Effect Of Essential Oil Research Articles

Spray-drying-microencapsulated Minthostachys verticillata essential oil and limonene as innovative adjuvant strategy to bovine mastitis vaccines

Design of innovative adjuvant strategies with an appropriate safety profile is relevant to developed subunit or inactivated microorganism vaccines for bovine mastitis. Minthostachys verticillata essential oil (EO) has demonstrated ability to stimulate the innate immune response and adjuvant effect similar to Al(OH)3. Here we evaluated the adjuvant effect of EO and its metabolite, limonene (L) alone and microencapsulated by spray-drying, using an inactivated Enterococcus faecium strain bovine-mastitis inducer. The gas chromatography–mass spectrometry analysis showed that microencapsulation process did not alter the EO or L chemistry. Microencapsulated EO (McEO) or L (McL) (2.0, 2.5 and 5.0 mg/ml) decreased the viability of bovine mammary gland epithelial cells in a dose-dependent way. Balb/c mice (n = 32) were subcutaneously inoculated (day 0) and revaccinated (day 14 and 28) with saline solution, inactivated bacteria alone or combined with Incomplete Freund's Adjuvant; EO or L (2.5 mg/ml); McEO or McL (5.0 mg/ml); or microcapsule wall material (Mc) alone (2.5 mg/ml). EO, L, McEO and McL stimulated E. faecium-specific IgG (IgG1 or IgG2a) with opsonizing capacity and increased the proportion of CD4+ and CD8+ T cells producers of IFN-γ. Microencapsulation was an effective strategy to increase the adjuvant potential of EO or L. These new adjuvants deserve further study to evaluate their incorporation into vaccines for bovine mastitis.

Essential Oils and Their Formulations for the Control of Curculionidae Pests

Pesticides are widely used in producing food to control pests. However, it has been determined that synthetic pesticides present severe toxicity (residual), while they also result in environmental contamination and development of high-level resistance in some insect species. Due to this, some of these susbtances have been banned or restricted in many countries, which has reduced the number of agrochemicals that can be used for pest control, particularly in the case of crops exported to green markets such as Europe and Asia. Under this scenario, essential oils (EOs) are being increasingly studied as bioinsecticides because they are renewable, natural, biodegradable, non-persistent in the environment and safe to non-target organism and humans. It has been determined that EOs have repellent, ovicidal, larvicidal, and insecticidal effects against different types of pests, but they also have some drawbacks due to their high volatility and low aqueous solubility. This mini-review focusses on EOs used as bioinsecticides for the control of Curculionidae and on current stabilization techniques, such as nanoencapsulation, to prolog the biocidal effect of EOs against these pests.

Attraction or Repelling Effects of Commercial Plant Essential Oils on the Synanthropic Cheiracanthium mildei (Araneae: Cheiracanthiidae).

The northern yellow sac spider Cheiracanthium mildei L. Koch, is expanding its range to Central Europe, especially to synanthropic habitats. The spiders become unwanted companions because of the unreasonable fear - arachnophobia, and estetic reason - silk retreats in corners, capturing dust. The most commonly used substances against spiders are pesticides, which are, however, toxic. In our work we tested the attraction or repellence of 15 essential oils (EO) from plants representing eight families to C. mildei. Our research has shown a significant repellent effect of EO from three plants, namely Syzygium aromaticum (L.) Merr. et L. M. Perry (Myrtales: Myrtaceae), Ananas comosus (L.) Merr. (Poales: Bromeliaceae) and Musa sp. (L.) (Zingiberales: Musaceae). In contrast, some EOs appeared to have an attraction effect, particularly Carum carvi L. (Apiales: Apiaceae). Zingiber officinale Roscoe (Zingiberales: Zingiberaceae) reduced the tendency of spiders to construct the silken retreat. S. aromaticum, A. sativus, Musa sp. and Z. officinale have the potential to be used as natural repellents against spiders.

