tested by their hepatoprotective effect.

Methods

We reviewed 83 articles published between 1981 and 2018 in English via three databases Sciencedirect, Springer and PubMed. So, we have used the keywords Hepatoprotective effect, liver disease, plants and essential oils.

Results and conclusion

In this work, we classified the plants; contain the essential oils, in alphabetical order as a table containing the scientific, family names, information plants, the experimental assay and the results obtained from the hepatoprotective studies. We have described 27 species belonging to 12 families Lamiaceae (7 species), Asteraceae (6 species), Umbellifereae (3 species), Apiaceae (3 species) are the main families which enclose the species that was studied. The study also includes the major compounds isolated from some of these essential oils. The most of those compounds belong to terpene class essentially cineol, carvacrol and thymol. Thus, the different essential oils that have been cited in this review were shown that have an antioxidant activity.

Cardioprotective effect of thymol against adrenaline-induced myocardial injury in rats

Cardiovascular disease represents a vital global disease burden. This study aims to assess the possible cardioprotective effect of thymol against adrenaline-induced myocardial injury (MI) in rats. Furthermore the effect of thymol on cardiac function biomarkers, electrocardiogram (ECG) alterations, oxidative stress, inflammation, apoptosis and histopathological changes was assessed. MI was induced by adrenaline (2 mg/kg, s.c.) injected as a single dose for 2 consecutive days (24 h apart). Normal and control groups received the vehicle for 21 consecutive days. The other 3 groups were orally administered thymol (15, 30, 60 mg/kg) for 21 consecutive days and on day 22, adrenaline was injected as a single dose for 2 consecutive days. Then ECG examination, biochemical, histopathological, immunohistochemical analyses were carried out. Thymol reversed adrenaline-induced reduction of heart rate, prolongation of RR interval and elevation of ST interval. Thymol pretreatment significantly reduced serum aspartate dehydrogenase (AST), lactate dehydrogenase (LDH), and creatine kinase (CK) levels in MI rats. Oral pretreatment with thymol increased reduced glutathione (GSH), reduced malondialdehyde (MDA), nuclear factor-kappa B (NF-κB), and interleukin-1β (IL-1β) cardiac contents in MI rats. Additionally, thymol administration significantly decreased protein expression of caspase-3, increased Bcl-2 protein expression in cardiac tissue and ameliorated histopathological changes. This study reveals that thymol exerted cardioprotective effect against adrenaline-induced MI in rats evidenced by improving cardiac function, attenuating ECG and histopathological changes which may be partly mediated through its anti-oxidant, anti-inflammatory and anti-apoptotic effect.

Gastroprotective effects of oleuropein and thymol on indomethacin-induced gastric ulcer in Sprague-Dawley rats

Ethnopharmacological studies demonstrated that thymol (Thym) and oleuropein (Ole) have therapeutic potential for gastric ulcers. The molecular mechanism underlying the gastroprotective effects of these compounds have not been elucidated yet especially for their individual and combination use at high dose. Therefore, this study was conducted to explore their gastroprotective mechanisms on indomethacin (Indo)-induced gastric ulcer model. Ole (50,100, 250, and 500 mg/kg) and Thym (50,100, 200, and 500 mg/kg) were orally administered to the rats 10 min before the induction of ulcer with Indo. The combination of 500 mg/kg doses of Ole and Thym were applied. The gastric mucosa was evaluated histopathologically. Moreover, TAC/TOS, tumor necrosis factor-alpha (TNF-α), prostaglandin E₂ (PGE₂), endothelial nitric oxide synthase (eNOS), and caspase-3 levels were assessed by ELISA and the caspase-3 and TNF-α expressions were quantified by qRT-PCR. Indo-induced histopathological changes while Ole and Thym pretreatment prevented these effects. Unlike the 500 mg/kg dose of Ole treatment, the 500 mg/kg dose of Thym administration enhanced these damages. The decreased TAC, PGE₂ levels and increased TOS, eNOS, TNF-α, caspase-3 levels were obtained in Indo group. However, these changes were reversed by Ole and Thym groups except the 500 mg/kg dose of Thym and the combination treatment groups. Similar trends were observed in the caspase-3 and TNF-α expression levels. These results demonstrated that enhanced inflammation, oxidant/antioxidant imbalance, and apoptotic activities were occurred in Indo, 500 mg/kg dose of Thym and the combination treatment groups while not in the other groups. The findings demonstrated the gastroprotective ability of Ole and low doses of Thym in gastric ulcer models.

