Allergic reactivity for different dilutions of eugenol in repeated open application test and patch testing.

BACKGROUND: Eugenol is a known contact sensitiser included in fragrance mix I. OBJECTIVE: To assess the allergic reactivity to eugenol in different concentrations using patch test as well as repeated open application test (ROAT). METHODS: Overall 67 subjects from 6 European dermatology clinics participated in the study. The ROAT was performed for 21 days twice a day, applying 3 dilutions of eugenol (2.7%-0.5%) and a control. Before and after the ROAT, patch testing with 17 dilutions of eugenol (2.0%-0.00006%) and controls was performed. RESULTS: Out of the 34 subjects with contact allergy to eugenol, 21 (61.8%) showed a positive patch test before ROAT was performed, the lowest positive concentration was 0.031%. The ROAT was positive in 19 (55.9%) of the 34 subjects, the time until a positive reaction occurred was negatively associated with the concentration of the ROAT solution, as well as with the allergic reactivity of the subjects as defined by patch testing. In the patch test after ROAT, 20 of the 34 test subjects (58.8%) showed a positive reaction. In 13 (38.2%) of the 34 test subjects, the patch test result was not reproduceable, still 4 (31.0%) of these 13 subjects developed a positive ROAT. CONCLUSION: Eugenol can provoke a positive patch test reaction in a very low dose; besides, this hypersensitivity may persist even if a former positive patch test is not reproduceable.

The anticarcinogenic effect of eugenol on lung cancer induced by diethylnitrosamine/2-acetylaminofluorene in Wistar rats: insight on the mechanisms of action.

This study was designed to assess the ameliorative effects of eugenol and to propose the possible mechanisms of action of eugenol in diethylnitrosamine (DENA)/acetylaminofluorene (AAF)-caused lung cancer in Wistar rats. To induce lung cancer, DENA at a dose of 150 mg/kg body weight (b.wt) for 2 weeks were intraperitoneally injected once each week and AAF was administered orally at a dose of 20 mg/kg b.wt. four times each week for the next 3 weeks. DENA/AAF-administered rats were orally supplemented with eugenol at a dose of 20 mg/kg b.wt administered once a day until 17 weeks starting from the 1st week of DENA administration. Lung histological lesions, including sheets of tumor cells, micropapillary adenocarcinoma, and apoptotic cells, resulting from the DENA/AAF dosage, were ameliorated by eugenol treatment. However, a significant drop in the levels of LPO in the lungs and a remarkable rise in GSH content and GPx and SOD activities were observed in DENA/AAF-administered rats treated with eugenol compared with those in DENA/AAF-administered controls. Moreover, in DENA/AAF-administered rats, eugenol supplementation significantly reduced TNF-α and IL-1ß levels and mRNA expression levels of NF-κB, NF-κB p65, and MCP-1 but significantly elevated the level of Nrf2. Furthermore, the DENA/AAF-administered rats treated with eugenol exhibited a significant downregulation of Bcl-2 expression levels in addition to a significant upregulation in P53 and Bax expression levels. Otherwise, the administration of DENA/AAF elevated the protein expression level of Ki-67, and this elevation was reversed by eugenol treatment. In conclusion, eugenol has effective antioxidant, anti-inflammatory, proapoptotic, and antiproliferative properties against lung cancer.

Eugenol as a Potential Drug Candidate: A Review.

Eugenol is a bioactive compound widely available in many herbs like clove, cinnamon, tulsi, pepper etc. The compound is known for its antioxidant, antimicrobial, anesthetic, anti-inflammatory, neuroprotective, anti-diabetic, and anti-cancer activities. In pharmaceutical analysis, eugenol is used as a marker for single drugs and drug products. Dental care, household, and personal hygiene products are other areas where it has established its potential. In the food industry, eugenol is used as a flavouring agent in non-alcoholic beverages, baked foods, and chewing gums. Considering the huge potential of eugenol, this review is an attempt to collate the regulatory information, physico-chemical properties, toxicity profile, marketed conventional and novel formulations, analytical methods, extraction procedures, recent patents and clinical trials of the moiety. Based on literature survey a schematic diagram of mechanism of action has also been made.

The Potential Link between Episodes of Diverticulitis or Hemorrhoidal Proctitis and Diets with Selected Plant Foods: A Case-Control Study.

