Eugenol Solution Research Articles

Primeiro registro da espécie exótica, plati Xiphophorus maculatus (Günther, 1866), na área de inundação urbana de um rio neotropical brasileiro

Abstract: Aim This work reports the first occurrence of the exotic species Xiphophorus maculatus (Günther, 1866) in the Sorocaba River Basin. The introduction of non-native fish species has become common and many species have been introduced mainly through sport fishing, aquaculture and aquarium keeping. In the case of the Poeciliidae, most of the introduced species that have been recorded come aquarium keeping. The environment where the specimens were captured had a large number of macrophytes due to anthropization and is located in a strictly urbanized area of the municipality. Methods The collection was done through a rectangular dip net, with measures of 70 cm x 60 cm and a mesh of 1 mm. The specimens were anesthetized in eugenol solution, fixed in 10% formalin solution and preserved in 70% alcohol. The specimens were later deposited in a scientific collection. Results The record includes two female specimens from an urban wetland on the Sorocaba River, São Paulo State, Brazil. Conclusions In the municipality of Sorocaba, 63 species of fish have already been identified, belonging to 7 orders and 19 families and 6 are exotic, such as the Xiphophorus maculatus. Urban floodplains are poorly studied environments, thus presenting great potential for the occurrence of species that have not yet been inventoried. The monitoring and inventory of exotic species must be carried out systematically so that mitigating measures can be proposed in relation to the control of these species, and this is one of the major causes of biodiversity loss. In addition, developing a program for returning unwanted fish to aquarium stores can be effective in preventing the introduction of new aquarium fish and displaying warnings informing of the negative ecological effects of releasing aquarium fish in all bags, fish plastics, and aquarium store websites.

Eugenol and carboxymethyl cellulose derived nanocoating with insect repellent and long-term antibacterial activity

Eugenol (EUG) is a natural compound with antibacterial and insect repellent activity. Its processing, utilization, and storage are limited due to its strong volatility, instability, and low solubility in water. In this study, an amphiphilic polymer-based nano-green coating (CMC-CYST-EUG) based on carboxymethyl cellulose (CMC) has been prepared, EUG was grafted into CMC by thiol-ene click reaction of Cysteamine hydrochloride (CYST) to reduce the volatility of EUG. When exposed to the same environment, the antibacterial duration of CMC-CYST-EUG increased by 7.8 times compared with pure EUG. Liquid holding capacity of CMC-CYST-EUG on pakchoi leaf surface increased by 81% compared with EUG solution. It shows that CMC-CYST-EUG has good adhesion to fruits and vegetables and can prevent the loss of EUG. Strawberry treated with CMC-CYST-EUG can be stored for 7 days. Within the concentration range of 0.5–0.25 mg/mL, the antifeedant rate of CMC-CYST-EUG to pests was significantly higher than that of EUG. Importantly, cytotoxicity tests show that CMC-CYST-EUG is considered safe at low concentrations. This synthetic material provides a strategy for the development and utilization of volatile active substances. • CMC-CYST-EUG is prepared from natural materials via click chemistry reaction. • Such amphiphilic nanocoating can improve the stability and adhesion of active substance. • Such system has a good repellent effect and long-term antibacterial properties.

Binary combinations of thymol, carvacrol and eugenol for Amblyomma sculptum control: Evaluation of in vitro synergism and effectiveness under semi-field conditions