Comparative transcriptome analysis to identify putative genes involved in thymol biosynthesis pathway in medicinal plant Trachyspermum ammi L

Thymol, as a dietary monoterpene, is a phenol derivative of cymene, which is the major component of the essential oil of Trachyspermum ammi (L.). It shows multiple biological activities: antifungal, antibacterial, antivirus and anti-inflammatory. T. ammi, commonly known as ajowan, belongs to Apiaceae and is an important medicinal seed spice. To identify the putative genes involved in thymol and other monoterpene biosynthesis, we provided transcriptomes of four inflorescence tissues of two ajowan ecotypes, containing different thymol yield. This study has detected the genes encoding enzymes for the go-between stages of the terpenoid biosynthesis pathways. A large number of unigenes, differentially expressed between four inflorescence tissues of two ajowan ecotypes, was revealed by a transcriptome analysis. Furthermore, differentially expressed unigenes encoding dehydrogenases, transcription factors, and cytochrome P450s, which might be associated with terpenoid diversity in T. ammi, were identified. The sequencing data obtained in this study formed a valuable repository of genetic information for an understanding of the formation of the main constituents of ajowan essential oil and functional analysis of thymol-specific genes. Comparative transcriptome analysis led to the development of new resources for a functional breeding of ajowan.

Oxidative stress, eryptosis and anemia: a pivotal mechanistic nexus in systemic diseases

The average lifespan of circulating erythrocytes usually exceeds hundred days. Prior to that, however, erythrocytes may be exposed to oxidative stress in the circulation which could cause injury and trigger their suicidal death or eryptosis. Oxidative stress activates Ca²⁺ -permeable nonselective cation channels in the cell membrane, thus, stimulating Ca²⁺ entry and subsequent cell membrane scrambling resulting in phosphatidylserine exposure and activation of Ca²⁺ -sensitive K⁺ channels leading to K⁺ exit, hyperpolarization, Cl^- exit, and ultimately cell shrinkage due to loss of KCl and osmotically driven water. While the mechanistic link between oxidative stress and anemia remains ill-defined, several diseases such as diabetes, hepatic failure, malignancy, chronic kidney disease and inflammation have been identified to display both increased oxidative stress as well as eryptosis. Recent compelling evidence suggests that oxidative stress is an important perpetrator in accelerating erythrocyte loss in different systemic conditions and an underlying mechanism for anemia associated with these pathological states. In the present review, we discuss the role of oxidative stress in reducing erythrocyte survival and provide novel insights into the possible use of antioxidants as putative antieryptotic and antianemic agents in a variety of systemic diseases.

Hepatoprotective effect of thymol against subchronic toxicity of titanium dioxide nanoparticles: Biochemical and histological evidences

The study was aimed to investigate the protective action of thymol against nano titanium dioxide (nano-TiO₂) induced hepatotoxicity in rats. To achieve this purpose, the rats were divided into four groups (n = 6) including control, nano-TiO₂ (100 mg/kg), nano-TiO₂ + thymol (10 mg/kg) and nano-TiO₂ + thymol (30 mg/kg). Intragastric (IG) administration of nano-TiO₂ for 60 consecutive days caused widespread histological changes and significantly induced oxidative stress in the liver tissues as manifested by the rise in serum transaminase activities accompanied by marked decline of enzymatic (catalase, superoxide dismutase and glutathione peroxidase) and non-enzymatic (ferric reducing antioxidant power and glutathione) antioxidant levels, and rise of malondialdehyde levels in liver tissue. Pretreatment with thymol (IG) prior to nano-TiO₂ administration significantly ameliorated all of biochemical and histopathological alterations in a dose-dependent manner. In conclusion, thymol effectively protects against nano-TiO₂-induced hepatotoxicity in rats by its antioxidant properties.

Effects of thymol on amyloid-β-induced impairments in hippocampal synaptic plasticity in rats fed a high-fat diet

Obesity and a high-fat diet (HFD) are known to increase the incidence of Alzheimer's disease (AD). Oxidative stress, a major risk factor for AD, is increased with HFD consumption. Thymol (Thy) has antioxidant properties. Therefore, in the present study, we examined the protective and therapeutic effects of Thy on amyloid-β (Aβ)-induced impairments in the hippocampal synaptic plasticity of HFD-fed rats. In this study, 72 adult male Wistar rats were randomly assigned to 9 groups (n = 8 rats/group): Group 1 (control; standard diet); Group 2: Control + phosphate-buffered saline (PBS) + Oil (Thy vehicle); Group 3 (HFD + PBS); Group 4: (HFD + Aβ); Group 5: Control + PBS + Thy; Group 6: (HFD + Aβ + Oil); Group 7: Control + Aβ + Thy; Group 8: HFD + PBS + Thy; Group 9: (HFD + Aβ + Thy). After stereotaxic surgery, the field potentials were recorded after the implantation of the recording and stimulating electrodes in the dentate gyrus (DG) and perforant pathway, respectively. Following high-frequency stimulation, the long-term potentiation (LTP) of the population spike (PS) amplitude and the slope of the excitatory postsynaptic potentials (EPSPs) were measured in the DG. The HFD rats that received Aβ exhibited a significant decrease in their EPSP slope and PS amplitude as compared to the control group. In contrast, Thy administration in the HFD + Aβ rats reduced the decrease in the EPSP slope and PS amplitude. Thy decreased the Aβ-induced LTP impairments in HFD rats. The HFD significantly increased serum malondialdehyde levels and decreased total antioxidant capacity and total glutathione levels; whereas, Thy supplementation significantly reversed these parameters. Therefore, these results suggest that Thy, a natural antioxidant, can be therapeutic against high risk factors for AD, such as HFD.

