Thymol, a naturally occurring monocyclic dietary phenolic compound protects Chinese hamster lung fibroblasts from radiation-induced cytotoxicity

Effects of Lamiaceae family plants and their bioactive ingredients on coronavirus-induced lung inflammation

Coronaviruses (CoVs) are a family of viruses that cause infection in respiratory and intestinal systems. Different types of CoVs, those responsible for the SARS-CoV and the new global pandemic of coronavirus disease 2019 in people, have been found. Some plants were used as food additives: spices and dietary and/or medicinal purposes in folk medicine. We aimed to provide evidence about possible effects of two Lamiaceae family plants on control or treatment of CoVs-induced inflammation. The keywords including coronaviruses, Thymus vulgaris, Zataria multiflora, thymol, carvacrol, antivirus, and anti-inflammatory and antioxidant effects were searched in various databases such as PubMed, Web of Sciences (ISI), and Google Scholar until September 2022. The medicinal herbs and their main ingredients, thymol and carvacrol, showed antiviral properties and reduced inflammatory mediators, including IL-1β; IL-6, and TNF-α, at both gene and protein levels but increased the levels of IFN-γ in the serum as anti-inflammatory cytokine. These medicinal herbs and their constituents also reduce oxidative stress and enhance antioxidant capacity. The results of molecular docking analyses also indicated that polyphenol components such as thymol, carvone, and carvacrol could inhibit the entry of the viruses into the host cells in molecular docking analyses. The antiviral, anti-inflammatory, and antioxidant effects of these plants may be due to actions of their phenolic compounds that modulate immune response and may be useful in the control and treatment of CoV-induced lung disorder.

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Protective Effects of Natural Antioxidants on Inflammatory Bowel Disease: Thymol and Its Pharmacological Properties

Inflammatory bowel disease (IBD) is a gastrointestinal disease that involves chronic mucosal or submucosal lesions that affect tissue integrity. Although IBD is not life-threatening, it sometimes causes severe complications, such as colon cancer. The exact etiology of IBD remains unclear, but several risk factors, such as pathogen infection, stress, diet, age, and genetics, have been involved in the occurrence and aggravation of IBD. Immune system malfunction with the over-production of inflammatory cytokines and associated oxidative stress are the hallmarks of IBD. Dietary intervention and medical treatment suppressing abnormal inflammation and oxidative stress are recommended as potential therapies. Thymol, a natural monoterpene phenol that is mostly found in thyme, exhibits multiple biological functions as a potential adjuvant for IBD. The purpose of this review is to summarize current findings on the protective effect of thymol on intestinal health in the context of specific animal models of IBD, describe the role of thymol in the modulation of inflammation, oxidative stress, and gut microbiota against gastrointestinal disease, and discuss the potential mechanism for its pharmacological activity.

Radioprotective Potential of Nutraceuticals and their Underlying Mechanism of Action

Radiations are an efficient treatment modality in cancer therapy. Besides the treatment effects of radiations, the ionizing radiations interact with biological systems and generate reactive oxygen species that interfere with the normal cellular process. Previous investigations of synthetic radioprotectors have shown less effectiveness, mainly owing to some limiting effects. The nutraceuticals act as efficient radioprotectors to protect the tissues from the deleterious effects of radiation. The main radioprotection mechanism of nutraceuticals is the scavenging of free radicals while other strategies are involved modulation of signaling transduction of pathways like MAPK (JNK, ERK1/2, ERK5, and P38), NF-kB, cytokines, and their protein regulatory genes expression. The current review is focused on the radioprotective effects of nutraceuticals including vitamin E, -C, organosulphur compounds, phenylpropanoids, and polysaccharides. These natural entities protect against radiation-induced DNA damage. The review mainly entails the antioxidant perspective and mechanism of action of their radioprotective activities on a molecular level, DNA repair pathway, anti-inflammation, immunomodulatory effects, the effect on cellular signaling pathways, and regeneration of hematopoietic cells.

Radioprotective Effects of Plants from the Lamiaceae Family

BACKGROUND

Edible and medicinal plants are still an interesting source of promising biologically active substances to drug discovery and development. At a time of increasing cancer incidence in the world, alleviating the bothersome side effects of radiotherapy in debilitated cancer patients is becoming an important challenge.