Diverticulitis and hemorrhoidal proctitis in the population are significant public health problems. We studied the potential association between the intake of certain plant foods and diverticulitis or hemorrhoidal episodes through a case-control study including 410 cases and 401 controls. We used a semiquantitative food frequency questionnaire. The intake was additionally quantified according to a 24 h recall. The plant foods or derived food products were categorized by their main chemical components into ethanol, caffeine/theine/theobromine, capsaicin, alliin, acids, eugenol, and miscellaneous foods such as curcumin. The mean score for overall intake of plant foods under consideration was 6.3 points, and this was significantly higher in cases (8.5) than in controls (4.1). Overall intake was similar in cases presenting with diverticulitis or hemorrhoidal proctitis. Cases had 13 times the odds of being in the upper quartile for overall intake (>7 points), compared to controls. Explanatory logistic regression models showed that the strongest association with diverticulitis and hemorrhoidal proctitis was shown by the chemical food group of capsaicin, followed by ethanol, eugenol, caffeine/theine/theobromine, and acids. Neither alliin nor miscellaneous food groups showed any association. High, frequent consumption of capsaicin, followed by ethanol, eugenol, caffeine/theine/theobromine, and acids increase the risk of diverticulitis and hemorrhoidal proctitis.

Relevant essential oil components: a minireview on increasing applications and potential toxicity.

Phenolic compounds carvacrol, thymol, eugenol, and vanillin are four of the most thoroughly investigated essential oil components given their relevant biological properties. These compounds are generally considered safe for consumption and have been used in a wide range of food and non-food applications. Significant biological properties, including antimicrobial, antioxidant, analgesic, anti-inflammatory, anti-mutagenic, or anti-carcinogenic activity, have been described for these components. They are versatile molecules with wide-ranging potential applications whose use may substantially increase in forthcoming years. However, some in vitro and in vivo studies, and several case reports, have indicated that carvacrol, thymol, and eugenol may have potential toxicological effects. Oxidative stress has been described as the main mechanism underlying their cytotoxic behavior, and mutagenic and genotoxic effects have been occasionally observed. In vivo studies show adverse effects after acute and prolonged carvacrol and thymol exposure in mice, rats, and rabbits, and eugenol has caused pulmonary and renal damage in exposed frogs. In humans, exposure to these three compounds may cause different adverse reactions, including skin irritation, inflammation, ulcer formation, dermatitis, or slow healing. Toxicological vanillin effects have been less reported, although reduced cell viability after exposure to high concentrations has been described. In this context, the possible risks deriving from increased exposure to these components for human health and the environment should be thoroughly revised.

Dual role of eugenol on chronic gastric ulcer in rats: Low-dose healing efficacy and the worsening gastric lesion in high doses.

This study evaluated the gastric healing activity of eugenol, the main bioactive compound from clove (Syzygium aromaticun) essential oil. Five groups of female Wistar rats were submitted to acetic acid-induced ulcer model and treated with Vehicle (1 mL/kg, p.o.), eugenol (1, 10 or 100 mg/kg, p.o) or omeprazole (20 mg/kg, p.o), twice a day, by seven or fourteen days. Macroscopic, microscopic and biochemical analyses were performed in the ulcerated site. Eugenol (1 mg/kg, p.o) administered by 7 or 14 days accelerated the gastric healing process by 33% and 52%, respectively. The healing actions of eugenol were accompanied by the rescue on the histological architecture and the normalization of the superoxide dismutase and catalase activity. Moreover, eugenol (1 mg/kg, p.o) reduced the gastric mucosal myeloperoxidase activity and increased the mucin secretion. In contrast, eugenol at a dose of 100 mg/kg administered by 7 days enhanced 49% the ulcerated area, but at 10 mg/kg did not change the ulcer area after 7 or 14 days of treatment. Thus, despite the undesirable results due to the worsening of the gastric lesion with the use of eugenol in high doses, the antiulcer potential of this compound is evident and manageable in an adequate dose.

A Comparison of Buffered Tricaine Methanesulfonate (MS-222) and Isoeugenol Anesthesia for Caudal Fin Clipping in Zebrafish (Danio rerio).

The purpose of this study was to compare the safety and efficacy of buffered tricaine methanesulfonate (MS-222) and isoeugenol for the anesthesia of zebrafish undergoing caudal fin clipping. Eighty 9 mo Danio rerio (AB strain) zebrafish were allocated to one of 2 equal groups: buffered MS-222 (168 mg/L, n = 40) or isoeugenol (20 mg/L, n = 40). The time to induction of anesthesia was significantly shorter in the isoeugenol group (141 ± 70 s) than in the MS-222 group (207 ± 103 s). The time to recovery from anesthesia was also shorter in the MS-222 group (373 ± 125 s) than in the isoeugenol group (491 ± 176 s). No obvious displays of distress or aversion to anesthesia were observed in either group. No difference was detected in the proportion of zebrafish that became anesthetized with either drug. One male zebrafish in the buffered MS-222 group was found dead at the 1-h post-procedural monitoring time point, but there was no difference between groups in the proportion of fish that survived anesthesia to the end of experiment. In conclusion, the safety and efficacy of buffered MS-222 (168 mg/L) and isoeugenol (20 mg/L) was similar for zebrafish undergoing anesthesia for caudal fin clipping.