Pharmacological Properties and Molecular Mechanisms of Thymol: Prospects for Its Therapeutic Potential and Pharmaceutical Development

Thymol, chemically known as 2-isopropyl-5-methylphenol is a colorless crystalline monoterpene phenol. It is one of the most important dietary constituents in thyme species. For centuries, it has been used in traditional medicine and has been shown to possess various pharmacological properties including antioxidant, free radical scavenging, anti-inflammatory, analgesic, antispasmodic, antibacterial, antifungal, antiseptic and antitumor activities. The present article presents a detailed review of the scientific literature which reveals the pharmacological properties of thymol and its multiple therapeutic actions against various cardiovascular, neurological, rheumatological, gastrointestinal, metabolic and malignant diseases at both biochemical and molecular levels. The noteworthy effects of thymol are largely attributed to its anti-inflammatory (via inhibiting recruitment of cytokines and chemokines), antioxidant (via scavenging of free radicals, enhancing the endogenous enzymatic and non-enzymatic antioxidants and chelation of metal ions), antihyperlipidemic (via increasing the levels of high density lipoprotein cholesterol and decreasing the levels of low density lipoprotein cholesterol and low density lipoprotein cholesterol in the circulation and membrane stabilization) (via maintaining ionic homeostasis) effects. This review presents an overview of the current in vitro and in vivo data supporting thymol's therapeutic activity and the challenges concerning its use for prevention and its therapeutic value as a dietary supplement or as a pharmacological agent or as an adjuvant along with current therapeutic agents for the treatment of various diseases. It is one of the potential candidates of natural origin that has shown promising therapeutic potential, pharmacological properties and molecular mechanisms as well as pharmacokinetic properties for the pharmaceutical development of thymol.

Evaluation of the bioactive extract of actinomyces isolated from the Egyptian environment against aflatoxin B1-induce cytotoxicity, genotoxicity and oxidative stress in the liver of rats

This study aimed to determine the bioactive compounds of actinomyces (ACT) isolated from the Egyptian environment (D-EGY) and to evaluate their protective activity against AFB₁ in female Sprague-Dawley rats. Six groups of animals were treated orally for 3 weeks included: C, the control group, T1, AFB₁-treated group (80 μg/kg b.w), T2 and T3, the groups received ACT extract at low (25 mg/kg b.w) or high (50 mg/kg b.w) doses, T4 and T5, the groups received AFB₁ plus the low or high dose of ACT extract. Blood, bone marrow and tissue samples were collected for different analyses and histological examination. The results revealed the identification of 40 components, representing 99.98%. Treatment with AFB₁ disturbs liver function parameters, oxidative stress markers, antioxidant gene expressions, DNA fragmentation and induced severe histological changes. ACT extract at the low or high doses did not induce significant changes in all the tested parameters or histological picture of the liver. Moreover, ACT extract succeeded to induce a significant protection against the toxicity of AFB₁. It could be concluded that the bioactive compounds in ACT are promise candidate for the development of food additive or drugs for the protection and treatment of liver disorders in the endemic area.

Final Report on the Safety Assessment of Sodium p -Chloro- m -Cresol, p -Chloro- m -Cresol, Chlorothymol, Mixed Cresols, m -Cresol, o -Cresol, p -Cresol, Isopropyl Cresols, Thymol, o -Cymen-5-ol, and Carvacrol1