This study aimed to investigate the in vitro acaricidal effect of thymol, carvacrol and eugenol (binary combinations) and their synergistic effect on unfed larvae and nymphs of Amblyomma sculptum, estimate the cost to prepare a formulation with these compounds, and evaluate the formulations under semi-field conditions against A. sculptum larvae. To evaluate the acaricidal effect of the compounds alone or their binary combinations (1:1 ratio) the larval packet test was performed using six concentrations (0.3125 to 10.0 mg/mL) for larvae and seven concentrations (2.5 to 20.0 mg/mL) for nymphs. The cost to produce 1 L of thymol, carvacrol and eugenol solutions, combined or alone, was estimated. In the semi-field test, formulations were sprayed on Panicum maximum plots experimentally infested with unfed A. sculptum larvae. In the in vitro tests with larvae, a synergistic effect (synergism and moderate synergism) was observed for thymol + eugenol at all concentrations tested, while thymol + carvacrol and eugenol + carvacrol showed a synergistic effect at the concentration of 5.0 mg/mL. In the in vitro tests with nymphs, thymol + eugenol, thymol + carvacrol and carvacrol + eugenol showed a synergistic effect (synergism and moderate synergism) at a concentration of 5.0 mg/mL and higher. Combining the compounds reduced the concentrations required to obtain mortality rate above 95%, resulting in lower costs. Under semi-field conditions, the treatments with thymol + eugenol and carvacrol + eugenol showed efficacies of 63.2% and 42.6%, respectively. We conclude that, depending on the concentrations, the binary combinations of thymol, carvacrol and eugenol have a synergistic acaricidal effect on unfed A. sculptum larvae and nymphs, and under semi-field conditions the associations between thymol + eugenol and carvacrol + eugenol were effective against A. sculptum larvae.

Development of eugenol-loaded submicron emulsion and its antiepileptic effect through regulating the oxidative stress.

The purpose of this study was to develop an injectable submicron emulsion of eugenol (Eug-SE) and to investigate its antagonism on epilepsy. The formulation was optimized using a complete randomized design, comprising 5% (w/v) eugenol, 5% (w/v) soybean oil, 1.2% (w/v) egg phosphatidylcholine, 0.3% (w/v) poloxamer 188, and 0.03% (w/v) sodium oleate. The prepared Eug-SE was comprehensively evaluated in terms of its pharmaceutical characteristics, physicochemical stability, injection safety, antioxidant activity in vitro, and anti-epileptic effect in vivo. The mean particle size of Eug-SE was 176.1±10.3nm, the ζ-potential was -40.2±1.8mV, and the drug content was (95.3±0.4) %. Moreover, the Eug-SE displayed excellent stability and improved safety compared to the eugenol solution. The Eug-SE (20μg/mL) produced a significant neuroprotective effect against H2O2-induced oxidative damage in PC12 cells, which was attributed to the decrease of cellular reactive oxygen species level and mitochondrial damage. Besides, the in vivo test indicated that Eug-SE exerted an anti-epileptic effect in the PTZ treated mice. These results suggested that Eug-SE was a suitable dosage form of eugenol for injection, and displayed great therapeutic potential for neurological disease in the future.

Effects of clove essential oil and eugenol on quality and browning control of fresh-cut lettuce

This study confirmed the inhibitory effects of clove essential oil (CEO) and eugenol (EUG) on the browning and relevant enzymes of fresh-cut lettuce, and examined associated mechanisms by inhibition kinetics and computational docking analysis. Fresh-cut lettuce was treated with 0.05% CEO and 0.05% EUG solutions, resulting in inhibition of the deterioration of texture quality and browning of the lettuce surface and interior. Compared with the controls, CEO and EUG significantly inhibited the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD, all p<0.05). EUG suppressed PAL, PPO, and POD in vitro in a dose-dependent manner, with IC50 values of 5.4±0.9, 29.5±3.5, and 61.9±6.7mM, respectively. The binding and inhibition effects of EUG on PAL, PPO, and POD, determined by inhibition kinetics and computational docking analysis, established EUG as a competitive inhibitor of these browning-relevant enzymes.