OBJECTIVE

The aim of the study was to overview the literature data concerning the radioprotective activity of extracts, essential oils, and some chemical compounds obtained from 12 species belonging to the Lamiaceae family, gathering of numerous spice and medicinal plants rich in valuable phytochemicals.

RESULTS AND CONCLUSION

The analysis of available publications showed radioprotective effectiveness of essential oils and complex extracts containing phenolic acids and flavonoids in various in vitro and in vivo models. Relatively welldocumented preventive properties exhibited the following species: Mentha × piperita, Ocimum tenuiflorum, Origanum vulgare, and Rosmarinus officinalis. However, few plants such as Lavandula angustifolia, Mentha arvensis, M. spicata, Plectranthus amboinicus, Salvia miltiorrhiza, S. officinalis, Scutellaria baicalensis, and Zataria multiflora should be more investigated in the future. Among the mechanisms of radioprotective effects of well-studied extracts and phytochemicals, it can be mentioned mainly the protection against chromosomal damage, scavenging free radicals, decreasing of lipid peroxidation and elevating of glutathione, superoxide dismutase, catalase, and alkaline phosphatase enzyme levels as well as the reduction the cell death. The plant substances protected the gastrointestinal tract, bone marrow and lung fibroblasts. In conclusion, studied species of Lamiaceae family and their active chemical compounds are potent in alleviating the side effects of radiotherapy and should be considered as a complementary therapy.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Naringin abates adverse effects of cadmium-mediated hepatotoxicity: An experimental study using HepG2 cells

This study investigated the protective potential of Naringin (NIN) against cadmium chloride (CdCl₂ ) mediated hepatotoxicity using human hepatocellular carcinoma (HepG2) cells. An optimal concentration of NIN (5 μM) was potent enough to confer cytoprotection against CdCl₂ (50 μM) as was observed by MTT assay. Preconditioning with NIN maintained redox homeostasis, mitochondrial membrane potential, and reduced apoptosis as marked by decrease in the percentage sub-G₀ /G₁ and Annexin V-FITC/propidium iodide positive cells (apoptotic). NIN pretreatment maintained the levels of protein thiol along with endogenous activities of Superoxide dismutase, Glutathione S-transferase, and Catalase and lowered lipid peroxidation. Decreased Bax/Bcl2 ratio along with reduced Caspase 3 cleavage and Cytochrome c release indicated that NIN conditioning blocked mitochondrial-mediated apoptosis. Increased Nrf2 and metallothionein (MT) acted as adaptive response in the presence of cadmium. Thus, the protective mechanism of NIN is attributed to its antioxidant potential which aids in redox homeostasis and prevents CdCl₂ mediated cytotoxicity.

Evaluation of antibacterial potential and toxicity of plant volatile compounds using new broth microdilution volatilization method and modified MTT assay

With aim to develop effective proof-of-concept approach which can be used in a development of new preparations for the inhalation therapy, we designed a new screening method for simple and rapid simultaneous determination of antibacterial potential of plant volatiles in the liquid and the vapour phase at different concentrations. In addition, EVA (ethylene vinyl acetate) capmat™ as vapour barrier cover was used as reliable modification of thiazolyl blue tetrazolium bromide (MTT) assay for cytotoxicity testing of volatiles on microtiter plates. Antibacterial activity of carvacrol, cinnamaldehyde, eugenol, 8-hydroxyquinoline, thymol and thymoquinone was determined against Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pneumoniae using new broth microdilution volatilization method. The cytotoxicity of these compounds was evaluated using MTT test in lung fibroblast cells MRC-5. The most effective antibacterial agents were 8-hydroxyquinoline and thymoquinone with the lowest minimum inhibitory concentrations (MICs) ranging from 2 to 128μg/mL, but they also possessed the highest toxicity in lung cell lines with half maximal inhibitory concentration (IC₅₀) values 0.86-2.95μg/mL. The lowest cytotoxicity effect was identified for eugenol with IC₅₀ 295.71μg/mL, however this compound produced only weak antibacterial potency with MICs 512-1024μg/mL. The results demonstrate validity of our novel broth microdilution volatilization method, which allows cost and labour effective high-throughput antimicrobial screening of volatile agents without need of special apparatus. In our opinion, this assay can also potentially be used for development of various medicinal, agricultural, and food applications that are based on volatile antimicrobials.