Sodium p -Chloro- m -Cresol, p -Chloro- m -Cresol (PCMC), Mixed Cresols, m -Cresol, o -Cresol, p -Cresol, Isopropyl Cresols, Thymol, Chlorothymol, o -Cymen-5-ol, and Carvacrol are substituted phenols used as cosmetic biocides/preservatives and/or fragrance ingredients. Only PCMC, Thymol, and o -Cymen-5-ol are reported to be in current use, with the highest concentration of use at 0.5% for o -Cymen-5-ol in perfumes. The use of PCMC in cosmetics is restricted in Europe and Japan. Cresols can be absorbed through skin, the respiratory tract, and the digestive tract; metabolized by the liver; and excreted by the kidney as glucuronide and sulfate metabolites. Several of these cresols increase the dermal penetration of other agents, including azidothymidine. In acute oral toxicity studies, LD50 values were in the 200 to 5000 mg/kg day-1 range across several species. In short-term studies in rats and mice, an o -Cresol, m -Cresol, p -Cresol or m -Cresol/ p -Cresol mixture at 30,000 ppm in the diet produced increases in liver and kidney weights, deficits in liver function, bone marrow hypocellularity, irritation to the gastrointestinal tract and nasal epithelia, and atrophy of female reproductive organs. The no observed effect levels (NOEL) of o -Cresol was 240 mg/kg in mink and 778 mg/kg in ferrets in short-term feeding studies, with no significant dose-related toxicity (excluding body weight parameters). In mice, 0.5% p -Cresol, but neither m -Cresol nor o -Cresol, caused loss of pigmentation. Short-term and subchronic oral toxicity tests performed with various cresols using mice, rats, hamsters, and rabbits resulted in no observed adverse effect levels (NOAELs) for mice of 625 ppm and rats of 50 mg/kg day -1, although the NOEL was 2000 ppm ina chronic study using rats. In rabbits, 160 mg/kg PCMC was found to produce irritation and erythema, but no systemic effects. Hamsters dosed with 1.5% p -Cresol in diet for 20 weeks had a greater incidence of mild and moderate forestomach hyperplasia as compared to the control. Acute inhalation toxicity studies using rats yielded LC50 values ranging from > 20 mg/m3 for o -Cresol to > 583 mg/m3 for PCMC. No deaths were recorded in mice given o -Cresol at 50 mg/m3. Cats exposed (short-term) to 9 to 50 mg/m3 of o -Cresol developed inflammation and irritation of the upper respiratory tract, pulmonary edema, and hemorrhage and perivascular sclerosis in the lungs. Rats exposed (subchronic) to o -Cresol at 9 mg/m3 had changes in leukocytes, spinal cord smears, nervous activity, liver function, blood effects, clinical signs, and neurological effects. In guinea pigs, exposure to 9 mg/m3 produced changes in hemoglobin concentrations and electrocardiograms (EKGs). Rats exposed (subchronic) to 0.05 mg/m3 Mixed Cresols by inhalation exhibited central nervous system (CNS) excitation, denaturation of lung protein, and decreased weight gain. All cresols appear to be ocular irritants. Numerous sensitization studies have been reported and most positive reactions were seen with higher concentrations of Cresol ingredients. Developmental toxicity is seen in studies of m -Cresol, o -Cresol, and p -Cresol, but only at maternally toxic levels. In a reproductive toxicity study of a mixture of m -Cresol and p -Cresol using mice under a continuous breeding protocol, 1.0% caused minimal adult reproductive and significant postnatal toxicity in the presence of systemic maternal toxicity. The o -Cresol NOAEL was 0.2% for both reproductive and general toxicity in both generations. Cresol ingredients were generally nongenotoxic in bacterial, fruit fly, and mammalian cell assays. Thymol did not induce primary lung tumors in mice. No skin tumors were found in mice exposed dermally to m -Cresol, o -Cresol, or p -Cresol for 12 weeks. In the tryphan blue exclusion assay, antitumor effects were observed for Thymol and Carvacrol. Clinical patch testing with 2% PCMC may produce irritant reactions, particularly in people with multiple patch test reactions, that are misinterpreted as allergic responses. o -Cresol, p -Cresol, Thymol, Carvacrol, and o -Cymen-5-ol caused no dermal irritation at or above use concentrations. In two predictive patch tests, PCMC did not produce a sensitization reaction. Overall, these ingredients are not significant sensitizing or photosensitizing agents. The Cosmetic Ingredient Review (CIR) Expert Panel noted some of these ingredients may increase the penetration of other cosmetic ingredients and advised cosmetic formulators to take this into consideration. The CIR Expert Panel concluded that the toxic effects of these ingredients are observed at doses higher than would be available from cosmetics. A concentration limitation of 0.5% was chosen to ensure the absence of a chemical leukoderma effect. For p -Cresol and Mixed Cresols (which contain p -Cresol), the Panel considered that the available data are insufficient to support the safety of these two ingredients in cosmetics. Studies that would demonstrate no chemical leukoderma at concentrations of use of p -Cresol and Mixed Cresols, or would demonstrate a dose response from which a safe concentration could be derived, are needed.

