Eugenol inhibit 7,12-dimethylbenz[a]anthracene-induced genotoxicity in MCF-7 cells: Bifunctional effects on CYP1 and NAD(P)H:quinone oxidoreductase

Pharmacodynamic, pharmacokinetic, toxicity, and recent advances in Eugenol's potential benefits against natural and chemical noxious agents: A mechanistic review

The active biological phytochemicals, crucial compounds employed in creating hundreds of medications, are derived from valuable and medicinally significant plants. These phytochemicals offer excellent protection from various illnesses, including inflammatory disorders and chronic conditions caused by oxidative stress. A phenolic monoterpenoid known as eugenol (EUG), it is typically found in the essential oils of many plant species from the Myristicaceae, Myrtaceae, Lamiaceae, and Lauraceae families. One of the main ingredients of clove oil (Syzygium aromaticum (L.), Myrtaceae), it has several applications in industry, including flavoring food, pharmaceutics, dentistry, agriculture, and cosmeceuticals. Due to its excellent potential for avoiding many chronic illnesses, it has lately attracted attention. EUG has been classified as a nonmutant, generally acknowledged as a safe (GRAS) chemical by the World Health Organization (WHO). According to the existing research, EUG possesses notable anti-inflammatory, antioxidant, analgesic, antibacterial, antispasmodic, and apoptosis-promoting properties, which have lately gained attention for its ability to control chronic inflammation, oxidative stress, and mitochondrial malfunction and dramatically impact human wellness. The purpose of this review is to evaluate the scientific evidence from the most significant research studies that have been published regarding the protective role and detoxifying effects of EUG against a wide range of toxins, including biological and chemical toxins, as well as different drugs and pesticides that produce a variety of toxicities, throughout view of the possible advantages of EUG.

C/EBPβ/AEP is age-dependently activated in Parkinson's disease and mediates α-synuclein in the gut and brain

Parkinson's disease (PD) is the most common neurodegenerative motor disorder, and its pathologic hallmarks include extensive dopaminergic neuronal degeneration in the Substantia nigra associated with Lewy bodies, predominantly consisting of phosphorylated and truncated α-Synuclein (α-Syn). Asparagine endopeptidase (AEP) cleaves human α-Syn at N103 residue and promotes its aggregation, contributing to PD pathogenesis. However, how AEP mediates Lewy body pathologies during aging and elicits PD onset remains incompletely understood. Knockout of AEP or C/EBPβ from α-SNCA mice, and their chronic rotenone exposure models were used, and the mechanism of α-Syn from the gut that spread to the brain was observed. Here we report that C/EBPβ/AEP pathway, aggravated by oxidative stress, is age-dependently activated and cleaves α-Syn N103 and regulates Lewy body-like pathologies spreading from the gut into the brain in human α-SNCA transgenic mice. Deletion of C/EBPβ or AEP substantially diminished the oxidative stress, neuro-inflammation, and PD pathologies, attenuating motor dysfunctions in aged α-SNCA mice. Noticeably, PD pathologies initiate in the gut and progressively spread into the brain. Chronic gastric exposure to a low dose of rotenone initiates Lewy body-like pathologies in the gut that propagate into the brain in a C/EBPβ/AEP-dependent manner. Hence, our studies demonstrate that C/EBPβ/AEP pathway is critical for mediating Lewy body pathology progression in PD.

Introduction of Flavor Chemical Eugenol Attenuating the Synergistic Toxicological Interactions of Flavor Mixtures

The flavor chemicals benzyl alcohol (BEA), phenylethanol (PHA), and cinnamaldehyde (CID) and their binary mixtures have high toxicity sensitivity to the lethal endpoint of Caenorhabditis elegans. Some binary flavor mixtures even have synergistic toxicological interactions. Eugenol (EUG) is closely related to human life and has many special nonlethal effects on organisms. The effect of its introduction on the combined toxicities of flavor mixtures is worth studying. We introduced EUG into three binary (BEA-PHA, BEA-CID, and PHA-CID) and one ternary (BEA-PHA-CID) flavor mixture systems. Five representative mixture rays were selected from each of the four mixture systems using the uniform design ray (UD-Ray) method. The lethal toxicity of each mixture ray to C. elegans was measured at three different exposure volumes (100, 200, and 400 μL), and a dose-effect model was established. The new parameter iSPAN was used to quantitatively characterize the toxicity sensitivity of each chemical and mixture ray. The toxicological interaction of each mixture was evaluated by the toxicological interaction heatmap based on the combination index (CI). It can be seen that all flavor chemicals and their ternary and quaternary mixture rays have high iSPANs, and the highest value is 16.160 (BEA-PHA-CID-EUG-R1 at 400 μL). According to the heatmap and CI, the introduction of EUG attenuates the synergistic toxicological interactions of flavor mixtures, leading to the transformation ofsynergistic interactions in flavor mixtures into additive action and even antagonistic interaction, and the CI value of the antagonistic interaction is up to 1.8494 (BEA-CID-EUG-R4 at 400 μL).

Reactivity vs. selectivity of quinone methides: synthesis of pharmaceutically important molecules, toxicity and biological applications

Quinone methides (QMs) are considered to be highly reactive intermediates because of their aromatization both in chemical and biological systems. Being highly accessible, quinone methides (QMs) have been widely exploited and their concurrent use has been manifested for the synthesis of tertiary and quaternary carbon centers of bioactives, drugs and drug-like molecules. In this feature article, the synthetic routes, structure-reactivity relationships and synthetic applications of quinone methides are discussed. Formation of the intermediates during bioactivation of different chemical entities and possible chemical manifestations leading to their toxicity in biological systems are also covered.