Electrospun/electrosprayed polyurethane biomembranes with ciprofloxacin and clove oil extract for urinary devices

Polyurethane–eugenol solutions in N,N-dimethyl formamide were electrospun/electrosprayed onto polyurethane–ciprofloxacin biomembranes to obtain drug delivery systems for urinary devices. Following electrospinning/electrospraying, particle-fiber morphology was evidenced by scanning electronic microscope analysis. Contact angle determinations along with surface free energy calculations, moisture diffusion test, and diffusion coefficient determinations were done for polyurethane–ciprofloxacin biomembranes. Determination of bioactive ciprofloxacin release kinetics evidences non-Fickian/anomalous/diffusion mechanism, coupling Fickian diffusion with the relaxation of the polymeric chains within the matrix network. A slight increase in n values for electrospun/electrosprayed coated samples evidenced a behavior closer to a case II transport mechanism with zero-order kinetics. The biological activity of the electrospun/electrosprayed polyurethane membrane samples tested against Staphylococcus aureus, Sarcina lutea, Bacillus cereus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa showed comparable antibacterial activity with standard ciprofloxacin.

Anthelmintic activity of eugenol in tambaquis with monogenean gill infection

Abstract This study evaluated the effects of eugenol on the control of monogenean infestation in tambaqui gills. Naturally infected fish were subjected to eugenol baths at different concentrations (0, 5, 10 and 15 mg L − 1 ). After being immersed in a eugenol bath for 15 min, the fish were transferred to eugenol-free water for 30 min to remove parasites and sample for gill removal and parasite count (3 replicates per treatment, with 5 fish each). Fish sampling for parasite count was repeated after one week. The procedures were repeated in two other experiments, except for the bath periods, which lasted 30 min and 60 min. The bath with 10 mg L − 1 eugenol solution for 60 min was the most efficient against monogeans, decreasing their count by 81%. In conclusion, eugenol is efficient for controlling monogenean gill infection in tambaquis. However, other studies under field conditions are needed to improve the use of this natural substance for disease control and prevention.

Storage Stability and Antibacterial Activity of Eugenol Nanoliposomes Prepared by an Ethanol Injection–Dynamic High-Pressure Microfluidization Method

Eugenol is a major phenolic component with diverse biological activities. However, it is difficult to formulate into an aqueous solution due to poor water solubility, and this limits its application. In the present study, eugenol nanoliposomes (EN) were prepared by combining the ethanol injection method with the dynamic high-pressure microfluidization method. Good physicochemical characterizations of EN were obtained. The successful encapsulation of eugenol in nanoliposomes was confirmed by Fourier transform infrared spectroscopy. A good storage stability of EN was confirmed by its low variation of average particle diameter and encapsulation efficiency after 8 weeks of storage. No oil drops were found in EN after 8 weeks of storage at 4°C and at room temperature, which suggested that the poor water solubility of eugenol was overcome by nanoliposome encapsulation. Compared with that of eugenol solution, a relatively good sustained release property was observed in EN. The antibacterial activity of EN against four common foodborne pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes) was evaluated in both Luria broth and milk medium.

Repellent activity of eugenol on larvae of Rhipicephalus microplus and Dermacentor nitens (Acari: Ixodidae)

The repellent activity of eugenol was evaluated on Rhipicephalus microplus and Dermacentor nitens larvae in a bioassay based on the vertical migration of these tick larvae during the host-seek phase. Solutions were used at concentrations of 10, 20, 30, 40, and 50 μl/ml and a control only with the solvent ethanol 50 GL. The larvae's reaction of climbing the rods of filter paper was observed each hour for 12 h and once more at 24 h. The repellence was calculated as a percentage through visual estimation, from the tendency of the larvae to climb the rods when the top part was impregnated with the eugenol solutions. For R. microplus larvae, the four highest concentrations produced repellence levels were greater than 80 % for up to 9 h. The repellence rates after 10 h for the concentration of 10 μl/ml was lower than 2 % (p > 0.05); and after 24 h, the values observed for the concentrations of 40 and 50 μl/ml were 77 and 80 % (p < 0.05). For the D. nitens larvae, the repellence was greater than 80 % for up to 5 h at the concentrations of 40 and 50 μl/ml; and after 9 h, the repellence fell for all treated groups were significantly different than the control were found only at the three highest concentrations. Therefore, eugenol has repellent activity on the larval stage of these two tick species, with the R. microplus larvae being more sensitive.

