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PubMed2004

Eugenol as an in vivo radioprotective agent.

In the present work, an attempt has been made to evaluate the possible in vivo radioprotection by eugenol. Swiss albino mice were administered different doses of eugenol (75,150 and 300 mg/kg) before exposure to 1.5 Gy of gamma radiation. The micronucleus test was carried out to determine the genetic damage in bone marrow. Our results demonstrated significant reduction in the frequencies of micronucleated polychromatic erythrocytes (MnPCEs) with all three eugenol doses. Eugenol (150 mg/kg) was also tested against different doses of radiation (0.5, 1, 1.5, and 2 Gy) and was found to afford significant radioprotection. Reduction in the incidence of MnPCEs could be noticed up to 72 h postirradiation (1.5 Gy). Moreover, the level of peroxidative damage and the specific activities of lactate dehydrogenase (LDH) and methylglyoxalase I (Gly I) were observed in the liver of mice treated with eugenol for seven days in comparison to untreated mice. The results revealed that eugenol exerted significant protection against oxidative stress. This possibility was further supported by the enhanced response of Gly I and the lowered activity of LDH. The present findings suggested that eugenol has a radioprotective potential.

Animals↗
PubMed2006

Use of biomonitoring data to evaluate methyl eugenol exposure.

Methyl eugenol is a naturally occurring material found in a variety of food sources, including spices, oils, and nutritionally important foods such as bananas and oranges. Given its natural occurrence, a broad cross-section of the population is likely exposed. The availability of biomonitoring and toxicology data offers an opportunity to examine how biomonitoring data can be integrated into risk assessment. Methyl eugenol has been used as a biomarker of exposure. An analytical method to detect methyl eugenol in human blood samples is well characterized but not readily available. Human studies indicate that methyl eugenol is short-lived in the body, and despite the high potential for exposure through the diet and environment, human blood levels are relatively low. The toxicology studies in animals demonstrate that relatively high-bolus doses administered orally result in hepatic neoplasms. However, an understanding is lacking regarding how this effect relates to the exposures that result when food containing methyl eugenol is consumed. Overall, the level of methyl eugenol detected in biomonitoring studies indicates that human exposure is several orders of magnitude lower than the lowest dose used in the bioassay. Furthermore, there are no known health effects in humans that result from typical dietary exposure to methyl eugenol.

Animals↗
PubMed2000

Methyl eugenol and cue-lure traps for suppression of male oriental fruit flies and melon flies (Diptera: Tephritidae) in Hawaii: effects of lure mixtures and weathering.

Methyl eugenol (4-allyl-1,2-dimethoxybenzene-carboxylate) and cue-lure [4-(p-acetoxyphenyl)-2-butanone] are highly attractive kairomone lures to oriental fruit fly, Bactrocera dorsalis (Hendel), and melon fly, B. cucurbitae (Coquillett), respectively. Plastic bucket traps were evaluated as dispensers for methyl eugenol and cue-lure for suppression of the 2 fruit flies in Hawaii. Methyl eugenol and cue-lure mixtures were compared with pure methyl eugenol or cue-lure over 4 seasons. B. dorsalis captures differed significantly with treatment and season. B. dorsalis captures with 100% methyl-eugenol were significantly greater than all other treatments (25, 50, and 75%). B. cucurbitae captures also differed significantly with treatment but not with season. Captures with 100, 75, and 50% cue-lure were not significantly different. Bucket traps baited with cue-lure (+ malathion) and weathered under Hawaiian climatic conditions were attractive to B. cucurbitae up to 8 wk. Two methyl eugenol dispensers (canec disks and Min-U-Gel) were compared with bucket traps. Dispensers (methyl eugenol + malathion) were weathered for 2-16 wk under Hawaiian climatic conditions and bioassayed during summer and winter. Initially, captures of B. dorsalis were not significantly different for the 3 dispensers. Bucket traps and canec disks were most resistant to weather, remaining attractive to B. dorsalis flies up to 16 wk. Min-U-Gel was least resistant, losing attractiveness to B. dorsalis flies within 2 wk. On the basis of performance, bucket traps and canec disks were equally long-lived up to 14 wk; thereafter, bucket traps were slightly more attractive during winter. Canec disks were cheapest, but on the basis of possible environmental concerns, bucket traps may be the best all-around choice for areawide suppression of fruit flies.