In Vitro PIG-A Gene Mutation Assay in Human B-Lymphoblastoid TK6 Cells

The X-linked PIG-A gene is involved in the biosynthesis of glycosylphosphatidylinositol (GPI) anchors. PIG-A mutant cells fail to synthesize GPI and to express GPI-anchored protein markers (e.g., CD59 and CD55). In recent years, in vitro PIG-A assay has been established based on the high conservation of PIG-A/Pig-a loci among different species and the large data from the in vivo system. The purpose of this study was to extend the approach for PIG-A mutation assessment to in vitro human B-lymphoblastoid TK6 cells by detecting the loss of GPI-linked CD55 and CD59 proteins. TK6 cells were treated with three mutagens 7,12-dimethylbenz[a]anthracene (DMBA), N-ethyl-N-nitrosourea (ENU), etoposide (ETO), and two nonmutagens: cadmium chloride (CdCl2) and sodium chloride (NaCl). The mutation rate of PIG-A gene within TK6 cells was determined on the 11th day with flow cytometry analysis for the negative frequencies of CD55 and CD59. The antibodies used in this production were APC mouse-anti-human CD19 antibody, PE mouse anti-human CD55 antibody, PE mouse anti-human CD59 antibody, and nucleic acid dye 7-AAD. An immunolabeling method was used to reduce the high spontaneous level of preexisting PIG-A mutant cells. Our data suggested that DMBA-, ENU-, and ETO-induced mutation frequency of PIG-A gene was increased by twofold compared with the negative control, and the effects were dose-dependent. However, CdCl2 and NaCl did not significantly increase the mutation frequency of PIG-A gene, with a high cytotoxicity at a dose of 10 mmol/L. Our study suggested that the novel in vitro PIG-A gene mutation assay within TK6 cells may represent a complement of the present in vivo Pig-a assay, and may provide guidance for their potential use in genotoxicity even in cells with a significant deficiency of GPI anchor.

Curry versus cancer: Potential of some selected culinary spices against cancer with in vitro, in vivo, and human trials evidences

Spices are dietary agents with immense potential for cancer chemo-prevention. A wide variety of spices are extensively used as food flavoring agents which possess potent antioxidant, anti-inflammatory, and anticancer properties due to the presence of certain bio-active compounds in them. In vitro, in vivo studies and clinical trials of selected spices against various types of cancer are being specified in this review. Effect of certain putative dietary spices namely turmeric, clove, garlic, ginger, fennel, black cumin, cinnamon, pepper, saffron, rosemary, and chilli along with its role in cancer are being discussed. Literature search was conducted through PubMed, Google scholar, Science direct, and Scopus using the keywords "spice," "cancer," "natural medicine," "herbal compound," "bioactive compounds." About 4,000 published articles and 127 research papers were considered to grab the brief knowledge on spices and their anticancer potential on a predefined inclusion and exclusion criteria. PRACTICAL APPLICATION: Historically, spices and herbs are known for its traditional flavor, odor, and medicinal properties. Intensified risk of chronic and pervasive clinical conditions and increased cost of advanced drug treatments have developed a keen interest among researchers to explore the miscellaneous properties of herbal spices. Cancer is one of the deleterious causes of mortality affecting a huge number of populations worldwide. Arrays of cancer treatments including surgery, chemotherapy, and radiation therapy are used to compromise the disease but effective only when the size of the tumor is small. So, an effective treatment need to be developed that produces less side effects and herbal spices are found to be the promising agents. In this review, we illustrate about different in vitro, in vivo, and clinical studies of wide range of culinary spices having antineoplastic potential.

The Activation of Procarcinogens by CYP1A1/1B1 and Related Chemo-Preventive Agents: A Review

CYP1A1 and CYP1B1 are extrahepatic P450 family members involved in the metabolism of procarcinogens, such as PAHs, heterocyclic amines and halogen-containing organic compounds. CYP1A1/1B1 also participate in the metabolism of endogenous 17-β-estradiol, producing estradiol hydroquinones, which are the intermediates of carcinogenic semiquinones and quinones. CYP1A1 and CYP1B1 proteins share approximately half amino acid sequence identity but differ in crystal structures. As a result, CYP1A1 and CYP1B1 have different substrate specificity to chemical procarcinogens. This review will introduce the general molecular biology knowledge of CYP1A1/1B1 and the metabolic processes of procarcinogens regulated by these two enzymes. Over the last four decades, a variety of natural products and synthetic compounds which interact with CYP1A1/1B1 have been identified as effective chemo-preventive agents against chemical carcinogenesis. These compounds are mainly classified as indirect or direct CYP1A1/1B1 inhibitors based on their distinct mechanisms. Indirect CYP1A1/1B1 inhibitors generally impede the transcription and translation of CYP1A1/1B1 genes or interfere with the translocation of aryl hydrocarbon receptor (AHR) from the cytosolic domain to the nucleus. On the other hand, direct inhibitors inhibit the catalytic activities of CYP1A1/1B1. Based on the structural features, the indirect inhibitors can be categorized into the following groups: flavonoids, alkaloids and synthetic aromatics, whereas the direct inhibitors can be categorized into flavonoids, coumarins, stilbenes, sulfur containing isothiocyanates and synthetic aromatics. This review will summarize the in vitro and in vivo activities of these chemo-preventive agents, their working mechanisms, and related SARs. This will provide a better understanding of the molecular mechanism of CYP1 mediated carcinogenesis and will also give great implications for the discovery of novel chemo-preventive agents in the near future.

Hepatoprotective Role of Berberine on Doxorubicin Induced Hepatotoxicity - Involvement of Cyp

Background:

The liver is one of the major organ involved in drug metabolism. Cytochrome P450s are predominantly involved in drug metabolism. A wide range of CYPs have been reported in the liver which have been involved in its normal as well as in diseased conditions. Doxorubicin, one of the most potent chemotherapeutic drugs, although highly efficacious, also has adverse side effects, with its targets being liver and cardiac tissue.