The Use of Cinnamon Essential Oils in Aquaculture: Antibacterial, Anesthetic, Growth-Promoting, and Antioxidant Effects

Cinnamon essential oils (EOs) are widely known for their pharmaceutical properties; however, studies investigating the use of these EOs in aquaculture are scarce. The aims of this study were to evaluate the anesthetic effect of bathing silver catfish (Rhamdia quelen) with Cinnamomum cassia EO (CCEO) and its nanoemulsion (NCCEO); the growth-promoting and antioxidant effects of dietary supplementation with CCEO in silver catfish; and the in vitro antibacterial effect of CCEO, NCCEO, and Cinnamomum zeylanicum EO (CZEO) against bacteria isolated from diseased silver catfish. The two cinnamon EOs showed promising antibacterial activity, which was potentiated by the nanoemulsion. CCEO showed satisfactory anesthetic activity in silver catfish, and its nanoemulsion intensified the sedative activity. Supplementation of 1.0 mL CCEO per kg of diet for 60 days increased weight, length, and weight gain when compared to the control group, evidencing the growth-promoting activity of this EO. Dietary supplementation of CCEO for 30 and 60 days also showed an antioxidant effect, as it decreased levels of thiobarbituric acid reactive species and increased the superoxide dismutase activity in the liver of silver catfish. Therefore, cinnamon EOs have a promising use in aquaculture.

Eugenol and Pulegone as potential biorational alternatives for Trioza erytreae (Hemiptera: Triozidae) control: Preliminary results on nymphal toxicity and applicability on Citrus limon

Agricultural activity relays deeply on the usage of synthetic insecticides for pest control, however, the extensive use or misuse of these substances can have negative impacts on the environment, human health and even on agricultural ecological subsystems. Essential oils (EOs) are secondary metabolites synthesized in plant secretory structures that are less hazardous to the environment and safer to handle, with known effectivity against arthropods, thus presenting a viable eco-friendly alternative for typical synthetic insecticides. Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) is a major threat for citrus production, expanding rapidly throughout the Iberian Peninsula. To this day, no effective control method to sustainably control T. erytreae populations has thus far been obtained and the effects of EOs on this pest have not yet been documented. In this study, the insecticidal potential of EOs active compounds Eugenol (99 %), Pulegone (85 %) and their combination was assessed by determining their toxicity through topical application on T. erytreae nymphs and their phytotoxicity on Citrus limon ((L.) Burm.), T. erytreae preferred host, in laboratory conditions. Pulegone was more toxic to T. erytreae nymphs than Eugenol, showing the lowest LD50 values both after 24 h (0.005 µL nymph−1) and 48 h (0.003 µL nymph−1) whereas for the LD90, the combination of both oils was the most toxic both after 24 h (0.020 µL nymph−1) and 48 h (0.012 µL nymph−1). On concentrations equal or lower than 3.60 %, Eugenol presented the highest phytotoxic effect. In concentrations that did not pose a significant phytotoxic effect on C. limon, the combination of both active compounds exhibited the highest nymphal mortality. The beneficial integration of both Eugenol and Pulegone in a mixture was shown to be the best approach for utilizing these compounds, but care in their concentrations must be taken, given the possible effects on phytotoxicity. This preliminary study presents new insights on the potential effects of EOs on T. erytreae and their applicability in citrus crops, thus making an entry way for the development of more sustainable control strategies for this pest control.

The Antifungal Activity of Cinnamon-Litsea Combined Essential Oil against Dominant Fungal Strains of Moldy Peanut Kernels.

The antifungal activity of cinnamon (Cinnamomum cassia Presl), litsea [Litsea cubeba (Lour.) Pers.], clove (Syzygium aromaticum L.), thyme (Thymus mongolicus Ronn.) and citronella (Cymbopogon winterianus Jowitt) essential oils (EOs) against the dominant fungi isolated from moldy peanuts was investigated in this research. Firstly, strain YQM was isolated and identified by morphological characterization and 18S rRNA gene sequence analysis to be Aspergillus flavus (A. flavus). Next, antifungal effects of single or mixed EOs on strain YQM were evaluated by the inhibition zone test. The cinnamon-litsea combined essential oil (CLCEO, Vcinnamon oil:Vlitsea oil = 3:5) displayed the best antifungal effect on strain YQM. The chemical composition of CLCEO was identified and quantified by gas chromatograph-mass spectrometry (GC-MS), and results revealed that the major components of CLCEO were cinnamaldehyde and citral. Finally, the effect of EOs on the microstructure of strain YQM mycelia was observed under scanning electron microscope (SEM). The mycelia exposed to cinnamon essential oil (CEO) and litsea essential oil (LEO) were partly deformed and collapsed, while the mycelia treated with CLCEO were seriously damaged and the deformation phenomena such as shrinking, shriveling and sinking occurred. Therefore, CLCEO has great potential for using as anti-mildew agents during peanut storage.