In vitro and in vivo application of active compounds with anti-yeast activity to improve the shelf life of ready-to-eat table grape

The anti-yeast effects of several compounds at different concentrations were screened in vitro against main table grape spoilage yeasts. The compounds showing the most significant anti-yeast activity were applied by dipping to table grape, to evaluate the sensory perception. In a subsequent final step, dipping treatments with potassium sorbate, eugenol, citrus extract and ethanol, were applied to ready-to-eat seedless table grape, packaged in air or under modified atmosphere packaging (MAP). The in vitro test highlights good effects of cinnamon bark oil and citrus extract, even at the lowest concentrations used in this work. From a sensory point of view, the preliminary panel test selected potassium sorbate, citrus extract, eugenol and ethanol as most suitable substances. The in vivo application of active compounds showed that dipping in eugenol solution and ethanol (20 and 50%) in combination with MAP increased shelf life of fruit if compared to the control sample (24.08, 28.47, 35.79 and 14.26days, respectively).

Enhancement in antifungal activity of eugenol in immunosuppressed rats through lipid nanocarriers

In the present study eugenol loaded solid lipid nanoparticles (SLN) was prepared and characterized for particle size, polydispersity index, zeta potential, encapsulation efficiency, in vitro release and in vivo antifungal activity. Effect of addition of liquid lipid (caprylic triglyceride) to solid lipid (stearic acid) on crystallinity of lipid matrix of SLN was determined by using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. Transmission electron microscopy (TEM) was carried out to determine the morphology of SLN. In vivo antifungal activity of eugenol loaded lipid nanoparticles was evaluated by using a model of oral candidiasis in immunosuppressed rats. Particle size results showed that d(90) of SLN(1) (single lipid matrix) and SLN(2) (binary lipid matrix) was 332±14.2 nm and 87.8±3.8 nm, respectively. Polydispersity index was found to be in the range of 0.27-0.4 which indicate moderate size distribution. Encapsulation efficiency of SLN(2) (98.52%) was found to be more than that of SLN(1) (91.80%) at same lipid concentration (2%, w/v). Increasing of the solid lipid concentration from 2% (w/v) to 4% (w/v) resulted in increase in encapsulation efficiency and the particle size. SLN(2) shows faster release of eugenol than that of SLN(1) due to smaller size and presence of liquid lipid which provide less barriers to the diffusion of drug from matrix. TEM study reveals the spherical shape of SLN. FT-IR, DSC and XRD results indicate less crystallinity of SLN(2) than that of SLN(1). In vivo studies show no significant difference in log cfu value of all the groups at 0 day. At 8th day, log cfu value of group treated with saline (control), standard antifungal agent, eugenol solution, SLN(1) and SLN(2) was found to be 3.89±.032, 2.69, 3.39±.088, 3.19±.028 and 3.08±0.124, respectively. The in vivo study results indicate improvement in the antifungal activity of eugenol when administrated in the form of SLN.

In vitro and in vitro activity of eugenol oil ( Eugenia caryophylata) against four important postharvest apple pathogens

The activity of eugenol oil was evaluated in vitro and in vivo against four apple pathogens namely Phlyctema vagabunda, Penicillium expansum, Botrytis cinerea and Monilinia fructigena. The minimum inhibitory concentration (MIC) of eugenol incorporated in malt extract agar medium was found to be 2 mg ml − 1 . Mycelial growth of the four test pathogens was completely inhibited when treated with 150 µl l − 1 of volatile eugenol whether at 4 or 20 °C. Conidia of P. vagabunda, P. expansum, M. fructigena and B. cinerea suspended for 2 min in eugenol solution at 2 mg ml − 1 heated to 50 °C germinated at rates of 19, 37, 38 and 39%, respectively. Three different eugenol formulations (Tween 80, ethoxylate and lecithin) were tested for their in vivo efficacy against the tested pathogens on apples. Ethoxylate– and Tween 80–eugenol formulations applied at room temperature were ineffective in reducing disease incidence. When heated to 50 °C, both formulations induced phytotoxicity on apple surface and caused cuticle damages as revealed by scanning electronic microscopic observations. A mixture of eugenol at 2 mg ml − 1 and soy lecithin at 50 mg ml − 1 suppressed the phytotoxic symptoms produced by eugenol on apples and reduced the disease incidence of P. expansum, P. vagabunda, B. cinerea and M. fructigena to less than 7, 6, 4 and 2% respectively after 6 months of storage at 2 °C. The application of heated lecithin-formulated eugenol could become a successful alternative to the traditional fungicides used in postharvest disease management of apple fruit.