In vitro Protective Effect of Rutin and Quercetin against Radiation-induced Genetic Damage in Human Lymphocytes

Purpose of the Study:

Rutin (RUT) and quercetin (QRT) which are dietary compounds were investigated for their ability to protect against ionizing radiation (IR)-induced genotoxicity in human lymphocytes.

Materials and Methods:

The radiation antagonistic potential of RUT and QRT was assessed by alkaline comet and cytokinesis-block micronucleus (CBMN) assay.

Results:

Treatment of lymphocytes with RUT and QRT (25 μg/ml) prior exposure to 2 Gy gamma radiation resulted in a significant reduction of frequency of micronuclei as compared to the control set of cells evaluated by CBMN assay. Similarly, treatment of lymphocytes with RUT and QRT before radiation exposure showed significant decrease in the DNA damage as assessed by comet parameters, such as percent tail DNA and olive tail moment.

Conclusion:

The study demonstrates the protective effect of RUT and QRT against IR-induced DNA damage in human lymphocytes, which may be partly attributed to scavenging of IR-induced free radicals and also by the inhibition of IR-induced oxidative stress.

Hydroxytyrosol, a dietary phenolic compound forestalls the toxic effects of methylmercury-induced toxicity in IMR-32 human neuroblastoma cells

This study demonstrates the protective potential of hydroxytyrosol (HT), an olive oil phenol, against methylmercury (MeHg)-induced neurotoxicity using IMR-32 human neuroblastoma cell line. HT inhibited MeHg-induced cytotoxicity and genotoxicity as confirmed by MTT, micronucleus, and comet assays. Cells preconditioned with HT showed reduction of MeHg-induced cellular oxidative stress along with the maintenance of glutathione, superoxide dismutase, glutathione-S-tranferase, and catalase. Fluorescence microscopy and DNA ladder assays indicated the inhibitory effect of HT against MeHg-induced apoptosis, which was further established by Western blotting. An effective concentration of 5 µM HT caused downregulation of p53, bax, cytochrome c, and caspase 3 and upregulation of prosurvival proteins including nuclear factor erythroid 2-related factor 2 (Nrf2) and metallothionein. This work indicates the cytoprotective potential of HT against MeHg-induced toxicity primarily by the lowering of oxidative stress, which may be endorsed to its antigenotoxic and antiapoptotic potential, in addition to its free radical scavenging ability. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1264-1275, 2016.

A carvacrol-thymol blend decreased intestinal oxidative stress and influenced selected microbes without changing the messenger RNA levels of tight junction proteins in jejunal mucosa of weaning piglets

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.

Kazakh Ziziphora Species as Sources of Bioactive Substances

Ziziphora species represent the prototypical example of the Lamiaceae family. The phytochemicals present in Ziziphora include monoterpenic essential oils, triterpenes and phenolic substances belonging to the flavonoids. In Kazakh traditional medicine, Ziziphora species possess several medicinal uses. In particular, Z. bungeana Lam. and Z. clinopodioides Lam. are used for the treatment of illnesses related to the cardiovascular system or to combat different infections. Unfortunately, the majority of the information about the complex Ziziphora species is only available in Russian and Chinese language, therefore, we decided gather all available information on Kazakhstan Ziziphora, namely its content compounds, medicinal uses and published patents, to draw the attention of scientists to this very interesting plant with high medicinal potential.

Effects of UV Rays and Thymol/Thymus vulgaris L. Extract in an ex vivo Human Skin Model: Morphological and Genotoxicological Assessment