Objective:

The study aims to evaluate the reversal potentials of berberine on Doxorubicin induced cyp conversion.

Methodology:

In the present study, the interplay between anti-oxidants, cytochrome and inflammatory markers in DOX induced liver toxicity and its possible reversal by berberine was ascertained.

Results:

DOX administration significantly elevated serum as well as tissue stress, which was reverted by berberine treatment. A similar response was observed in tissue inflammatory mediators as well as in serum cytokine levels. Most profound reduction in the cytochrome expression was found in Cyp 2B1, 2B2, and 2E1. However, 2C1, 2C6, and 3A1 although showed a decline, but it did not revert the expression back to control levels.

Conclusion:

It could be concluded that berberine may be an efficient anti-oxidant and immune modulator. It possesses low to moderate cytochrome modulatory potentials.

Induction of EpRE-mediated gene expression by a series of mediterranean botanicals and their constituents

ETHNOPHARMACOLOGICAL RELEVANCE

A variety of Mediterranean plant species, traditionally used for the prevention and treatment of several health conditions, contain ingredients with potential biological activity of which many remain unexplored. Among the beneficial health effects of bioactive phytochemicals is the activation of cellular defense mechanisms involving the activation of EpRE (electrophile responsive element) - mediated changes in gene expression.

AIM OF THE STUDY

The present study aimed to identify botanicals and their active constituents able to activate the EpRE mediated gene expression within a series of Mediterranean plant species known for their hepatoprotective and/or cardioprotective properties.

MATERIALS AND METHODS

Methanolic extracts of 18 botanicals were prepared and tested for their ability to induce gene expression in EpRE-LUX reporter cells. Subsequently, LC-MS (Liquid Chromatography Mass Spectrometry) analysis combined with MAGMa (MS Annotation based on in silico Generated Metabolites) software for automated compound annotation was used to facilitate tentative identification of the active constituents within two of the active extracts. Selected annotated compounds were tested in the EpRE-LUX reporter gene assay followed by definite identification of the most active ones.

RESULTS

It appeared that 9 of the 18 extracts were able to activate EpRE-mediated gene expression. Many active ingredients of the methanolic extracts from Juglans regia and Rhamnus frangula were revealed. Among them, chrysophanol and aloe-emodin were confirmed to be active EpRE inducing ingredients and were definitely identified in the Rhamnus Frangula extract.

CONCLUSIONS

The protective effect of half of the tested botanical varieties via the activation of EpRE-mediated gene expression was confirmed. The study also provided an example of how in vitro bioassays can be combined with LC-MS and the automated chemical annotation software MAGMa, to identify biologically active constituents in complex botanical extracts.

Epigenome modulated xenobiotic detoxification pathways control DMBA-induced breast cancer in agouti Avy/a mice

Environmental xenobiotics with genotoxic activity are carcinogenic. However, individual differences in the susceptibility to xenobiotic-induced breast cancer remain unclear. Since epigenetic modifications could control the expression of metabolic enzymes, our goal was to determine whether epigenome modulated metabolic networks determine susceptibility to xenobiotic-induced breast cancer. The effect of epigenetic background on predisposition to carcinogen 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer development and progression was assessed using the A^vy/a mouse model. In a randomized block design, 22 isogenic A^vy/a (8 yellow, 7 slightly mottled, 7 pseudoagouti) and 8 wild type non-agouti (a/a black) age matched female mice were subjected to DMBA (30 mg/kg per mouse weight) once a week for 6 weeks to induce breast cancer. Compared to pseudoagouti littermates, a significant decrease in tumour latency with increased tumour burden was observed in slightly mottled and yellow littermates (p ≤ 0.05). However, tumour latency and tumour burden were similar in non-agouti a/a mice and A^vy/a cohorts. Network analysis of differentially expressed liver genes identified altered metabolic gene networks among agouti phenotypes. Consequently, in HPLC analyses, DMBA metabolites were significantly increased in A^vy/a pseudoagouti mice (p ≤ 0.05). Relative to A^vy/a slightly mottled, A^vy/a yellow and non-agouti a/a black mice, DMBA metabolites increased nine-, eight-, and four-fold, respectively, in A^vy/a pseudoagouti mice. In agreement with this, seven phase 2 xenobiotic detoxification genes were significantly upregulated in A^vy/a pseudoagouti mice (p ≤ 0.05). The Results from this study suggest that epigenome modulation of xenobiotic detoxification pathways may control xenobiotic-induced breast cancer susceptibility in A^vy/a mice.

Taxifolin Inhibits 7,12-Dimethylbenz(a)anthracene-induced Breast Carcinogenesis by Regulating AhR/CYP1A1 Signaling Pathway

Background:

Breast cancer (BC), because of its invasive characteristics, is one of the most common and deadliest cancers among the female population around the world. Research has demonstrated that AhR signaling also plays a vital role in BC initiation and development as well. Therefore, blocking this pathway to natural interferences paves a new channel for the prevention of BC. Several natural compounds such as flavonoids possess the anticancer activities against different cancers.

Objective:

The present study has been designed to estimate the chemotherapeutic potential of taxifolin (TAX) against 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in Sprague-Dawley rats.

Materials and Methods:

Initially, the molecular docking analysis of AhR and cytochrome P450s (CYPs) (CYP1A1 and CYP1B1) was performed using MAESTRO tool, in an attempt to rationalize the activity of TAX, based on their CYP1-binding potential. The in vitro CYP1A1 activity was determined by luciferase assay with CYP1A1 substrate luciferin CEE. The in vivo analysis was performed by administrating TAX at 10, 20, 40 mg/kg BW for 28 days intragastrically in DMBA induced (25 mg/animal dose) at 55 days of age Sprague-Dawley (SD) rats. BC initiates after 90 days of tumor induction phase. The molecular mechanism of TAX on Ahr and CYPs was also examined through the mRNA and protein expressions using reverse transcription-quantitative polymerase chain reaction and Western blotting analysis.