Pharmacokinetics of eugenol in rainbow trout ( Oncorhynchus mykiss)

Clove oil, eugenol being its main constituent, has been used to anaesthetise fish for the last decade however no pharmacokinetic study of this drug has yet been realised in fish. The objective of the present study was to determine the pharmacokinetic parameters following immersion of rainbow trout ( Oncorhynchus mykiss) in a eugenol solution. A total of 30 fish ( n = 3 per time point) of similar length and weight were immersed in a solution of 75 mg/L of eugenol for 15 min. After thorough rinsing, individuals were placed in a recuperation tank in oxygenated conditioned water. Blood samples were collected at selected time points (at predose and at 0.25, 0.5, 1, 2, 4, 6, 8, 24 and 48 h) post-exposition. The samples were then submitted to mass spectrometry analysis using dansyl-chloride derivatisation. Pharmacokinetic results obtained are a C max of 10.53 μg/mL, a AUC 0− t 16.55 μg h/mL, AUC 0 − inf 17.04 μg h/mL and a half life of 12.14 h. These results indicate that eugenol is well absorbed and eliminated using a bath immersion at 4 °C. The long half life suggests that eugenol may accumulate in trout following repeated administration and further studies are required to evaluate its potential toxicity.

Phytotoxicity of clove oil and its primary constituent eugenol and the role of leaf epicuticular wax in the susceptibility to these essential oils

Herbicidal activities of clove oil and its primary constituent eugenol on broccoli, common lambsquarters, and redroot pigweed and the role of crystalline leaf epicuticular wax (LEW) in susceptibility and retention of these essential oils were studied. Clove oil (2.5%) and eugenol (1.5%) were applied to leaves of greenhouse-grown broccoli, common lambsquarters, and redroot pigweed seedlings and effects on seedling growth and leaf cell membrane integrity were studied. Compared with eugenol, clove oil caused greater inhibition of seedling growth in all species. Both eugenol and clove oil caused greater loss of membrane integrity and inhibition of seedling growth in redroot pigweed, which has no crystalline LEW, compared with common lambsquarters, which has a thick layer of crystalline LEW. In broccoli seedlings with LEW, clove oil caused greater inhibition of growth than eugenol. Both clove oil and eugenol caused greater electrolyte leakage from broccoli leaves without LEW than in the leaves with LEW. Removal of LEW increased electrolyte leakage, an indicator of cell membrane damage, by 97% in eugenol-treated and 26% in clove oil–treated broccoli leaves. Susceptibility of broccoli seedlings and possibly some weed species may, therefore, be affected by factors (e.g., genetic, environmental) that influence the amount of LEW. Although the presence of LEW greatly reduced the retention of the essential oil solutions, there was no significant difference between the retention of clove oil and eugenol solutions, indicating that differences in their phytotoxicity to broccoli leaves was not due to differential foliar retention.