Ultraviolet (UV) radiation is the major environmental factor affecting functions of the skin. Compounds rich in polyphenols, such as Thymus vulgaris leaf extract and thymol, have been proposed for the prevention of UV-induced skin damage. We compared the acute effects induced by UVA and UVB rays on epidermal morphology and proliferation, cytotoxicity, and genotoxicity. Normal human skin explants were obtained from young healthy women (n = 7) after informed consent and cultured at the air-liquid interface overnight. After 24 h, the samples were divided in 2 groups: the former exposed to UVA (16 or 24 J/cm2) and the latter irradiated with UVB (0.24 or 0.72 J/cm2). One hour after the end of irradiation, supernatants were collected for evaluation of the lactate dehydrogenase activity. Twenty-four hours after UVB exposure, biopsies were processed for light and transmission electron microscopy analysis, proliferation, cytotoxicity, and genotoxicity. UVB and UVA rays induced early inhibition of cell proliferation and DNA damage compared to controls. In particular, UVB rays were always more cytotoxic and genotoxic than UVA ones. For this reason, we evaluated the effect of either T. vulgaris L. extract (1.82 µg/ml) or thymol (1 µg/ml) on all samples treated for 1 h before UVB irradiation. While Thymus had a protective action for all of the endpoints evaluated, the action of the extract was less pronounced on epidermal proliferation and morphological features. The results presented in this study could be the basis for investigating the mechanism of thymol and T. vulgaris L. extract against the damage induced by UV radiation.

Radioprotective Agents: Strategies and Translational Advances

Radioprotectors are agents required to protect biological system exposed to radiation, either naturally or through radiation leakage, and they protect normal cells from radiation injury in cancer patients undergoing radiotherapy. It is imperative to study radioprotectors and their mechanism of action comprehensively, looking at their potential therapeutic applications. This review intimately chronicles the rich intellectual, pharmacological story of natural and synthetic radioprotectors. A continuous effort is going on by researchers to develop clinically promising radioprotective agents. In this article, for the first time we have discussed the impact of radioprotectors on different signaling pathways in cells, which will create a basis for scientific community working in this area to develop novel molecules with better therapeutic efficacy. The bright future of exceptionally noncytotoxic derivatives of bisbenzimidazoles is also described as radiomodulators. Amifostine, an effective radioprotectant, has been approved by the FDA for limited clinical use. However, due to its adverse side effects, it is not routinely used clinically. Recently, CBLB502 and several analog of a peptide are under clinical trial and showed high success against radiotherapy in cancer. This article reviews the different types of radioprotective agents with emphasis on the strategies for the development of novel radioprotectors for drug development. In addition, direction for future strategies relevant to the development of radioprotectors is also addressed.

Antifungal activity and mode of action of thymol and its synergism with nystatin against Candida species involved with infections in the oral cavity: an in vitro study

BACKGROUND

Limitations of antifungal agents used in the treatment of oral candidiasis, as the development of resistant strains, are known by the scientific community. In this context, the aim of this study was to evaluate the antifungal activity of thymol against Candida albicans, Candida tropicalis and Candida krusei strains and to determine its mode of action and synergistic effect when combined with the synthetic antifungal nystatin.

METHODS

The minimum inhibitory concentration (MIC) was determined using a microdilution technique, and the minimum fungicidal concentration (MFC) was determined via subculture sowing. The mode of action of thymol was established by verifying fungal growth in the presence of sorbitol or ergosterol. The fractional inhibitory concentration index (FIC) was determined using the checkerboard method.

RESULTS

Thymol presented an antifungal effect, with MICs of 39 μg/mL for C. albicans and C. krusei and 78 μg/mL for C. tropicalis. The results of the antifungal test remained unchanged in the presence of sorbitol; however, the MIC value of thymol against C. albicans increased eight times (from 39.0 to 312.5 μg/mL) in presence of exogenous ergosterol. The combination of thymol and nystatin reduced the MIC values of both products by 87.4%, generating an FIC index of 0.25.

CONCLUSIONS

Thymol was found to have a fungicidal effect on Candida species and a synergistic effect when combined with nystatin.

Thymol, a monoterpene phenolic derivative of cymene, abrogates mercury-induced oxidative stress resultant cytotoxicity and genotoxicity in hepatocarcinoma cells

Thymol (TOH) was investigated for its ability to protect against mercuric chloride (HgCl2 )-induced cytotoxicity and genotoxicity using human hepatocarcinoma (HepG2) cell line. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay confirmed the efficacy of TOH pretreatment in attenuating HgCl2 -induced cytotoxicity. Pretreatment with TOH inhibited HgCl2 -induced genotoxicity, depolarization of mitochondrial membrane, oxidative stress, and mitochondrial superoxide levels. Interestingly, TOH (100 µM) alone elevated the intracellular basal glutathione S-transferase (GST) levels and TOH pretreatment abrogated the decrease in glutathione, GST, superoxide dismutase, and catalase levels even after HgCl2 intoxication. Furthermore, TOH was also capable of inhibiting HgCl2 -induced apoptotic as well as necrotic cell death analyzed by flowcytometric analysis of cells dual stained with Annexin-FITC/propidium iodide. The present findings clearly indicate the cytoprotective potential of TOH against HgCl2 -induced toxicity, which may be attributed to its free radical scavenging ability which facilitated in reducing oxidative stress and mitochondrial damage thereby inhibiting cell death.