Results:

Furthermore, TAX altered the energy regulation on DMBA-induced BC in SD rats by considerably restoring the cancer-induced modulations in tumor growth. Our results showed that TAX reduced the expressions of CYP1A1 and CYP1B1 in DMBA-induced mammary carcinoma by downregulating the AhR signaling pathway.

Conclusion:

This study revealed that TAX might be able to act as a chemotherapeutic agent against CYP1A1- and CYP1B1-mediated cancer and the inhibition of the DMBA-induced mammary carcinogenesis in a rat model.

Abbreviations used: CYPs: Cytochrome P450s; PAH: polycyclic aromatic hydrocarbons; HRP- Horseradish peroxidase; BSA: Bovine serum albumin; DTTP: Deoxythymidine Triphosphate (nucleotide); RT-qPCR: Real Time quantitative polymerase chain reaction; CADD: Computer Aided Drug Drafting.

The Dual Antioxidant/Prooxidant Effect of Eugenol and Its Action in Cancer Development and Treatment

The formation of reactive oxygen species (ROS) during metabolism is a normal process usually compensated for by the antioxidant defense system of an organism. However, ROS can cause oxidative damage and have been proposed to be the main cause of age-related clinical complications and diseases such as cancer. In recent decades, the relationship between diet and cancer has been more studied, especially with foods containing antioxidant compounds. Eugenol is a natural compound widely found in many aromatic plant species, spices and foods and is used in cosmetics and pharmaceutical products. Eugenol has a dual effect on oxidative stress, which can action as an antioxidant or prooxidant agent. In addition, it has anti-carcinogenic, cytotoxic and antitumor properties. Considering the importance of eugenol in the area of food and human health, in this review, we discuss the role of eugenol on redox status and its potential use in the treatment and prevention of cancer.

Molecular effects of hesperetin, a citrus flavanone on7,12-dimethylbenz(a)anthracene induced buccal pouch squamous cell carcinoma in golden Syrian hamsters

In recent years, researchers have been focused on citrus flavanone, a naturally occurring bioactive substance of hesperetin. To investigate the molecular mechanism based chemopreventive efficacy of hesperetin on 7,12-dimethylbenz(a)anthracene (DMBA) induced hamster buccal pouch (HBP) squamous cell carcinoma (SCC). The oral tumour was provoked by painted with 0.5% DMBA on left buccal pouch thrice a week for 10 consecutive weeks developed well-differentiated SCC and tumour formation was 100% in DMBA alone. We evaluated the chemopreventive potential of hesperetin by assessing the lipid peroxidation (LPO) by-products, status of enzymatic, non-enzymatic antioxidants, detoxifying agents etc. Moreover, modulating expression of apoptotic and cell proliferation markers were observed in HBP SCC experimental hamsters. Oral administration of hesperetin (20 mg/kg b.w.) to DMBA painted hamsters significantly reversed the stages of oral SCC. Our findings indicate that hesperetin possesses a chemopreventive effect in DMBA-induced oral SCC by exerting anti-carcinogenic property.

Pharmacological and Toxicological Properties of Eugenol

Eugenol is a volatile phenolic constituent of clove essential oil obtained from Eugenia caryophyllata buds and leaves. It is a functional ingredient of numerous products which have been used in the pharmaceutical, food and cosmetic industry in restricted concentrations. Its derivatives have been used in medicine as a local antiseptic and anesthetic. The wide range of eugenol activities includes antimicrobial, anti-inflammatory, analgesic and antioxidant. Although eugenol is considered safe as a product, due to the vast range of different applications and extensive use, there has been a great concern about its toxicity in recent years. However, studies about cytotoxicity and genotoxicity of eugenol are very limited and controversial. The pharmacological and toxicological properties of eugenol will be discussed in this review.

Chemosensitivity of MCF-7 cells to eugenol: release of cytochrome-c and lactate dehydrogenase

Phytochemicals have been extensively researched for their potential anticancer effects. In previous study, direct exposure of rat liver mitochondria to eugenol main ingredient of clove, uncoupled mitochondria and increased F₀F₁ATPase activity. In the present study, we further investigated the effects of eugenol on MCF-7 cells in culture. Eugenol demonstrated: a dose-dependent decrease in viability (MTT assay), and proliferation (real time cell analysis) of MCF-7 cells, (EC₅₀: 0.9 mM); an increase in reactive oxygen species; a decrease in ATP level and mitochondrial membrane potential (MitoPT JC-1 assay); and a release of cytochrome-c and lactate dehydrogenase (Cytotoxicity Detection Kit ^PLUS) into culture media at eugenol concentration >EC₅₀. Pretreatment with the antioxidants Trolox and N-acetyl cysteine partially restored cell viability and decreased ROS, with Trolox being more potent. Expression levels of both anti- and pro-apoptotic markers (Bcl-2 and Bax, respectively) decreased with increasing eugenol concentration, with no variation in their relative ratios. Eugenol-treated MCF-7 cells overexpressing Bcl-2 exhibited results similar to those of MCF-7. Our findings indicate that eugenol toxicity is non-apoptotic Bcl-2 independent, affecting mitochondrial function and plasma membrane integrity with no effect on migration or invasion. We report here the chemo-sensitivity of MCF-7 cells to eugenol, a phytochemical with anticancer potential.