Animals↗
PubMed1999

Antioxidant effect of eugenol in rat intestine.

The effect of eugenol on the antioxidant status of the rat intestine after short and long term (15 days and 90 days respectively) oral administration of 1000 mg/kg.b.wt (a dosage which has been reported to be highly hepatoprotective) was studied. The level of lipid peroxidation products (TBARS) and the activities of glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) were found to be near normal on eugenol treatment. The level of glutathione (GSH) did not show any change on 15 days of eugenol treatment, but it was increased significantly on 90 day eugenol treatment. The activity of glutathione-S-transferases (GSTs) was increased significantly in both 15 day eugenol treated and 90-day eugenol treated groups. The results suggest that eugenol is nontoxic, protective and induces glutathione-S-transferases (GSTs) and thereby it may facilitate the removal of toxic substances from the intestine.

Animals↗
PubMed2006

Influence of eugenol-containing temporary cement on bonding of self-etching adhesives to dentin.

PURPOSE: To investigate the influence of eugenol-containing temporary cement on bonding of resin composite to dentin mediated by self-etching adhesives. MATERIALS AND METHODS: Flat dentin surfaces were produced by grinding of extracted human molars. The dentin surfaces were either used directly or after a one-week exposure to a zinc oxide-eugenol cement (IRM). A resin composite (Herculite XRV) was bonded to the dentin surfaces following treatment with 1 of 6 self-etching adhesives (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, iBond, OptiBond Solo Plus - Self-Etch Adhesive System, and Xeno III). An adhesive system containing 0.5 M EDTA as dentin conditioner (Gluma Classic) was included as negative control, and an etch-and-rinse adhesive system (OptiBond FL) was included as positive control. After storage in water at 37 degrees C for 1 week, the bonded specimens were fractured in shear (n = 8 in each group). RESULTS: Previous contact of dentin with zinc oxide-eugenol cement significantly decreased the bond strength mediated by the negative control and did not affect the bond strength mediated by the positive control. For the self-etching adhesives, no effect was found of previous contact with zinc oxide-eugenol cement. With and without previous contact with zinc oxide-eugenol cement, the etch-and-rinse adhesive system yielded a significantly higher bond strength than all other adhesive systems. CONCLUSION: Previous contact with zinc oxide-eugenol cement did not decrease the bond strength of resin composite to dentin mediated by self-etching adhesives. This finding suggests that eugenol-containing temporary cements may be safe to use in combination with self-etching adhesives.

Analysis of Variance↗
PubMed1989

Peroxidase-catalyzed oxidation of eugenol: formation of a cytotoxic metabolite(s).

The oxidation of eugenol (4-allyl-2-methoxyphenol) by horseradish peroxidase was studied. Following the initiation of the reaction with hydrogen peroxide, eugenol was oxidized via a one-electron pathway to a phenoxyl radical which subsequently formed a transient, yellow-colored intermediate which was identified as a quinone methide. The eugenol phenoxyl radical was detected using fast-flow electron spin resonance. The radicals and/or quinone methide further reacted to form an insoluble complex polymeric material. The stoichiometry of the disappearance of eugenol versus hydrogen peroxide was approximately 2:1. The addition of glutathione or ascorbate prevented the appearance of the quinone methide and also prevented the disappearance of the parent compound. In the presence of glutathione, a thiyl radical was detected, and increases in oxygen consumption and in the formation of oxidized glutathione were also observed. These results suggested that glutathione reacted with the eugenol phenoxyl radical and reduced it back to the parent compound. Glutathione also reacted directly with the quinone methide resulting in the formation of a eugenol-glutathione conjugate(s). Using 3H-labeled eugenol, extensive covalent binding to protein was observed. Finally, the oxidation products of eugenol/peroxidase were observed to be highly cytotoxic using isolated rat hepatocytes as target cells.