Acute Administration of Methyleugenol Impairs Hippocampus-Dependent Contextual Fear Memory and Increases Anxiety-like Behavior in Mice.

Methyleugenol (ME) as a natural essential oil in many plant species is widely used in human food and beverage for its fragrance and possible beneficial health effects. Previous chronic or subacute studies in rodents show that ME mainly causes liver toxicity. However, whether and how acute ME affects the central nervous system still remain elusive. Here, we found that ME administrated into the hippocampus impaired the acquisition of hippocampus-dependent contextual fear memory in mice (ME vs control: repeated-measures two-way ANOVA, F(5,70) = 2.937, p < 0.05; Fisher test, p < 0.05, respectively, 53 ± 5.2% vs 73 ± 7.6% during trial 4 and 46.8 ± 6% vs 74.5 ± 9.3% during trial 5). Meanwhile, acute ME impaired hippocampal CA1 long-term potentiation (LTP; ME vs control: independent t-test, p < 0.01, 110.6 ± 1.8% vs 133.3 ± 5.6%) while facilitated long-term depression (LTD; p < 0.01, 75.7 ± 3.4% vs 88.6 ± 1.7%) in mice brain slices and inducing a decrease in learning-dependent phosphorylation of Ser831 (ME vs control: independent t-test, p < 0.001, 0.87 ± 0.03 vs 1.23 ± 0.03) and Ser845 (p < 0.01, 0.42 ± 0.07 vs 0.97 ± 0.14) sites of excitatory glutamate AMPA receptor subunit 1 (GluA1) in the hippocampus, which may be the underlying mechanisms of impairment of hippocampus-dependent learning. In addition, intrahippocampal infusion of ME also increased anxiety-like behaviors in mice. These results suggested that acute ME impaired the hippocampus function at behavioral, cellular, and molecular levels, indicating the potential risks of ME on the central nervous system.

Is Isoeugenol a Prehapten? Characterization of a Thiol-Reactive Oxidative Byproduct of Isoeugenol and Potential Implications for Skin Sensitization.

Isoeugenol is widely used by the cosmetic and fragrance industries, but it also represents a known cause of skin sensitization adverse effects. Although devoid of a structural alert, isoeugenol has been classified as prehapten in virtue of the presence of a pre-Michael acceptor domain. Isoeugenol oxidation could theoretically lead to the generation of reactive toxic quinones, and photoinduced oxidative degradation of isoeugenol was reported to generate strongly thiol reactive byproducts. Nonetheless, the isoeugenol degradation product responsible for increased reactivity was found to be elusive. In the present study, an aged isoeugenol sample was subjected to reactivity-guided experiments to trap elusive thiol reactive species with a fluorescent nucleophile, viz. dansyl cysteamine (DCYA). The results herein presented demonstrate that photo-oxidation of isoeugenol led to the formation of a dimeric 7,4'-oxyneolignan with strong chemical reactivity, capable of nucleophilic substitution with thiols. The results were confirmed by isolation, structural characterization, and further NMR reactivity studies. Isoeugenol is already well-known as moderately reactive in thiol depletion assays, and was herein demonstrated to be capable of converting to more potent electrophilic species upon degradation, thus acting as a prehapten. The application of the reactivity-guided strategy described herein was shown to serve as an effective tool to investigate elusive skin sensitizers.

Fragrances: Contact Allergy and Other Adverse Effects.

This article gives an overview of fragrance allergy. The following subjects are discussed: composition of perfumes, contact with fragrances, diagnosing fragrance allergy, frequency of allergy, clinical picture of allergic contact dermatitis, culprit products, occupational contact dermatitis, and other adverse effects of fragrances. For diagnosing fragrance sensitization, personal products and a fragrance series may need to be tested in addition to the baseline series. In the general adult population, up to 4.5% may be allergic to fragrance materials, and in consecutive patients patch tested for suspected contact dermatitis, the frequency may reach 20% to 25%. More than 150 fragrances have caused contact allergy. The most frequent sensitizers are linalool and limonene hydroperoxides, hydroxyisohexyl 3-cyclohexene carboxaldehyde, treemoss and oakmoss absolute, isoeugenol, cinnamyl alcohol, and cinnamal. Culprit products for induction of sensitization are often deodorants, fine fragrances, and aftershaves. Occupational contact dermatitis from fragrances is seen occasionally. Other adverse effects are all discussed but occur infrequently.