Protective Effects of Essential Oils as Natural Antioxidants against Hepatotoxicity Induced by Cyclophosphamide in Mice

Clinical application of cyclophosphamide (CP) as an anticancer drug is often limited due to its toxicity. CP is metabolized mainly in the liver by cytochrome P450 system into acrolein which is the proximate toxic metabolite. Many different natural antioxidants were found to alleviate the toxic effects of various toxic agents via different mechanisms. Therefore, the present study aimed at investigating the role of essential oils extracted from fennel, cumin and clove as natural antioxidants in the alleviation of hepatotoxicity induced by CP through assessment of hepatotoxicity biomarkers (AST, ALT, ALP), histopathology of liver tissues as well as other biochemical parameters involved in the metabolism of CP. The data of the present study showed that treatment of male mice with cyclophosphamide (2.5 mg/Kg BW) as repeated dose for 28 consecutive days was found to induce hepatotoxicity through the elevation in the activities of AST, ALT, and ALP. Combined administration of any of these oils with CP to mice partially normalized the altered hepatic biochemical markers caused by CP, whereas administration of fennel, clove or cumin essential oils alone couldn't change liver function indices. Moreover, CP caused histological changes in livers of mice including swelling and dilation in sinusoidal space, inflammation in portal tract and hepatocytes, as well as, hyperplasia in Kuppfer cells. However, co-administration of any of the essential oils with CP alleviated to some extent the changes caused by CP but not as the normal liver. CP was also found to induce free radical levels (measured as thiobarbituric acid reactive substances) and inhibited the activities of superoxide dismutase, glutathione reductase, and catalase as well as activities and protein expressions of both glutathione S-transferase (GSTπ) and glutathione peroxidase. Essential oils restored changes in activities of antioxidant enzymes (SOD, CAT, GR, GST, and GPx) caused by CP to their normal levels compared to control group. In addition, treatment of mice with CP was found to induce the protein expression of CYP 3A4, 2B1/2, 2C6, 2C23. Moreover, the present study showed that essential oils reduced the expression of CYPs 2E1, 3A4 but could not restore the expression of CYP 2C6 and 2C23 compared to CP-treated mice. Interestingly, pretreatment of mice with essential oil of clove was found to restore activities of DMN-dI, AHH, and ECOD which were induced by CP to their normal control levels. It is concluded that EOs showed a marked hepatoprotective effect against hepatotoxicity induced by CP. In addition, co-administration of CP with any of these oils might be used as a new strategy for cancer treatment to alleviate the hepatotoxicity induced by CP.

Use of Polyphenolic Compounds in Dermatologic Oncology

Polyphenols are a widely used class of compounds in dermatology. While phenol itself, the most basic member of the phenol family, is chemically synthesized, most polyphenolic compounds are found in plants and form part of their defense mechanism against decomposition. Polyphenolic compounds, which include phenolic acids, flavonoids, stilbenes, and lignans, play an integral role in preventing the attack on plants by bacteria and fungi, as well as serving as cross-links in plant polymers. There is also mounting evidence that polyphenolic compounds play an important role in human health as well. One of the most important benefits, which puts them in the spotlight of current studies, is their antitumor profile. Some of these polyphenolic compounds have already presented promising results in either in vitro or in vivo studies for non-melanoma skin cancer and melanoma. These compounds act on several biomolecular pathways including cell division cycle arrest, autophagy, and apoptosis. Indeed, such natural compounds may be of potential for both preventive and therapeutic fields of cancer. This review evaluates the existing scientific literature in order to provide support for new research opportunities using polyphenolic compounds in oncodermatology.

Citral and eugenol modulate DNA damage and pro-inflammatory mediator genes in murine peritoneal macrophages

Citral and eugenol have been broadly studied because of their anti-inflammatory, antioxidant and antiparasitic potentials. In this study, the effects of citral (25, 50 and 100 µg/mL) and eugenol (0.31, 0.62, 1.24 and 2.48 µg/mL) on the expression (RT-PCR) of the pro-inflammatory mediator genes NF-κB1, COX-2 and TNF-α were evaluated in mouse peritoneal macrophages with or without activation by a bacterial lipopolysaccharide (LPS). Additionally, the genotoxic potentials of two compounds and their capacities to modulate the DNA damage induced by doxorubicin (DXR) were investigated using the comet assay. The data revealed that neither citral nor eugenol changed COX-2, NF-κB1 or TNF-α expression in resting macrophages. However, in LPS-activated cells, citral induced the hypoexpression of COX-2 (100 µg/mL) and TNF-α (50 and 100 µg/mL). Hypoexpression of TNF-α was also detected after cellular exposure to eugenol at the highest concentration (2.48 µg/mL). Both compounds exhibited genotoxic potential (citral at 50 and 100 µg/mL and eugenol at all concentrations) but also showed chemopreventive effects, in various treatment protocols. Both citral and eugenol might modulate inflammatory processes and DXR-induced DNA damage, but the use of these compounds must be viewed with caution because they are also able to induce primary DNA lesions.

Safety evaluation of a triazine compound nitromezuril by assessing bacterial reverse mutation, sperm abnormalities, micronucleus and chromosomal aberration

Nitromezuril (NZL) is a novel triazine compound that exhibits remarkable anticoccidial activity. However, mutagenicity and genotoxicity of NZL have not been evaluated to date. This study evaluated the potential risks of NZL by testing for bacterial reverse mutation (Ames), mouse sperm abnormality (SA), bone marrow micronucleus (MN) and chromosomal aberration (CA). Mice were orally administered with NZL at 385, 192 and 96 mg/kg, corresponding to 0.5 ×, 0.25 × and 0.125 × the LD50 of NZL, respectively. No significant increases in SA and CA were found in mice treated with NZL for 5d and 3d, respectively (P>0.05). NZL at 96-385 mg/kg did not have significant influence on micronucleated polychromatic erythrocyte counts (P>0.05). These results suggest that NZL is not genotoxic. However, Ames test results were positive both with and without the S9 system for Salmonella typhimurium TA98 and TA100, suggesting that NZL may be mutagenic. The mutagenic effects of NZL were different in in vitro and in vivo assays. Further studies should be conducted to confirm the safety of using and developing NZL as a novel anticoccidial drug.