Animals↗
PubMedDate not supplied

Interaction between eugenol-related compounds and radicals.

The radical modulating activity of 2-methoxy-4-(2-propenyl)phenol (eugenol), 2-t-butyl-4-methoxy-phenol (BHA), and their dimers (bis-eugenol, bis-BHA) was investigated, using ESR spectroscopy. Eugenol produced radicals in alkaline solutions, and enhanced the radical intensity of both sodium-L-ascorbate and sodium 5,6-benzylidene-L-ascorbate. BHA has similar, but slightly lower activity, and their dimers were inactive. Their ability to scavenge the superoxide anion (O2-), generated by hypoxanthine and xanthine oxidase reaction, was in the order of eugenol > bis-eugenol > BHA > bis-BHA. The relative radical intensity among these compounds was paralleled by their cytotoxic activity. The present study demonstrates that eugenol and BHA were very reactive with radicals and their reactivity was considerably reduced by dimerization. The applicability of the dimerized eugenol in dentistry was discussed.

Ascorbic Acid↗
PubMed2001

Effects of eugenol on resin bond strengths to root canal dentin.

The purpose of this study was to compare the regional bond strengths of C&B Metabond resin to root canal dentin, with or without treatment using a eugenol-containing endodontic sealer liquid. Eighteen extracted human canines were decoronated at the cementoenamel junction with a slow speed saw. The apical third of the root was removed leaving the cervical and middle dentin. The canal space was then enlarged with files, Gates-Glidden burs, and parapost drills. The teeth were ground on either the mesial or distal sides, permitting direct access to the entire canal. The cervical or middle third dentin was treated with Kerr Root Canal Sealer liquid, alternating between the middle and cervical thirds. Each tooth served as its own control. The adhesive resin was then luted directly to the prepared canal. Specimens, 1 x 1 x 8 mm, were prepared and mounted to a Vitrodyne testing machine enabling microtensile bond strengths to be measured. Data were analyzed using a two-way ANOVA and the least squares means test. The mean microtensile bond strengths for the cervical and middle third dentin treated with eugenol were 13.6 +/- 6.1 MPa (n = 33) and 14.8 +/- 3.9 MPa (n = 29), respectively. Without the eugenol, the mean bond strengths were 18.1 +/- 6.0 MPa (n = 31) and 17.3 +/- 4.6 MPa (n = 31) for the cervical and middle sections. The specimens treated with the eugenol liquid had significantly lower bond strengths than those without eugenol (p < 0.05) only in the cervical third. The region of the tooth tested had no effect on bond strength. That is, bond strength of the cervical third was not significantly different from bond strength on the middle third in either of the two groups (with or without eugenol) tested.

Analysis of Variance↗
PubMedDate not supplied

Evaluation of the sensitizing potential of eugenol and isoeugenol in mice and guinea pigs.

The sensitizing properties of the fragrances eugenol and isoeugenol have been investigated experimentally. The potential of these materials to induce sensitization of the respiratory tract was examined using the mouse IgE test, a novel but as yet unvalidated method for the predictive identification of chemical respiratory allergens. Comparisons were made with the activity of eugenol and isoeugenol in two predictive tests for contact sensitization potential: the murine local lymph node assay and the guinea pig maximization test. Both chemicals elicited positive responses in these tests, isoeugenol exhibiting a greater potential for contact sensitization than eugenol. Isoeugenol was negative at all concentrations examined in the mouse IgE test. In the same assay, exposure to eugenol was associated with a statistically significant increase in serum IgE concentrations when initial application concentrations of 2.5% were used. However, at higher test concentrations eugenol was negative in the mouse IgE test. It is concluded that neither eugenol nor isoeugenol have a significant potential to cause sensitization of the respiratory tract, a conclusion that is apparently consistent with the lack of evidence for occupational respiratory allergy associated with exposure to these chemicals. The evidence for isoeugenol lacking respiratory sensitization activity is particularly strong and it is proposed that this chemical may be of value as a negative control in the development and validation of new predictive test methods for the identification of chemical respiratory allergens.