Chrysanthemum boreale flower floral water inhibits platelet-derived growth factor-stimulated migration and proliferation in vascular smooth muscle cells

CONTEXT

Chrysanthemum boreale Makino (Compositae) (CBM) is a traditional medicine that has been used for the prevention or treatment of various disorders; it has various properties including antioxidation, anti-inflammation, and antitumor.

OBJECTIVE

The present study was designed to explore the in vitro effect of CBM flower floral water (CBMFF) on atherosclerosis-related responses in rat aortic smooth muscle cells (RASMCs).

MATERIALS AND METHODS

CBMFF was extracted from CBM flower by steam distillation and analyzed using gas chromatography-mass spectrometry. The anti-atherosclerosis activity of CBMFF was tested by estimating platelet-derived growth factor (PDGF)-BB (10 ng/mL)-induced proliferation and migration levels and intracellular kinase pathways in RASMCs at CBMFF concentrations of 0.01-100 μM and analyzing ex vivo aortic ring assay.

RESULTS

Gas chromatography-mass spectrometry showed that the CBMFF contained a total of seven components. The CBMFF inhibits PDGF-BB-stimulated RASMC migration and proliferation (IC50: 0.010 μg/mL). Treatment of RASMCs with PDGF-BB induced PDGFR-β phosphorylation and increased the phosphorylations of MAPK p38 and ERK1/2. CBMFF addition prevented PDGF-BB-induced phosphorylation of these kinases (IC50: 008 and 0.018 μg/mL, for p38 MAPK and ERK1/2, respectively), as well as PDGFR-β (IC50: 0.046 μg/mL). Treatment with inhibitors of PDGFR, P38 MAPK, and ERK1/2 decreased PDGF-BB-increased migration and proliferation in RASMCs. Moreover, the CBMFF suppressed PDGF-BB-increased sprout outgrowth of aortic rings (IC50: 0.047 μg/mL).

DISCUSSION AND CONCLUSION

These results demonstrate that CBMFF may inhibit PDGF-BB-induced vascular migration and proliferation, most likely through inhibition of the PDGFR-β-mediated MAPK pathway; therefore, the CBMFF may be promising candidate for the development of herbal remedies for vascular disorders.

Genoprotective effects of Origanum vulgare ethanolic extract against cyclophosphamide-induced genotoxicity in mouse bone marrow cells

CONTEXT

Cyclophosphamide (CP), an alkylating chemotherapeutic agent, can bind DNA, causing chromosome breaks, micronucleus (Mn) formation, and cell death. Because Origanum vulgare L. (Lamiaceae) has antioxidative properties, it might protect against DNA damage.

OBJECTIVE

The genoprotective effect of O. vulgare ethanolic extract against CP-induced genotoxicity in mouse bone marrow cells was evaluated using a Mn assay.

MATERIALS AND METHODS

Mice were pre-treated with aerial parts of O. vulgare ethanolic extract at different doses (50, 100, 200, or 400 mg/kg) for 7 d. One hour after the last administration of O. vulgare, animals were injected with CP at 200 mg/kg. After 24 h, the bone marrow cells of both femurs were flushed and the frequency of MnPCEs was evaluated to measure the chromosomal damages. In addition, the number of PCEs per 1000 NCEs in each animal was recorded to evaluate the bone-marrow suppression; mitotic activity was calculated as [PCE/(PCE + NCE)] × 100 to assess the cell division.

RESULTS

At 400 mg/kg, O. vulgare displayed its maximum protective effect, reduced the number of MnPCEs from 10.52 ± 1.07 for CP group to 2.17 ± 0.26 and completely normalized the mitotic activity (p < 0.001). Origanum vulgare also led to significant proliferation and hypercellularity of immature myeloid elements after the mice were treated with CP, mitigating the bone marrow suppression.