Eugenol-rich Fraction of Syzygium aromaticum (Clove) Reverses Biochemical and Histopathological Changes in Liver Cirrhosis and Inhibits Hepatic Cell Proliferation

Background:

Dried flower bud of Syzygium aromaticum (clove) is rich in eugenol, an antioxidant and antiinflammatory compound that can protect liver against injury. Clove, besides eugenol, also contains other pharmacologically active phytochemicals such as β-sitosterol and ascorbic acid. This study reports the effect of eugenol-rich fraction (ERF) of clove on liver cirrhosis induced by thioacetamide.

Methods:

Cirrhosis of the liver, which predisposes to hepatocellular carcinoma, was induced by administering thioacetamide (0.03%) in drinking water for 16 weeks. Cirrhotic animals were divided into two groups; the treated group was administered ERF for 9 weeks, one week after discontinuation of thioacetamide, while the other group received normal saline for a similar duration of time.

Results:

The treatment with ERF, as determined by histopathology and through a battery of biochemical markers of hepatic injury, oxidative stress and drug metabolizing enzymes, significantly ameliorated the signs of liver cirrhosis. It lowered the elevated levels of alkaline phosphatase, γ-glutamyl transferase and other biochemical changes in liver cirrhosis. Histopathology of the liver corroborated the effect of ERF with biochemical findings. ERF treatment further inhibited cell proliferation, as demonstrated by reduced [³H]-thymidine uptake.

Conclusions:

Data provide evidence supporting the protective action of ERF on liver cirrhosis. The study assumes significance because cirrhosis predisposes the liver to cancer, which is characterized by abnormal cell proliferation. ERF in this study is reported to inhibit hepatic cell proliferation and at the same time decrease oxidative stress, which might be the mechanism of protection against liver cirrhosis.

Safety Evaluation of Chrysanthemum indicum L. Flower Oil by Assessing Acute Oral Toxicity, Micronucleus Abnormalities, and Mutagenicity

Chrysanthemum indicum is widely used to treat immune-related and infectious disorders in East Asia. C. indicum flower oil contains 1,8-cineole, germacrene D, camphor, α-cadinol, camphene, pinocarvone, β-caryophyllene, 3-cyclohexen-1-ol, and γ-curcumene. We evaluated the safety of C. indicum flower oil by conducting acute oral toxicity, bone marrow micronucleus, and bacterial reverse mutation tests. Mortality, clinical signs and gross findings of mice were measured for 15 days after the oral single gavage administration of C. indicum flower oil. There were no mortality and clinical signs of toxicity at 2,000 mg/kg body weight/day of C. indicum flower oil throughout the 15 day period. Micronucleated erythrocyte cell counts for all treated groups were not significantly different between test and control groups. Levels of 15.63~500 μg C. indicum flower oil/plate did not induce mutagenicity in S. Typhimurium and E. coli, with or without the introduction of a metabolic activation system. These results indicate that ingesting C. indicum flower oil produces no acute oral toxicity, bone marrow micronucleus, and bacterial reverse mutation.

Quinone Methide Bioactivation Pathway: Contribution to Toxicity and/or Cytoprotection?

The formation of quinone methides (QMs) from either direct 2-electron oxidation of 2- or 4-alkylphenols, isomerization of o-quinones, or elimination of a good leaving group could explain the cytotoxic/cytoprotective effects of several drugs, natural products, as well as endogenous compounds. For example, the antiretroviral drug nevirapine and the antidiabetic agent troglitazone both induce idiosyncratic hepatotoxicity through mechanisms involving quinone methide formation. The anesthetic phencyclidine induces psychological side effects potentially through quinone methide mediated covalent modification of crucial macromolecules in the brain. Selective estrogen receptor modulators (SERMs) such as tamoxifen, toremifene, and raloxifene are metabolized to quinone methides which could potentially contribute to endometrial carcinogenic properties and/or induce detoxification enzymes and enhance the chemopreventive effects of these SERMs. Endogenous estrogens and/or estrogens present in estrogen replacement formulations are also metabolized to catechols and further oxidized to o-quinones which can isomerize to quinone methides. Both estrogen quinoids could cause DNA damage which could enhance hormone dependent cancer risk. Natural products such as the food and flavor agent eugenol can be directly oxidized to a quinone methide which may explain the toxic effects of this natural compound. Oral toxicities associated with chewing areca quid could be the result of exposure to hydroxychavicol through initial oxidation to an o-quinone which isomerizes to a p-quinone methide. Similar o-quinone to p-quinone methide isomerization reactions have been reported for the ubiquitous flavonoid quercetin which needs to be taken into consideration when evaluating risk-benefit assessments of these natural products. The resulting reaction of these quinone methides with proteins, DNA, and/or resulting modulation of gene expression may explain the toxic and/or beneficial effects of the parent compounds.

Modulation of carcinogen-metabolizing cytochromes P450 by phytochemicals in humans

INTRODUCTION

Cytochrome P450 (CYP) families 1 - 3, besides oxidizing environmental and dietary chemicals, leading to their elimination, catalyze the bioactivation of exogenous as well as endogenous carcinogens. Phytochemicals, particularly those which are active food components, were shown to be able to affect specific CYP expression and/or activity in animal models and in human in vitro systems. Human intervention studies involving healthy volunteers were also performed. This review describes human CYP modulation by naturally occurring phytochemicals which can not only affect carcinogen metabolism in humans, but also change the drug response.