Allergens↗
PubMed1986

Toxicity studies on clove cigarette smoke and constituents of clove: determination of the LD50 of eugenol by intratracheal instillation in rats and hamsters.

Eugenol, eugenol acetate, beta-caryophyllene, and alpha-humulene are constituents of clove and clove cigarette smoke. The toxicity of these compounds was evaluated by intratracheal instillation in male F-344 rats. Eugenol was most toxic in this assay. The LD50 of eugenol was 11 mg/kg in male F-344 rats and 17 mg/kg in male Syrian golden hamsters. Congestion of the lung with interstitial hemorrhages, acute emphysema, and acute pulmonary edema were among the macroscopic and histologic findings observed in the animals after intratracheal administration of eugenol. Similar effects were not observed with male Syrian golden hamsters exposed to clove cigarette smoke. The estimated daily intake of eugenol for those hamsters exposed to clove cigarette smoke was below 2 mg/kg.

Animals↗
PubMed2005

Phospho-ser 15-p53 translocates into mitochondria and interacts with Bcl-2 and Bcl-xL in eugenol-induced apoptosis.

Our previous studies demonstrated that antiallergic effects of herbs such as clove and Magnoliae Flos (MF) resulted from the induction of apoptosis in mast cells. We here examined whether the antiallergic activity was caused by eugenol (4-allyl-2-methoxyphenol) which was one of major ingredients in the essential oils or extracts of numerous plants including clove and Magnoliae Flos. RBL-2H3 cells were treated with eugenol, and DNA electrophoresis, Western blotting, immunocytochemistry, confocal microscopy and immunoprecipitation were conducted. Effect of eugenol was tested using a rat anaphylaxis model. RBL-2H3 cells treated with eugenol showed typical apoptotic manifestations and translocation of p53 into mitochondria. Antisense p53 partially prevented the induction of apoptosis. Noticeably, we observed that p53 translocated into mitochondria was phosphorylated on ser 15. Phospho-ser 15-p53 physically interacted with Bcl-2 and Bcl-xL in mitochondria and its translocation into mitochondria preceded cytochrome c release and mitochondrial membrane potential (MMP) reduction. We also depicted that the survival of animals even after administration of the fatal dose of compound 48/80 might result from the decreased number of mast cells by eugenol pretreatment. In conclusion, eugenol induces apoptosis in mast cells via translocation of phospho-ser 15-p53 into mitochondria.

Animals↗
PubMed1990

Effects of zinc oxide-eugenol on leucocyte number and lipoxygenase products in artificially inflamed rat dental pulp.

The number of leucocytes and level of endogenous LTC4 in the pulp tissue were measured by a histological method and radioimmunoassay, respectively. When the mandibular incisor pulp was irritated by drilling a hole in the dentine without using any coolant, the number of polymorphonuclear leucocytes and lymphocytes and the concentration of LTC4 increased to 3.2, 1.9 and 1.8 times their respective levels in normal pulp 6 h after the injury. The total leucocyte number in blood collected from these rats was also increased significantly. In contrast, when the cavities cut in dentine were filled with a zinc oxide-eugenol mixture (powder: liquid 100 mg/25 microliters), the increase in the number of cells was significantly curtailed, and the LTC4 level fell to 50% of that in normal pulp within 1 h after the filling. No decrease in the LTC4 level was observed after filling with a zinc oxide-water mixture, but the level decreased in response to an increase in eugenol content in the zinc oxide-eugenol placed in the cavity. Biosynthesis of [14C]-HETE and HPETE from [14C]-arachidonic acid was inhibited by the addition of 10 microM eugenol to the pulp homogenate. Thus eugenol released from zinc oxide-eugenol inhibited the biosynthesis of lipoxygenase products and the early chemotactic accumulation of leucocytes.

Animals↗
PubMed1990

Formation of glutathione conjugates during oxidation of eugenol by microsomal fractions of rat liver and lung.