The protective effects of carvacrol and thymol against paracetamol-induced toxicity on human hepatocellular carcinoma cell lines (HepG2)

Acetaminophen (APAP) overdose could induce liver damage and lead to acute liver failure. The treatment of APAP overdoses could be improved by new therapeutic strategies. Thymus spp., which has many beneficial effects and has been used in folk medicine, is one such potential strategy. In the present study, the hepatoprotective activity of the main constituents of Thymus spp., carvacrol and thymol, were evaluated in light of APAP-induced hepatotoxicity. We hoped to understand the hepatoprotective mechanism of these agents on the antioxidant system and pro-inflammatory cytokines in vitro. Dose-dependent effects of thymol and carvacrol (25, 50, and 100 µM) were tested on cultured HepG2 cells. N-Acetylcysteine (NAC) was tested as positive control. We showed that APAP inhibited HepG2 cell growth by inducing inflammation and oxidative stress. Incubating APAP-exposed HepG2 cells with carvacrol and thymol for 24 h ameliorated this inflammation and oxidative stress. We also evaluated alanine transaminase and lactate dehydrogenase levels of HepG2 cells. We found that thymol and carvacrol protected against APAP-induced toxicity in HepG2 cells by increasing antioxidant activity and reducing pro-inflammatory cytokines, such as tumor necrosis factor α and interleukin 1β. Taking together high-dose thymol and carvacrol treatment has an effect close to NAC treatment in APAP toxicity, but thymol has better treatment effect than carvacrol.

Panax ginseng extract modulates oxidative stress, DNA fragmentation and up-regulate gene expression in rats sub chronically treated with aflatoxin B1 and fumonisin B 1

Aflatoxins and fumonisins are important food-borne mycotoxins implicated in human health and have cytotoxic effects. The aims of the current study were to evaluate the protective role of Panax ginseng extract (PGE) against the synergistic effect of subchronic administration of aflatoxin B1 (AFB1) and fumonisin B1 (FB1) on DNA and gene expression in rat. Female Sprague-Dawley rats were divided into eight groups (ten rats/group) and treated for 12 weeks including the control group, the group having received AFB1 (80 µg/kg bw), the group having received FB1 (100 µg/kg bw), the group having received AFB1 plus FB1 and the groups having received PGE (20 mg/kg bw) alone or with AFB1 and/or FB1. At the end of experiment, liver and kidney were collected for the determination of DNA fragmentation, lipid peroxidation (LP), glutathione (GSH) contents and alterations in gene expression. The results indicated that these mycotoxins increased DNA fragmentation, LP and decreased GSH content in liver and kidney and down-regulated gene expression of antioxidants enzymes. The combined treatments with AFB1 and/or FB1 plus PGE suppressed DNA fragmentation only in the liver, normalized LP and increased GSH in the liver and kidney as well as up-regulated the expression of GPx, SOD1 and CAT mRNA. It could be concluded that AFB1 and FB1 have synergistic genotoxic effects. PGE induced protective effects against their oxidative stress and genotoxicity through its antioxidant properties.

Chitosan nanoparticles and quercetin modulate gene expression and prevent the genotoxicity of aflatoxin B1 in rat liver

The aims of the current study were to prepare chitosan nanoparticles (CNPs) and to evaluate its protective role alone or in combination with quercetin (Q) against AFB₁-induce cytotoxicity in rats. Male Sprague-Dawley rats were divided into 12 groups and treated orally for 4 weeks as follow: the control group, the group treated with AFB₁ (80 μg/kg b.w.) in corn oil, the groups treated with low (140 mg/kg b.w.) or high (280 mg/kg b.w.) dose of CNPs, the group treated with Q (50 mg/kg b.w.), the groups treated with Q plus the low or the high dose of CNPs and the groups treated with AFB₁ plus Q and/or CNPs at the two tested doses. The results also revealed that administration of AFB₁ resulted in a significant increase in serum cytokines, Procollagen III, Nitric Oxide, lipid peroxidation and DNA fragmentation accompanied with a significant decrease in GPx I and Cu–Zn SOD-mRNA gene expression. Q and/or CNPs at the two tested doses overcome these effects especially in the group treated with the high dose of CNPs plus Q. It could be concluded that CNPs is a promise candidate as drug delivery enhances the protective effect of Q against the cytogenetic effects of AFB₁ in high endemic areas.

Thymol and carvacrol prevent cisplatin-induced nephrotoxicity by abrogation of oxidative stress, inflammation, and apoptosis in rats

The aim of the present study is to assess the possible protective effects of thymol and carvacrol against cisplatin (CP)-induced nephrotoxicity. A single dose of CP {6 mg/kg, intraperitoneally (i.p.)} injected to male rats revealed significant increases in serum urea, creatinine, and tumor necrosis factor alpha levels. It also increased kidney contents of malondialdehyde and caspase-3 activity with significant reduction in serum albumin, kidney content of reduced glutathione as well as catalase, and superoxide dismutase activity as compared to that of the control group. In contrast, administration of thymol {20 mg/kg, orally (p.o.)} and/or carvacrol (15 mg/kg, p.o.) for 14 days before CP injection and for 7 days after CP administration restored the kidney function and examined oxidative stress parameters. In conclusion, thymol was more effective nephroprotective than carvacrol. Moreover, a combination of thymol and carvacrol had a synergistic nephroprotective effect that might be attributed to antioxidant, anti-inflammatory, and antiapoptotic activities.