AREAS COVERED

The authors present an overview of carcinogens metabolizing human CYP modulation in different model systems as well as studies on human dietary intervention. Furthermore, the authors provide examples of the phytochemicals that affect CYP expression and activity.

EXPERT OPINION

CYP, which are involved in carcinogen activation, can metabolize a range of substrates and inducing CYP by one substrate may also increase the metabolism of another. The ultimate proof of the efficacy of CYP modulation strategy for chemoprevention may be provided by clinical trials involving risk populations, which are difficult to perform. The new human-like models are highly desired for the study of modulation of carcinogen-metabolizing CYP.

Evaluation of the effect of beetroot juice on DMBA-induced damage in liver and mammary gland of female Sprague-Dawley rats

Red beetroot contains a specific class of antioxidants collectively named betalains, which have been shown to have anticarcinogenic and anti-inflamatory potential. We investigated the effect of beetroot juice on the hepatic and mammary gland carcinogen metabolizing enzymes, DNA damage and liver injury, altered by 7,12-dimethylbenz[a]anthracene (DMBA). In the liver, pretreatment with beetroot juice significantly decreased levels and activities of the majority of tested biochemical parameters, elevated by DMBA. Feeding with beetroot juice decreased the activities of CYP1A1 and 1A2 and increased phase II enzymes. The activities of all enzymes tested were enhanced in the animals treated with DMBA alone and in combination with beetroot juice. The most significant changes in the level of the enzymes tested were observed for

NAD(P)H

quinone oxidoreductase-1. In mammary gland, beetroot juice induced the level of glutathione S-transferase pi, enzyme involved in active metabolites of DMBA detoxification. The final effects of beetroot juice are tissue specific and depend on the class of carcinogen.

Non-animal test methods for predicting skin sensitization potentials

Contact allergies are complex diseases, and it is estimated that 15-20 % of the general population suffers from contact allergy, with increasing prevalence. Evaluation of the sensitization potential of a substance is usually carried out in animal models. Nowadays, there is much interest in reducing and ultimately replacing current animal tests. Furthermore, as of 2013, the EU has posed a ban on animal testing of cosmetic ingredients that includes skin sensitization. Therefore, predictive and robust in vitro tests are urgently needed. In order to establish alternatives to animal testing, the in vitro tests must mimic the very complex interactions between the sensitizing chemical and the different parts of the immune system. This review article summarizes recent efforts to develop in vitro tests for predicting skin sensitizers. Cell-based assays, in chemico methods and, to a lesser extent, in silico methods are presented together with a discussion of their current status. With considerable progress having been achieved during the last years, the rationale today is that data from different non-animal test methods will have to be combined in order to obtain reliable hazard and potency information on potential skin sensitizers.

Antiproliferative and molecular mechanism of eugenol-induced apoptosis in cancer cells

Phenolic phytochemicals are a broad class of nutraceuticals found in plants which have been extensively researched by scientists for their health-promoting potential. One such a compound which has been comprehensively used is eugenol (4-allyl-2-methoxyphenol), which is the active component of Syzigium aromaticum (cloves). Aromatic plants like nutmeg, basil, cinnamon and bay leaves also contain eugenol. Eugenol has a wide range of applications like perfumeries, flavorings, essential oils and in medicine as a local antiseptic and anesthetic. Increasing volumes of literature showed eugenol possesses antioxidant, antimutagenic, antigenotoxic, anti-inflammatory and anticancer properties. Molecular mechanism of eugenol-induced apoptosis in melanoma, skin tumors, osteosarcoma, leukemia, gastric and mast cells has been well documented. This review article will highlight the antiproliferative activity and molecular mechanism of the eugenol induced apoptosis against the cancer cells and animal models.

Impact of eugenol and isoeugenol on AhR translocation, target gene expression, and proliferation in human HaCaT keratinocytes

The phenolic derivatives eugenol and isoeugenol, which are naturally found in essential oils of different spices, are commonly used as fragrances. Recently data demonstrated that growth suppression produced by these substances occurs in keratinocytes and that the effects may be mediated via aryl hydrocarbon receptor (AhR) interactions. In this study the effects of eugenol and isoeugenol were determined on intracellular localization of AhR, AhR target gene expression, AhR-dependent cell cycle regulation, and proliferation in HaCaT cells. Both compounds produced a rapid and marked translocation of AhR into the nucleus, induced the expression of the AhR target genes cytochrome P-450 1A1 (CYP1A1) and AhR repressor (AhRR), and inhibited proliferation of HaCaT cells. Among the G(1) phase cell cycle-related proteins, levels of the retinoblastoma protein (RB), which is known to interact with AhR, and levels of the cyclin dependent kinase (CDK) 6 were reduced by eugenol and isoeugenol, whereas steady-state levels of CDK2 and CDK4 remained unaffected. Protein levels of CDK inhibitor (CKI) p27(KIP1), known to be modulated in an AhR-dependent manner, were increased after treatment with both substances. In conclusion, data show that the antiproliferative properties of eugenol and isoeugenol in HaCaT cells are mediated through AhR, and thereby the molecular mechanisms of action in these cells were identified for the first time in this study.