Be Aware of a Potential Pitfall in Oral and Dental Specimens: Alvogyl Fibers.

Alvogyl dressing is used to help control hemostasis, foster healing, and prevent complications after certain oral procedures. It is a paste composed of different antiseptic and analgesic substances, and fern-derived Penghawar djambi fibers that have styptic properties. It is claimed to be a resorbable and self-eliminating paste with little complications. However, some studies have demonstrated detrimental effects. We report 3 cases of postextraction nonhealing sockets after Alvogyl dressing. Histologically, they demonstrated residual Alvogyl fibers with foreign body giant cell stromal reaction and complications that were clinically confused with abscess, cysts, infections, and neoplastic lesions. Being unaware of their histopathologic appearances, the foreign bodies in 2 cases were initially confused with fungal hyphae, parasitic ova, vegetable material, and other surgical and nonsurgical materials. To add to our confusion, they were periodic acid-Schiff (PAS) and Grocott methenamine silver (GMS) positive, septated, spiked, and calcified. A history of Alvogyl dressing was retrospectively found. Learning from our mistakes and being aware of the histologic manifestations of Alvogyl fibers, the third case was correctly spotted. Because Alvogyl fibers are undissolvable and are not spontaneously eliminated, they may, if left for a long period, elicit tumefactive foreign body giant cell stromal and epithelial reactions that can be confused with inflammatory, infectious, and neoplastic lesions. Histologically, they can mimic infectious agents and noninfectious materials. Because history of dressing is not always provided, pathologists should be familiar with their histomorphologic features to avoid pitfalls and guide clinicians to correct diagnosis and management. In absence of history, certain histologic features are helpful hints.

Sensitization to fragrances in Spain: A 5-year multicentre study (2011-2015).

BACKGROUND: Fragrance chemicals constitute the second most frequent cause of contact allergy in Spain. There are no data available concerning the individual fragrances that are most frequently involved. OBJECTIVES: To describe the diagnostic contribution provided by specific fragrance series to the results obtained with baseline series fragrance markers by correlating the results of both series. MATERIALS AND METHODS: We performed a 5-year retrospective study of fragrance marker-positive patients tested with specific fragrance series in 23 Spanish centres. We collected the demographic and clinical characteristics, and compared the results of patch tests obtained from different suppliers. RESULTS: Of 19 588 patients patch tested with the Spanish baseline series, 1590 (8.1%) reacted positively to a fragrance marker. Of these, 1013 (63.7%) were patch tested with a fragrance series, and 664 patients reacted positively to at least one individual fragrance other than hydroxyisohexyl 3-cyclohexene carboxaldehyde. Geraniol was the most frequent allergen. Positive reactions to substances not included in fragrance mix (FM) I or FM II were found in 230 patients. Of the 436 FM I-positive patients and the 419 FM II-positive patients, 184 (42%) and 64 (39.1%), respectively, had no positive reactions to fragrance series. In the case of FM I, negative results were more common when individual fragrances were patch tested at low concentrations. CONCLUSIONS: We recommend patch testing all patients positive for any fragrance marker with a specific fragrance series. The correlation between the results of baseline series and fragrance series could be improved by increasing the concentrations of individual fragrances.

Antinociceptive local activity of 4-allyl-1-hydroxy-2-methoxybenzene (eugenol) by the formalin test: an anti-inflammatory effect

Eugenol has been employed for decades as a condiment, an antimycotic, an antibacterial, an antiviral, and an antioxidant, and it is one of the natural analgesics most frequently utilized for pain and inflammation. Our objective was to determine the analgesic/anti-inflammatory effect of eugenol compared with diclofenac, naproxen, and tramadol using the formalin test. The formalin method was used in 6- to 10-week-old Wistar rats (weighing 250 g each) divided into six groups: saline (0.9%); formalin (5%); diclofenac (250 µg/kg); naproxen (400 µg/kg); tramadol (500 µg/kg), and eugenol (1,400 µg/kg), in the intraplantar part of the hind-end trunk of the rats, with n = 5 per group. Eugenol diminished 44.4% of nociceptive behavior in phase 1 and 48% in phase 2 (p ≤0.05 vs formalin). Eugenol was shown to be 1.14 times more effective than diclofenac, but 1.62 and 1.75 times less effective than naproxen and tramadol, respectively, in phase 1 and 1.45 times less effective than diclofenac and naproxen and 1.66 less effective than tramadol in phase 2 (p ≤0.05). These data suggest that eugenol possesses moderate activity in the acute pain phase and greater activity in inflammatory-type pain, and both effects are comparable to those produced by diclofenac and are less than the effects produced by naproxen and tramadol in the formalin test

Impact of dental cement on the peri-implant biofilm-microbial comparison of two different cements in an in vivo observational study.