The ameliorative effect of thymol against hydrocortisone-induced hepatic oxidative stress injury in adult male rats

The aim of the present study was to investigate whether hydrocortisone induces oxidative stress in hepatocytes and to evaluate the possible ameliorative effect of thymol against such hepatic injury. Twenty-four adult male rats were divided into control, thymol, hydrocortisone, and hydrocortisone+thymol groups. The 4 groups were treated daily for 15 days. Hydrocortisone significantly induced oxidative stress in the liver tissues, marked by increased serum levels of alanine transaminase (ALT), aspartate transaminase (AST), total oxidative capacity (TOC), and tumor necrosis factor-alpha (TNF-α) accompanied by marked decline of serum levels of total protein, albumin, and total antioxidant capacity (TAC). Also, marked elevation in the levels of the thiobarbituric acid reactive substances (TBARS) and TNF-α, beside significant decrease in the level of glutathione (GSH) in hepatic tissues were recorded. These biochemical alterations were accompanied by histopathological changes marked by destruction of the normal hepatic architecture, in addition to ultrastructural alterations represented by degenerative features covering almost all the cytoplasmic organelles of the hepatocytes. Supplementation of hydrocortisone-treated rats with thymol reversed most of the biochemical, histological, and ultrastructural alterations. The results of our study confirm that thymol has strong ameliorative effect against hydrocortisone-induced oxidative stress injury in hepatic tissues.

Protective effects of thymol against nephrotoxicity induced by cisplatin with using 99mTc-DMSA in mice

BACKGROUND

In this study, we investigated the protective effect of thymol as a natural compound against cisplatin-induced nephrotoxicity by quantitative renal 99mTc-DMSA uptake and compared its effect with histopathology in mice.

MATERIALS AND METHODS

Mice were divided into six groups as control, cisplatin (7.5 mg/kg, intraperitoneally), thymol+cisplatin (thymol; 50 and 150 mg/kg+cisplatin; 7.5 mg/kg) and thymol (50 and 150 mg/kg). Thymol was orally administrated for two days before cisplatin injection and continued for 4 days. (99m)Tc-DMSA was injected through the tail of mice after the drug administration. The percentage of the injected dose per gram of kidney tissue (%ID/g) was calculated. In other experiment, kidneys of treated mice were assessed for histopathology.

RESULTS

99mTc-DMSA uptake per gram tissue of the kidneys as %ID/g was 85.27±21.81, 45.55±5.50, 65.02±32.21 and 88.46±20.46 in the control, cisplatin, thymol (50 mg/kg)+cisplatin and thymol (150 mg/kg)+cisplatin. Thymol administration with cisplatin resulted in a significant increase in the level of %ID/g. Histopathological examinations showed a protective effect of thymol against cisplatin nephrotoxicity in mice.

CONCLUSION

The results showed that thymol significantly attenuates the cisplatin-induced nephrotoxicity in mice, and 99mTc-DMSA uptake in kidney is a suitable method for assessment of nephrotoxicity in mice.

Ameliorative effects of thyme and calendula extracts alone or in combination against aflatoxins-induced oxidative stress and genotoxicity in rat liver

The aims of the current work were to evaluate the hepatoprotective effect of calendula flowers and/or thyme leave extracts on aflatoxins (AFs)-induced oxidative stress, genotoxicity and alteration of p53 bax and bcl2 gene expressions. Eighty male Sprague-Dawley rats were divided into eight equal groups including: the control group, the group fed AFs-contaminated diet (2.5 mg/kg diet) for 5 weeks, the groups treated orally with thyme and/or calendula extract (0.5 g/kg b.w) for 6 weeks and the groups pretreated orally with thyme and/or calendula extract 1 week before and during AFs treatment for further 5 weeks. Blood, liver and bone marrow samples were collected for biochemical analysis, gene expression, DNA fragmentation and micronucleus assay. The results showed that AFs induced significant alterations in oxidative stress markers, increased serum AFP and inflammatory cytokine, percentage of DNA fragmentation, the expression of pro-apoptotic gene p53 and bax accompanied with a decrease in the expression of bcl2. Animals treated with the extracts 1 week before AFs treatment showed a significant decrease in oxidative damage markers, micronucleated cells, DNA fragmentation and modulation of the expression of pro-apoptotic genes. These results suggested that both calendula and thyme extracts had anti-genotoxic effects due to their higher content of total phenolic compounds.