Investigations of eugenol efficacy in treatment of mange in swine

The acaricide efficacy, tolerability and safety of the active ingredient of the etheric oil of cloves eugenol was investigated in the treatment of mange in swine, and the obtained results were compared with the results of acaricide efficacy of the synthetic acaricide permethrin, which has been in use for quite a some time. A single application of permethrin in the form of a 1% solution showed maximum efficacy of 62.5%, and after three applications of 75.0% in the treatment of sarcoptes in swine mange. A single application of eugenol in the form of a 10% solution had maximum efficacy of 75.0%, and applied three times an efficacy of 100% in curbing Sarcoptes scabiei var. suis. A single administration of 20% eugenol solution showed maximum efficacy of 87.5%, and applied three times it was 100% efficient in curbing Sarcoptes scabeiei var. suis. The best efficacy in the treatment of sarcoptes mange in swine was achieved with three applications of eugenol in a concentration of 20%. This maximum effect (100%) was obtained already after the second treatment. Eugenol in a concentration of 10% was safe for local application on skin because it does not cause any undesired reactions, while a 20% concentration caused irritation followed by a passing redness and disquiet in a smaller number of treated animals. The results of comparative investigations of acaricide efficacy of permethrin and eugenol demonstrate that there is resistence in Sarcoptes scabiei var. suis to permethrin. The biocide eugenol can safely be recommended for the treatment of sarcoptes mange in swine.

Stability and Antimicrobial Efficiency of Eugenol Encapsulated in Surfactant Micelles as Affected by Temperature and pH

Growth inhibition of four strains of Escherichia coli O157:H7 (H1730, F4546, 932, and E0019) and Listeria monocytogenes (Scott A, 101, 108, and 310) by eugenol encapsulated in water soluble micellar nonionic surfactant solutions (Surfynol 485W) adjusted to pH 5, 6, and 7 and incubated at 10, 22, and 32°C was determined. Concentrations of eugenol ranged from 0.2 to 0.9% at a surfactant concentration of 5%. Antimicrobial activity was assessed using a microbroth dilution assay. Eugenol encapsulated in surfactant micelles inhibited both microorganisms at pH 5, 6, and 7. At pH 5, some inhibition occurred in the absence of eugenol, i.e., by the surfactant itself (optical density at 24 h for L. monocytogenes = 0.07 and optical density at 24 h for E. coli O157:H7 = 0.09), but addition of >0.2% eugenol led to complete inhibition of both microorganisms. Inhibition of L. monocytogenes and E. coli O157:H7 decreased with increasing pH, that is, the minimum inhibitory concentration was 0.2, 0.5, and 0.5% of micellar encapsulated eugenol solutions at pH 5, 6, and 7, respectively. The encapsulated essential oil component in surfactant micelles was effective at all three temperatures tested (10, 22, and 32°C), indicating that the activity of encapsulated eugenol was not affected by high or low (refrigeration) temperatures. Overall, strains of E. coli O157:H7 were more sensitive than strains of L. monocytogenes. Improved activity was attributed to increased solubility of eugenol in the aqueous phase due to the presence of surfactants and improved interactions of antimicrobials with microorganisms.

Antimycotic Activity of Eugenol against Selected Water Molds

This study was conducted to investigate the antimycotic activities of eugenol, a major essential oil of clove, against some fish pathogenic species of Saprolegniaceae as well as to determine the toxicity of eugenol to selected cultured fish. Two eugenol solutions were used in this study, a 10% v/v (volume:volume) solution in dimethyl sulfoxide (DMSO) and FA 100, which contains 10% v/v eugenol. The fungal species investigated were Saprolegnia parasitica, S. diclina, S. ferax, S. salmonis, Achlya klebsiana, and Aphanomyces piscicida. The minimum inhibitory concentrations (MICs) of eugenol in DMSO against Saprolegnia spp., A. klebsiana, and A. piscicida were 500, 250, and 125 μg/mL, respectively, and the fungicidal concentrations (for complete killing) were 1,000, 500, and 250 μg/mL, respectively. In contrast, the MICs of FA 100 against S. parasitica, other Saprolegnia spp., A. klebsiana, and A. piscicida were 250, 125, 250, and 63 μg/mL, respectively, and the fungicidal concentrations were 1,000, 1,000, 1,000, and 63 μg/mL, respectively. Zoospores of the Saprolegnia spp. tested and of A. klebsiana could not germinate in the presence of a concentration of 250 μg/mL of either eugenol solution, while those of A. piscicida were killed by a concentration of 125 μg/mL of either eugenol solution. Eugenol was highly toxic to salmonids but less toxic to cyprinids.