Rat hepatic and pulmonary microsomes catalyzed the formation of at least three distinct glutathione conjugates with eugenol (4-allyl-2-methoxyphenol). These three conjugates were identical with the products obtained from the chemical reaction of synthetic eugenol quinone methide and glutathione. The microsomal reaction was dependent on NADPH and oxygen and was inhibited by cytochrome P450 inhibitors such as metyrapone, 2-diethylaminoethyl-2,2'-diphenylvalerate (SKF 525-A), alpha-naphthoflavone and piperonyl butoxide. The enzyme responsible for eugenol oxidation was inducible with 3-methylcholanthrene but not phenobarbital pretreatment. The rate of formation of conjugates was not affected by the presence of glutathione-depleted cytosol which contained active glutathione transferase, even at low glutathione concentrations, suggesting that conjugation occurs nonenzymatically with an electrophilic metabolite of eugenol. Covalent binding to microsomal protein was observed using [3H]eugenol. Cumene hydroperoxide catalyzed the formation of these same glutathione conjugates via the formation of a quinone methide-like intermediate which was detected by spectroscopic means. Our results suggest that eugenol is oxidized by cytochrome P450 to a reactive quinone methide intermediate which can then covalently modify protein or conjugate with glutathione.

Animals↗
PubMed1986

Suppressed mutagenicity of benzo[a]pyrene by the liver S9 fraction and microsomes from eugenol-treated rats.

The mutagenicity of benzo[a]pyrene (B[a]P) in the Ames test using liver S9 fraction prepared from rats pretreated with eugenol (4-allyl-2-methoxyphenol) was suppressed to a lower level than that obtained using liver S9 from untreated rats. There was a reverse correlation between the mutagenicity of B[a]P and the dose of eugenol administered to the animals. Similarly suppressed mutagenicity was observed when liver microsomes, instead of the S9 fraction, were used in the Ames test. The mutagenic activity of B[a]P and arylhydrocarbon hydroxylase (AHH) could not be inhibited by the direct addition of eugenol into the assay mixtures. In eugenol-treated microsomes, cytochrome P-450 content, AHH activity and total B[a]P hydroxylase activity were decreased to 81, 29 and 48% of the control values, respectively. The mutagenicity of B[a]P catalyzed by microsomes from rats fed ad libitum on a diet containing 5% eugenol in the Ames test was significantly decreased. AHH activity and total B[a]P hydroxylase activity were also decreased in these liver microsomes. These results indicate that the activation of B[a]P in rat liver by cytochrome P-450, which metabolizes B[a]P to ultimate mutagens or carcinogens, is reduced by the administration of eugenol.

Administration, Oral↗
PubMed1993

Effects of the naturally occurring alkenylbenzenes eugenol and trans-anethole on drug-metabolizing enzymes in the rat liver.

In order to study the effects of trans-anethole and eugenol on drug-metabolizing enzyme activities in vivo, male Wistar rats were treated by gavage with trans-anethole (125 or 250 mg/kg body weight) or eugenol (250, 500 or 1000 mg/kg body weight) daily for 10 days. In liver microsomes and cytosol various phase-I and phase-II biotransformation enzyme activities were determined. No effect on total cytochrome P-450 content in liver microsomes from rats treated with eugenol or trans-anethole was observed. Administration of 1000 mg eugenol/kg body weight, but not the lower doses, significantly increased cytochrome P-450-dependent 7-ethoxy-resorufin O-deethylation (EROD) and 7-pentoxyresorufin O-depentylation (PROD); administration of trans-anethole (125 or 250 mg/kg body weight) did not alter EROD and PROD activities. In rat liver cytosol, UDP-glucuronyl transferase (GT) activity towards the substrate 4-chlorophenol was significantly increased in all treated rats, and activity towards 4-hydroxybiphenyl as substrate was significantly increased in rats treated with 250 mg trans-anethole/kg or with 500 or 1000 mg eugenol/kg. DT-diaphorase (DTD) activity was only significantly enhanced in the liver cytosol of rats treated with trans-anethole at 250 mg/kg body weight. Enhancement of cytosolic glutathione S-transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene was found for all eugenol- and trans-anethole-treated rats. In addition, significantly increased levels of GST subunit 2 were measured by HPLC in the liver cytosol of rats treated with eugenol (500 or 1000 mg/kg body eight) or trans-anethole (250 mg/kg body weight). It is concluded that both eugenol and trans-anethole preferentially induced phase II biotransformation enzymes in rat liver in vivo.