In vivo radioprotective potential of thymol, a monoterpene phenol derivative of cymene

The radioprotective and anticlastogenic potential of a phenol derivative monoterpene thymol(TOH), against whole-body gamma radiation was studied in Swiss albino mice. Acute toxicity of TOH, with an LD(50(14)) of 1134.03mg/kgbwt., was observed when administered intra-peritoneally (i.p.). The radioprotective potential of TOH was evaluated using the optimal dose of 10mg/kgbwt. TOH, which increased the LD(50/30) by 2.17Gy and resulted in a dose reduction factor (DRF) of 1.25. A significant (p<0.01) reduction in micronucleated, polychromatic erythrocytes (PCE), normochromatic erythrocytes (NCE), and an increased PCE/NCE ratio was also observed after administration of 10mg/kg.b.wt. TOH prior to gamma radiation, indicating its antigenotoxic effect. TOH pre-treatment significantly (p<0.01) elevated reduced glutathione, glutathione-S-transferase, catalase, and superoxide dismutase levels and decreased lipid peroxidation levels in mouse liver homogenates at 24 and 48h after exposure to 4.5Gy of radiation. Further, TOH treatment before exposure to 7.5Gy of gamma radiation resulted in a significant (p<0.01) increase in hematological parameters at various post-treatment time points, with increased numbers of endogenous spleen colonies as well. The histological observations indicated a decline in villus heights and crypt numbers in mouse jejunum and were accompanied by a significant decrease in bone marrow nucleated cells in the irradiated group, which was almost normalized by pre-treatment with TOH. Our study clearly documents the antioxidant, anticlastogenic and radioprotective potentials of TOH, which may be attributed to several possible mechanisms, such as normalization of intracellular antioxidant levels and free radical scavenging activities by TOH.

Antioxidant properties of Thymus vulgaris oil against aflatoxin-induce oxidative stress in male rats

The leafy parts of thyme and its essential oil have been used in foods for the flavor, aroma and preservation and also in folk medicines. The aim of the current study was to determine the components of Thymus vulgaris L essential oil and to evaluate the protective effects of this oil against aflatoxin-induce oxidative stress in rats. Thirty six mature male Sprague-Dawley were divided into six treatment groups and treated for 2 weeks as follows: control group; the groups treated orally with low and high doses of T. vulgaris oil (5 and 7.5 mg/kg b.w.); the group fed AFs-contaminated diet (2.5 mg/kg diet) and the groups fed AFs-contaminated diet and treated orally with the oil at the two tested doses. Blood and tissue samples were collected at the end of treatment period for biochemical study and histological examination. The results indicated that the oil contains Carvarcrol (45 mg/g), Thymol (24.7 mg/g), β-Phellandrene (9.7 mg/g), Linalool (4.1 mg/g), Humuline (3.1 mg/g), α-Phellandrene (2.3 mg/g) and Myrcene (2.1 mg/g). However, α and β-pinene, Myrcene, α-thyjone, Tricyclene, 1, 8-cineole, and β-sabinene were found in lower concentrations. Treatment with AFs alone disturbs lipid profile in serum, decreases Total antioxidant capacity, increase creatinine, uric acid and nitric oxide in serum and lipid peroxidation in liver and kidney accompanied with a sever histological changes in the liver tissues. The oil alone at the two tested doses did not induce any significant changes in the biochemical parameters or the histological picture. The combined treatment showed significant improvements in all tested parameters and histological pictures in the liver tissues. Moreover, this improvement was more pronounced in the group received the high dose of the oil. It could be concluded that the essential oil of T. vulgaris has a potential antioxidant activity and a protective effect against AFs toxicity and this protection was dose dependent.

Modulation of gamma ray-induced genotoxic effect by thymol, a monoterpene phenol derivative of cymene

The radioprotective effect of thymol (TOH), a monoterpene phenol, on radiation-induced DNA damage was analyzed in vitro. Chinese hamster lung fibroblast cells (V79) were treated with different concentrations of TOH (0-100 µg/mL) for 1 hour before exposure to 3 Gy gamma irradiation, and then cytokinesis-blocked micronucleus and single-cell gel electrophoresis (comet assay) assays were used to evaluate the radiation-induced cytogenetic damage and genotoxic effects. Furthermore, the modulating effect of TOH on radiation-induced cell death was assessed by apoptotic and necrotic cell detection by staining with ethidium bromide/acridine orange using fluorescence microscopy. To understand the mechanism of TOH-imparted cytoprotection, mitochondrial membrane potential (MMP) was detected by flow cytometry after staining the cells with Rhodamine 123. Pretreatment of V79 cells with various concentrations of TOH (0-100 µg/mL) for 1 hour reduced the radiation-induced micronuclei as well as percent tail DNA and mean Olive tail moment with a maximum protective effect observed at TOH (25 µg/mL). Apoptosis by microscopic, MMP measurements indicated that the V79 cells exposed to gamma radiation alone showed a maximal increase in the number of early and late apoptotic and necrotic cell death associated with a significant loss of the MMP. Pretreatment with TOH (25 µg/mL) showed a significant (P < .01) decrease in the level of apoptotic fraction as well as necrotic cells and suppressed the radiation-induced collapse of MMP when compared with the radiation alone group. These results suggest that TOH suppresses radiation-induced genotoxicity, apoptosis, and necrosis primarily by the free radical scavenging and modulation of oxidative stress.