BACKGROUND: The type of cement used in cemented fixed implant-supported restorations influences formation of undetected excess cement and composition of the peri-implant biofilm. Excess cement and dysbiosis of the biofilm involve the risk of peri-implant inflammation. PURPOSE: The aim of the study was to investigate the impact of two different cements on the peri-implant biofilm and inflammation. MATERIALS AND METHODS: In an observational study, the suprastructures of 34 patients with cemented fixed implant-supported restorations were revised. In 20 patients, a methacrylate cement (Premier Implant cement [PIC]) and in 14 patients, a zinc oxide eugenol cement (Temp Bond [TB]) were used. After revision, TB was used for recementation. During revision and follow-up after 1 year, microbial samples were obtained. RESULTS: Excess cement was found in 12 (60%) of the 20 patients with PIC. Suppuration was observed in two (25%) implants with PIC without excess cement (PIC-) and in all 12 (100%) implants with PIC and excess cement (PIC+). Implants cemented with TB had neither excess cement nor suppuration. The taxonomic analysis of the microbial samples revealed an accumulation of periodontal pathogens in the PIC patients independent of the presence of excess cement. Significantly, fewer oral pathogens occurred in patients with TB compared to patients with PIC. TB was used in all cases (PIC and TB) for recementation. In the follow-up check, suppuration was not found around any of the implants with PIC-, only around one implant with PIC+ and around one implant with TB. Bacterial species associated with severe periodontal infections that were abundant in PIC- and PIC+ samples before the revision were reduced after 1 year to levels found in the TB samples. CONCLUSIONS: The revision and recementation with TB had a positive effect on the peri-implant biofilm in cases with PIC. The cementation of suprastructures on implants with TB is an alternative method to be considered.

Efficacy of Benzocaine, Eugenol, and Menthol as Anesthetics for Freshwater Angelfish.

For the production and commercialization of ornamental fish species, it is indispensable to collect biometric data that facilitate the selection of animals for trade and genetic improvement of the stock. However, during the handling process, fish receive more stress if proper anesthetics are not used. Thus, application of appropriate anesthetics is an important tool for minimizing stress in animals. The objective of this study was to determine the effective concentrations of benzocaine, eugenol, and menthol for achieving anesthesia in Freshwater Angelfish Pterophyllum scalare and to develop induction and recovery response curves for different concentrations of these anesthetics. In total, 75 fish were exposed to five concentrations of the three anesthetics in a completely randomized design: benzocaine at 60, 85, 110, 135, and 160 mg/L; eugenol at 40, 80, 120, 160, and 200 mg/L; and menthol at 50, 75, 150, 200, and 250 mg/L. Each concentration (5 fish/concentration) consisted of five replicates, with each replicate represented by a single fish. The results indicated that the tested substances met the criteria of anesthetic efficiency. The effective concentrations of benzocaine, eugenol, and menthol for the anesthesia of Freshwater Angelfish were identified as 89.25, 90.6, and 92.1 mg/L, respectively.

Effect of repeated exposure to AQUI-S® on the viability and growth of Neoparamoeba perurans.

There have been recent efforts amongst immunologists to develop approaches for following individual fish during challenges with viral and bacterial pathogens. This study contributes to assessing the feasibility of using such approaches to study amoebic gill disease (AGD). Neoparamoeba perurans, agent of AGD, has been responsible for widespread economic and fish loss in salmonid aquaculture. With the emergence of AGD in Europe, research into infection dynamics and host response has increased. This study investigated the effect of repeat exposure to anaesthesia, a necessary requirement when following disease progression in individual fish, on N. perurans. In vitro cultures of N. perurans were exposed every 4 days over a 28-day period to AQUI-S® (isoeugenol), a popular anaesthetic choice for AGD challenges, at a concentration and duration required to sedate post-smolt salmonids. Population growth was measured by sequential counts of amoeba over the period, while viability of non-attached amoeba in the culture was assessed with a vital stain. AQUI-S® was found to be a suitable choice for in vivo ectoparasitic challenges with N. perurans during which repetitive anaesthesia is required for analysis of disease progression.