Allylbenzene Derivatives↗
PubMed2004

Eugenol isolated from the essential oil of Eugenia caryophyllata induces a reactive oxygen species-mediated apoptosis in HL-60 human promyelocytic leukemia cells.

Eugenol is a major component of essential oil isolated from the Eugenia caryophyllata (Myrtaceae), which has been widely used as a herbal drug. In this study, we investigated the effects of eugenol on the cytotoxicity, induction of apoptosis, and the putative pathways of its actions in human promyelocytic leukemia cells (HL-60) under the standard laboratory illumination. Eugenol-treated HL-60 cells displayed features of apoptosis including DNA fragmentation and formation of DNA ladders in agarose gel electrophoresis. We observed that eugenol transduced the apoptotic signal via ROS generation, thereby inducing mitochondrial permeability transition (MPT), reducing anti-apoptotic protein bcl-2 level, inducing cytochrome c release to the cytosol, and subsequent apoptotic cell death. Taken together, the present study demonstrated that ROS plays a critical role in eugenol-induced apoptosis in HL-60, and this is the first report on the mechanism of the anticancer effect of eugenol.

Apoptosis↗
PubMed2004

Influence of the powder/liquid ratio on the properties of zinc oxide-eugenol-based root canal sealers.

OBJECTIVE: The purpose of this study was to investigate the effects of modifications of the powder/liquid ratio by endodontists on the physical properties recommended by ISO standards as well as on other clinically relevant properties of zinc oxide-eugenol-based root canal sealers. METHODS: The powder/liquid ratio of two zinc oxide-eugenol-based root canal sealers (Cortisomol and Pulp Canal Sealer EWT) was recorded by 10 endodontists. The materials, prepared according to the different consistencies, were tested according to ISO standards to evaluate their physical properties. Their sealing efficiency and the release of eugenol were also evaluated on 20 single rooted teeth. RESULTS: Some results varied according to the material. Nevertheless, for both cements, an increased powder/liquid ratio led to a decreased flow, an increased radiopacity and a decreased amount of eugenol released. The variations in the powder/liquid ratio did not influence the dimensional changes and the apical leakage of both cements. SIGNIFICANCE: Variations in the powder/liquid ratio of zinc oxide-eugenol-based root canal sealers have a limited influence on the properties of the sealers. The endodontists can prepare the zinc oxide-eugenol-based root canal sealers at their chosen consistency according to the filling technique they use.

Analysis of Variance↗
PubMed1997

Eugenol protects neuronal cells from excitotoxic and oxidative injury in primary cortical cultures.

We examined the neuroprotective efficacy of eugenol against N-methyl-D-aspartate (NMDA)-, oxygen-glucose deprivation-, and xanthine/xanthine oxidase-induced neurotoxicity in primary murine cortical cultures. Eugenol (100-300 microM) attenuated NMDA (300 microM)-induced acute neurotoxicity by 20-60%. At the same concentration range, eugenol also inhibited NMDA (300 microM)-induced elevation in neuronal 45Ca2+ uptake by 10-30%. In the oxygen-glucose deprivation (50 min) neurotoxicity, eugenol (100-300 microM) prevented acute neuronal swelling and reduced neuronal death by 45-60% in a concentration-dependent fashion. Oxidative neuronal injury induced by xanthine/xanthine oxidase was also significantly reduced (75-90%) by eugenol (100- 300 microM) addition. These results suggest that eugenol may play a protective role against ischemic injury by modulating both NMDA receptor and superoxide radical.

Animals↗