Cross talk between keratinocytes and dendritic cells: impact on the prediction of sensitization

Understanding the mechanistic aspects involved in sensitization by chemicals will help to develop relevant preventive strategies. Many potential sensitizers are not directly immunogenic but require activation outside or inside the skin by nonenzymatic oxidation (prehaptens) or metabolic transformation (prohaptens) prior to being able to induce an immune response. This necessary activation step has not yet been actively integrated into a cell line-based prediction approach. We cocultured HaCaT keratinocytes with THP-1 as dendritic cell-like cells allowing intercellular interactions. The sensitizing potential was determined by analyzing differences in the expression of CD86, CD40, and CD54 on cocultured THP-1 cells. This new assay setup allowed (1) to distinguish irritants from allergens without influencing cell viability and (2) to discriminate pre/prohaptens from haptens. Under coculture conditions, the prohaptens eugenol, 2-methoxy-4-methylphenol, and benzo[a]pyrene induced a significantly higher upregulation of CD86 expression on THP-1. In agreement with the hapten concept, responses to 2,4-dinitrochlorobenzene, Bandrowski's base, and the prehapten isoeugenol were not significantly modified. Inhibition of cytochrome P450 or NAD(P)H:quinone oxidoreductase (NQO1) activity reduced the prohapten-mediated upregulation of CD86 on cocultured THP-1 cells. This coculture assay allowing cross talk between HaCaT and THP-1 cells appears to be suitable for the detection of prohaptens, is reproducible, easy to perform, and avoids donor variations. In addition, this assay is a promising approach to understand the impact of cross talk on the prediction of sensitization and once established may be integrated in a future in vitro toolbox to detect potential skin sensitizers and may thus contribute to reduce animal testing.

Antigenotoxic effect of genistein against 7,12-dimethylbenz[a]anthracene induced genotoxicity in bone marrow cells of female Wistar rats

Carcinogen induced mutation in somatic cells leads to genetic instability, which is considered as an important facet of carcinogenesis. Agents that inhibit DNA adduct formation, stimulate DNA repair mechanisms, and possess antioxidant functions are considered as antigenotoxic agents. Genistein, the major isoflavone of soy products, protects animals against experimentally induced mammary and prostate cancers. 7,12-Dimethylbenz[a]anthracene (DMBA), a potent site-specific carcinogen, induce mutations in DNA through its active metabolite, dihydrodiol epoxide, what is a crucial step in cancer initiation. The antigenotoxic effect of genistein against DMBA-induced genotoxicity has been investigated in the present study by analyzing the frequency of micronucleated polychromatic erythrocytes (MnPCEs) and chromosomal aberrations as cytogenetic end-points. The status of lipid peroxidation, antioxidants and detoxication agents were used as biochemical end-points to assess the antigenotoxic effect of genistein. Elevated MnPCEs frequency, marked chromosomal aberrations and enhanced status of lipid peroxidation, antioxidants and detoxication agents were observed in DMBA-treated animals. Oral pretreatment of genistein (20 mg/kg b.w.) for 5 days to DMBA-treated animals significantly reduced the frequency of micronucleus formation and chromosomal abnormalities as well as reversed the status of biochemical variables. Our results suggest that genistein has potent antigenotoxic effect against DMBA-induced genotoxicity.

HMOX1 and NQO1 genes are upregulated in response to contact sensitizers in dendritic cells and THP-1 cell line: role of the Keap1/Nrf2 pathway

Electrophilicity is one of the most common features of skin contact sensitizers and is necessary for protein haptenation. The Keap1 (Kelch-like ECH-associated protein 1)/Nrf2 -signaling pathway is dedicated to the detection of electrophilic stress in cells leading to the upregulation of genes involved in protection or neutralization of chemical reactive species. Signals provided by chemical stress could play an important role in dendritic cell activation and the aim of this work was to test whether contact sensitizers were specific activators of the Keap1/Nrf2 pathway. CD34-derived dendritic cells (CD34-DC) and the THP-1 myeloid cell line were treated by a panel of sensitizers (Ni, 1-chloro 2,4-dinitrobenzene, cinnamaldehyde, 7-hydroxycitronellal, 1,4-dihydroquinone, alpha-methyl-trans-cinnamaldehyde, 2-4-tert-(butylbenzyl)propionaldehyde or Lilial, and 1,4-phenylenediamine), irritants (sodium dodecyl sulfate, benzalkonium chloride), and a nonsensitizer molecule (chlorobenzene). Three well-known Nrf2 activators (tert-butylhydroquinone, lipoic acid, sulforaphane) were also tested. Expression of hmox1 and nqo1 was measured using real-time PCR and cellular accumulation of Nrf2 was assessed by Western blot. Our results showed an increased expression at early time points of hmox1 and nqo1 mRNAs in response to sensitizers but not to irritants. Accumulation of the Nrf2 protein was also observed only with chemical sensitizers. A significant inhibition of the expression of hmox1 and nqo1 mRNAs and CD86 expression was found in 1-chloro 2,4-dinitrobenzene-treated THP-1 cells preincubated with N-acetyl cysteine, a glutathione precursor. Altogether, these data suggested that the Keap1/Nrf2-signaling pathway was activated by electrophilic molecules including sensitizers in dendritic cells and in the THP-1 cell line. Monitoring of this pathway may provide new biomarkers (e.g., Nrf2, hmox1) for the detection of the sensitization potential of chemicals.

Antigenotoxic effect of ferulic acid in 7,12-dimethyl benz(a)-anthracene (DMBA) induced genotoxicity

The antigenotoxic effect of ferulic acid was carried out by evaluating the cytogenetic markers, the micronuclei frequency and chromosomal aberrations, in the bone marrow of hamsters in 7,12-dimethylbenz(a)anthracene (DMBA) induced genotoxicity. Genotoxicity was induced in experimental hamsters by single intraperitoneal injection of DMBA (30 mg kg(-1) b.w.). Pretreatment of ferulic acid orally at a dose of 40 mg kg(-1) b.w. for five days significantly reduced the frequency of micronucleated polychromatic erythrocytes (MnPCEs) and the percentage of chromosomal aberrations in hamster's bone marrow. Our results thus suggest that ferulic acid has potent antigenotoxic effect in DMBA induced genotoxicity in golden Syrian hamsters.