DISCUSSION AND CONCLUSION

Origanum vulgare ethanolic extract exerts a potent genoprotective effect against CP-induced genotoxicity in mice bone marrow, which might be possibly due to the scavenging of free radicals during oxidative stress conditions.

Assessment of antioxidative, chelating, and DNA-protective effects of selected essential oil components (eugenol, carvacrol, thymol, borneol, eucalyptol) of plants and intact Rosmarinus officinalis oil

Selected components of plant essential oils and intact Rosmarinus officinalis oil (RO) were investigated for their antioxidant, iron-chelating, and DNA-protective effects. Antioxidant activities were assessed using four different techniques. DNA-protective effects on human hepatoma HepG2 cells and plasmid DNA were evaluated with the help of the comet assay and the DNA topology test, respectively. It was observed that whereas eugenol, carvacrol, and thymol showed high antioxidative effectiveness in all assays used, RO manifested only antiradical effect and borneol and eucalyptol did not express antioxidant activity at all. DNA-protective ability against hydrogen peroxide (H2O2)-induced DNA lesions was manifested by two antioxidants (carvacrol and thymol) and two compounds that do not show antioxidant effects (RO and borneol). Borneol was able to preserve not only DNA of HepG2 cells but also plasmid DNA against Fe(2+)-induced damage. This paper evaluates the results in the light of experiences of other scientists.

IgE-mediated mast cell responses are inhibited by thymol-mediated, activation-induced cell death in skin inflammation

BACKGROUND

Mast cells play a critical role in inflammatory skin diseases through releasing proinflammatory mediators; however, few therapies directly target these cells. In 1878, the use of topical thymol, a now recognized potent agonist for transient receptor potential channels, was first described to treat eczema and psoriasis.

OBJECTIVE

We sought to determine the mechanisms through which thymol can alter skin inflammation.

METHODS

We examined the effect of topical thymol on IgE-dependent responses using a mast cell-dependent passive cutaneous anaphylaxis (PCA) model, as well as in vitro-cultured mast cells.

RESULTS

Thymol dose-dependently inhibited PCA when administered topically 24 hours before antigen challenge but provoked an ear-swelling response directly on application. This direct effect was associated with local mast cell degranulation and was absent in histamine-deficient mice. However, unlike with PCA responses, there was no late-phase swelling. In vitro thymol directly triggered calcium flux in mast cells through transient receptor potential channel activation, along with degranulation and cytokine transcription. However, no cytokine protein was produced. Instead, thymol induced a significant increase in apoptotic cell death that was seen both in vitro and in vivo.

CONCLUSIONS

We propose that the efficacy of thymol in reducing IgE-dependent responses is through promotion of activation-induced apoptotic cell death of mast cells and that this likely explains the clinical benefits observed in early clinical reports.

Thymol from Thymus quinquecostatus Celak. protects against tert-butyl hydroperoxide-induced oxidative stress in Chang cells

The present work describes the protective effects of thymol isolated from Thymus quinquecostatus Celak. against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage through various experiments with Chang liver cells. Thymol significantly protected hepatocytes against t-BHP-induced cell cytotoxicity as demonstrated by increased viability. Furthermore, observation of Hoechst staining, annexin V/PI staining, and expression of Bcl-2 and Bax indicated that thymol inhibited t-BHP-induced Chang cell damage. Further, thymol inhibited the loss of mitochondrial membrane potential in t-BHP-treated Chang cells and prevented oxidative stress-triggered reactive oxygen species (ROS) and lipid peroxidation (malondialdehyde, MDA). Thymol restored the antioxidant capability of hepatocytes including glutathione (GSH) levels which were reduced by t-BHP. These results indicated that thymol prevents oxidative stress-induced damage to liver cells through suppression of ROS and MDA levels and increase of GSH level.

Sesamol prevents doxorubicin-induced oxidative damage and toxicity on H9c2 cardiomyoblasts

Objectives

Exposure to toxicants like doxorubicin (Dox) damages cellular components by generating reactive oxygen species (ROS). This can be attenuated using free radical scavengers and/or antioxidants.