Eugenol diffusion through dentin related to dentin hydraulic conductance

Objectives: The purpose of this study was (1) to find an easy way of evaluating the concentration of eugenol in cell culture fluids; (2) to confirm the relationship between the concentration and the cytotoxicity of eugenol in vitro; (3) to evaluate the cytotoxicity of four temporary eugenol-based filling materials: IRM, super EBA, Kalsogen and zinc oxide–eugenol cement; and (4) to establish a relationship between dentin permeability, eugenol diffusion and cytotoxicity. Methods: (1) The concentration of eugenol was measured with a spectrofluorimeter; (2) the cell viability of L 929 cells cultivated for 24 h with eugenol-containing medium was evaluated by the MTT assay; (3) after measurement of hydraulic conductance, occlusal cavities in human teeth in vitro were filled with the restorative materials. The cytotoxicity was measured with undiluted test medium and with various dilutions in culture medium; (4) after Lp measurement, the eugenol concentration in the media in the pulp chamber that diffused from IRM and 10 −3 mol/l eugenol solution was measured. Results: (1) A proportional relationship ( p=0.001 and r=1) was found between the concentration of eugenol; (2) eugenol started to be cytotoxic at 10 −5 mol/l and killed 95% of the cells at 10 −3 mol/l; (3) zinc oxide–eugenol cement was the most cytotoxic filling material when tested with the 1:100 dilution; (4) a significant relationship was found between Lp and cytotoxicity ( p=0.04) depending on the dilution of the test medium. A significant relationship was found between Lp and eugenol diffusion from a 10 −3 mol/l solution ( p=0.03) but not between Lp and eugenol diffusing from solid IRM (non significant). Significance: Eugenol diffusion from zinc oxide–eugenol cement appears to depend more on the role of hydrolysis of eugenol from zinc oxide–eugenol cement than on dentin permeability.

Relationship of Eugenolate Formation to the Setting Mechanism of Zinc Oxide Eugenol Cements

In Dentistry, a mixture of eugenol liquid (extract of oil of cloves) and zinc oxide powder enjoys many favored uses. The mixture is used as an obtunding temporary filling material, for temporarily cement­ ing dental inlays, crowns and bridges, for endodontic treatment and for taking impressions of edentulous cases. Despite this popularity of the material and its significance in dentistry, the hardening or setting mechanism of the material is not full y understood. Review of the literature 1 • 6 indicates that the major problem with respect to the setting of zinc oxide­ eugenol (ZOE) cement is whether zinc cugenolate crystals form as a result of the setting reaction and whether their formation causes the setting of the mix. The studies that dealt with the acceleration of ZOE 7 • 11 showed no systematic work to study the ef­ fect of an accelerator on the setting time of ZOE. The accelerator's efficiency was referred to its cation by some investigators 11 and to its anion3 by others. The purpose of this investigation was to study the effect of several accelerators when used in a powder form and as eugenol solutions on the setting time of ZOE; to study the relationship between the time of formation of eugenolate crystals and the setting time of ZOE; to illustrate whether the acceleration of ZOE is cationic or anionic in nature; and to study the effect of accelerator concentration 12 and eugenolate con­ centration on the compressive strength of ZOE.

The Application of Δε-Analysis to Pharmaceuticals: The Determination of Eugenol

The Δe-method of analysis, which was developed for the investigation of lignins, involves the selective modification of a given chromophore in a mixture of chromophores. This method permits the quantitative determination of a single ultraviolet-absorbing compound in mixtures of such absorbing materials. The analyses of eugenol in clove oil, in eugenyl acetate, and in two formulations are described as illustrations of the pharmaceutical application of this technique. The absorbance at 296 m μ of an aliquot of the eugenol-containing preparation was determined in basic solution. The change in absorbance was then compared to the bathochromic displacement of a standard eugenol solution with a corresponding change in pH.