Subinhibitory concentrations of thymol reduce enterotoxins A and B and alpha-hemolysin production in Staphylococcus aureus isolates

Background

Targeting bacterial virulence factors is now gaining interest as an alternative strategy to develop new types of anti-infective agents. It has been shown that thymol, when used at low concentrations, can inhibit the TSST-1 secretion in Staphylococcus aureus. However, there are no data on the effect of thymol on the production of other exotoxins (e.g., α-hemolysin and enterotoxins) by S. aureus.

Methodology/Principal Findings

Secretion of α-hemolysin, SEA and SEB in both methicillin-sensitive and methicillin-resistant S. aureus isolates cultured with graded subinhibitory concentrations of thymol was detected by immunoblot analysis. Hemolysin and tumor necrosis factor (TNF) release assays were performed to elucidate the biological relevance of changes in α-hemolysin, SEA and SEB secretion induced by thymol. In addition, the influence of thymol on the transcription of hla, sea, and seb (the genes encoding α-hemolysin, SEA and SEB, respectively) was analyzed by quantitative RT-PCR. Thymol inhibited transcription of hla, sea and seb in S. aureus, resulting in a reduction of α-hemolysin, SEA and SEB secretion and, thus, a reduction in hemolytic and TNF-inducing activities.

Conclusions/Significance

Subinhibitory concentrations of thymol decreased the production of α-hemolysin, SEA and SEB in both MSSA and MRSA in a dose-dependent manner. These data suggest that thymol may be useful for the treatment of S. aureus infections when used in combination with β-lactams and glycopeptide antibiotics, which induce expression of α-hemolysin and enterotoxins at subinhibitory concentrations. Furthermore, the structure of thymol may potentially be used as a basic structure for development of drugs aimed against these bacterial virulence factors.

Thymol and its Derivatives as Antimicrobial Agents

From the seeds of C arum copticum thymol (1) was isolated as the major component and ten derivatives (2–11) were prepared by reacting it with different acid chlorides in a single step. They were evaluated for antimicrobial activity against twelve bacterial strains and nine fungal strains using disc diffusion and broth dilution assays. Derivative 9 was found to be most active against both bacterial and fungal strains.

Effects of oregano, carvacrol and thymol on Staphylococcus aureus and Staphylococcus epidermidis biofilms

The aim of this study was to evaluate the effect of oregano essential oil, carvacrol and thymol on biofilm-grown Staphylococcus aureus and Staphylococcus epidermidis strains, as well as the effects of the oils on biofilm formation. For most of the S. aureus (n=6) and S. epidermidis (n=6) strains tested, the biofilm inhibitory concentration (0.125–0.500 %, v/v, for oregano, and 0.031–0.125 %, v/v, for carvacrol and thymol) and biofilm eradication concentration (0.25–1.0 %, v/v, for oregano and 0.125–0.500 %, v/v, for carvacrol and thymol) values were twofold or fourfold greater than the concentration required to inhibit planktonic growth. Subinhibitory concentrations of the oils attenuated biofilm formation of S. aureus and S. epidermidis strains on polystyrene microtitre plates.

Surface activity of thymol: implications for an eventual pharmacological activity

In the present work, we studied the ability of thymol to affect the organization of model membranes and the activity of an intrinsic membrane protein, the GABA(A) receptor (GABA(A)-R). In this last aspect, we tried to elucidate if the action mechanism of this terpene at the molecular level, involves its binding to the receptor protein, changes in the organization of the receptor molecular environment, or both. The self-aggregation of thymol in water with a critical micellar concentration approximately = 4 microM and its ability to penetrate in monomolecular layers of soybean phosphatidylcholine (sPC) at the air-water interface, even at surface pressures above the equilibrium, lateral pressure of natural bilayers were demonstrated. Thymol affected the self-aggregation of Triton X-100 and the topology of sPC vesicles. It also increased the polarity of the membrane environment sensed by the electrochromic dye merocyanine. A dipolar moment of 1.341 Debye was calculated from its energy-minimized structure. Its effect on the binding of [3H]-flunitrazepam ([3H]-FNZ) to chick brain synaptosomal membranes changed qualitatively from a tendency to the inhibition to a clear activatory regime, up on changing the phase state of the terpene (from a monomeric to a self-aggregated state). Above its CMC, thymol increased the affinity of the binding of [3H]-FNZ (K(d-control)= 2.9, K(d-thymol)= 1.7 nM) without changing the receptor density (B(max-control)= 910, B(max-thymol)= 895 fmol/mg protein). The activatory effect of thymol on the binding of [ [3H]-FNZ was observed even in the presence of the allosteric activator gamma-aminobutyric acid (GABA) at a concentration of maximal activity, and was blocked by the GABA antagonist bicuculline. Changes in the dipolar arrangement and in the molecular packing of GABA(A)-R environment are discussed as possible mediators of the action mechanism of thymol.