Methods

Dox-exposed cardiac myoblasts (H9c2 cells) were treated with sesamol (12.5, 25 and 50 μm), a natural phenolic compound. Intracellular ROS inhibition, cell viability and analysis of antioxidant and biochemical markers such as superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, reduced/oxidized glutathione, lipid peroxidation and protein carbonyl content were performed. The effect of sesamol treatment on the cytotoxic and genotoxic parameters was studied by monitoring the signalling proteins involved in the apoptotic pathway.

Key findings

Dox triggered cellular and genetic damage by increasing levels of intracellular ROS, thereby decreasing cell viability and increasing apoptosis. Sesamol reversed the cytotoxic and genotoxic effects of Dox. In addition, sesamol attenuated the pro-apoptotic proteins and improved the anti-apoptotic status. Sesamol pre-treatment also alleviated the disturbed antioxidant milieu by preventing ROS production and improving endogenous enzyme levels.

Conclusions

Among the different doses tested, 50 μm of sesamol showed maximum protection against Dox-induced oxidative damage. This reflects the significance of sesamol in ameliorating the deleterious effects associated with cancer chemotherapy.

Polyphenolic fraction of Pilea microphylla (L.) protects Chinese hamster lung fibroblasts against γ-radiation-induced cytotoxicity and genotoxicity

Present study was designed to compare cytoprotective and antigenotoxic activity of the polyphenolic fraction of Pilea microphylla (PM1) with that of its active polyphenolic constituents against γ-radiation in V79 cells. PM1 was standardized with respect to the polyphenols present by RP-HPLC. It was evaluated for its free radical scavenging potential using Fenton reaction-induced DNA damage and lipid peroxidation. Further, PM1 was subjected against γ-radiation-induced cytotoxicity and genotoxicity in V79 cells. PM1 significantly reduced free radical-mediated calf thymus DNA damage and lipid peroxidation. Among the concentrations tested (12.5, 25 and 50 μg/ml) for radioprotection, PM1 at 25 μg/ml exhibited maximum protection. Further, when compared with constituent polyphenols viz., rutin, quercetin and chlorogenic acid (concentrations equivalent to that present in PM1-25 μg/ml), a combination of polyphenols was found most effective in preventing γ-radiation-induced cytotoxicity and genotoxicity. To conclude, radioprotection is possibly a synergistic effect of the phytochemicals present in the herbal extract, rather than any single component.

Effect of thymol on Ca2+ homeostasis and viability in MG63 human osteosarcoma cells

AIMS

The effect of the natural product thymol on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in MG63 human osteosarcoma cells was examined.

METHODS

The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i).

RESULTS

Thymol at concentrations of 200-1,000 μmol/l induced a [Ca(2+)](i) rise in a concentration-dependent fashion. The response was decreased partially by removal of extracellular Ca(2+). Thymol-induced Ca(2+) entry was inhibited by nifedipine, econazole, SK&F96365 and protein kinase C modulators. When extracellular Ca(2+) was removed, incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited the thymol-induced [Ca(2+)](i) rise. Incubation with thymol also inhibited the thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 abolished the thymol-induced [Ca(2+)](i) rise. At concentrations of 100-600 μmol/l, thymol killed cells in a concentration-dependent manner. This cytotoxic effect was not changed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/AM. Annexin V/propidium iodide staining data suggest that thymol (200 and 400 μmol/l) induced apoptosis in a concentration-dependent manner. Thymol (200 and 400 μmol/l) also increased levels of reactive oxygen species.

CONCLUSIONS

In MG63 cells, thymol induced a [Ca(2+)](i) rise by inducing phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via protein kinase C-sensitive store-operated Ca(2+) channels. Thymol induced cell death that may involve apoptosis via mitochondrial pathways.

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.

Effect of thymol on Ca2+ homeostasis and viability in human glioblastoma cells

The effect of the natural essential oil thymol on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in human glioblastoma cells was examined. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i). Thymol at concentrations of 400-1000 μM induced a [Ca(2+)](i) rise in a concentration-dependent fashion. The response was decreased partially by removal of extracellular Ca(2+). Thymol-induced Ca(2+) signal was not altered by nifedipine, econazole, SK&F96365, and protein kinase C activator phorbol myristate acetate (PMA), but was inhibited by the protein kinase C inhibitor GF109203X. When extracellular Ca(2+) was removed, incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) abolished thymol-induced [Ca(2+)](i) rise. Incubation with thymol also abolished thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 abolished thymol-induced [Ca(2+)](i) rise. At concentrations of 200-800 μM, thymol killed cells in a concentration-dependent manner. This cytotoxic effect was not changed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxy methyl (BAPTA/AM). Annexin V/propidium iodide staining data suggest that thymol (200, 400 and 600 μM) induced apoptosis in a concentration-dependent manner. Collectively, in human glioblastoma cells, thymol induced a [Ca(2+)](i) rise by inducing phospholipase C- and protein kinase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via non store-operated Ca(2+) channels. Thymol induced cell death that may involve apoptosis.

Phenylpropanoids in radioregulation: double edged sword

Radiotherapy, frequently used for treatment of solid tumors, carries two main obstacles including acquired radioresistance in cancer cells during radiotherapy and normal tissue injury. Phenylpropanoids, which are naturally occurring phytochemicals found in plants, have been identified as potential radiotherapeutic agents due to their anti-cancer activity and relatively safe levels of cytotoxicity. Various studies have proposed that these compounds could not only sensitize cancer cells to radiation resulting in inhibition of growth and cell death but also protect normal cells against radiation-induced damage. This review is intended to provide an overview of recent investigations on the usage of phenylpropanoids in combination with radiotherapy in cancer treatment.

The radioprotective effect of Zataria multiflora against genotoxicity induced by γ irradiation in human blood lymphocytes

The radioprotective effect of hydroalcholic Zataria multiflora (Avishan-e shirazi) extract was investigated against genotoxicity induced by γ irradiation in human lymphocytes. Peripheral blood samples were collected from human volunteers and incubated with Z. multiflora extract at different concentrations (5, 10, and 50 μg/mL) for 1 hour. At each dose point, the whole blood was exposed in vitro to 150 cGy of cobalt-60 γ irradiation, and then the lymphocytes were cultured with mitogenic stimulation to determine number of the micronuclei in cytokinesis-blocked binucleated cells. The treatment of lymphocytes with extract showed a significant decrease in the incidence of micronuclei binucleated cells, compared with similarly irradiated lymphocytes without extract against γ irradiation. The maximum protection and decrease in frequency of micronuclei was observed at 50 μg/mL of Zataria extract by 32% reduction. High-performance liquid chromatography analysis of extract showed that it contains high amounts of thymol. Zataria extract exhibited concentration-dependent radical-scavenging activity on 1,1-diphenyl-2-picryl hydrazyl free radicals. These data have an important application for the protection of human lymphocyte from the genetic damage and side-effects induced by γ irradiation in personnel exposed to radiation.

Effect of thymol on peripheral blood mononuclear cell PBMC and acute promyelotic cancer cell line HL-60

Thymol, a naturally occurring phenolic compound, has been known for its antioxidant, anti microbial, and anti inflammatory activity. Thymol has also been reported as anti-cancer agent, but its anti-cancer mechanism has not yet been fully elucidated. Thus, we aimed to investigate anticancer activity of thymol on HL-60 (acute promyelotic leukemia) cells. In our study, thymol demonstrated dose dependent cytotoxic effects on HL-60 cells after 24h of exposure. However, thymol did not show any cytotoxic effect in normal human PBMC. The cytotoxic effect of thymol on HL-60 cells appears to be associated with induction of cell cycle arrest at sub G0/G1 phase, and apoptotic cell death based on genomic DNA fragmentation pattern. Thymol also showed significant increase in production of reactive oxygen species (ROS) activity, increase in mitochondrial H(2)O(2) production and depolarization of mitochondrial membrane potential. On performing Western Blot analysis, thymol showed increase in Bax protein level with a concomitant decrease in Bcl2 protein expression in a dose dependent manner. Our study also showed activation of caspase -9, -8 and -3 and concomitant PARP cleavage, which is the hallmark of caspase-dependent apoptosis. Moreover, to rule out the involvement of other mechanisms in apoptosis induction by thymol, we also studied its effect on apoptosis inducing factor (AIF). Thymol induced AIF translocation from mitochondria to cytosol and to nucleus, thus indicating its ability to induce caspase independent apoptosis. We conclude that, thymol-induced apoptosis in HL-60 cells involves both caspase dependent and caspase independent pathways.

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.