A Meta-Analysis of Essential Oils Use for Beef Cattle Feed: Rumen Fermentation, Blood Metabolites, Meat Quality, Performance and, Environmental and Economic Impact

The objective of this study was to see how dietary supplementation with essential oils (EOs) affected rumen fermentation, blood metabolites, growth performance and meat quality of beef cattle through a meta-analysis. In addition, a simulation analysis was conducted to evaluate the effects of EOs on the economic and environmental impact of beef production. Data were extracted from 34 peer-reviewed studies and analyzed using random-effects statistical models to assess the weighted mean difference (WMD) between control and EOs treatments. Dietary supplementation of EOs increased (p < 0.01) dry matter intake (WMD = 0.209 kg/d), final body weight (WMD = 12.843 kg), daily weight gain (WMD = 0.087 kg/d), feed efficiency (WMD = 0.004 kg/kg), hot carcass weight (WMD = 5.45 kg), and Longissimus dorsi muscle area (WMD = 3.48 cm2). Lower (p < 0.05) ruminal concentration of ammonia nitrogen (WMD = −1.18 mg/dL), acetate (WMD = −4.37 mol/100 mol) and total protozoa (WMD = −2.17 × 105/mL), and higher concentration of propionate (WMD = 0.878 mol/100 mol, p < 0.001) were observed in response to EOs supplementation. Serum urea concentration (WMD = −1.35 mg/dL, p = 0.026) and haptoglobin (WMD = −39.67 μg/mL, p = 0.031) were lower in cattle supplemented with EOs. In meat, EOs supplementation reduced (p < 0.001) cooking loss (WMD = −61.765 g/kg), shear force (WMD = −0.211 kgf/cm2), and malondialdehyde content (WMD = −0.040 mg/kg), but did not affect pH, color (L* a* and b*), or chemical composition (p > 0.05). Simulation analysis showed that EOs increased economic income by 1.44% and reduced the environmental footprint by 0.83%. In conclusion, dietary supplementation of EOs improves productive performance and rumen fermentation, while increasing the economic profitability and reducing the environmental impact of beef cattle. In addition, supplementation with EOs improves beef tenderness and oxidative stability.

Impact of Silver Nanoparticles on Lemon Growth Performance: Insecticidal and Antifungal Activities of Essential Oils From Peels and Leaves.

Ten-year-old lemon (Citrus limon L. cv. Eureka) was used during the 2019 and 2020 seasons to investigate the effect of AgNPs at control, 5, 7.5, and 10 mg/L as a foliar application on vegetative growth, yield, and fruit quality. The selected trees were subjected to agricultural practices applied in the field during the study. The results indicated that the foliar application of AgNPs positively improved the shoot length, total chlorophyll, flower, and fruit set percentage, fruit yield, physical and chemical characteristics of fruits, and leaf mineral composition from macro and micronutrients compared to control in both seasons. The foliar application of AgNPs at 10 mg/L showed the highest mean values followed by 7.5 and 5 mg/L, respectively, for the previous characteristics. The treated leaves and fruit peels were hydrodistillated to extract the essential oils (EOs), and GC–MS analysis of leaf EOs. The analysis of leaves EOs showed the presence of neral, geranial, neryl acetate, and limonene as the main abundant bioactive compounds. While in peel the main compounds were neral, geranial, neryl acetate, D-limonene, geraniol acetate, linalool, and citronellal. Toxin effect of both EOs from leaves and peels were evaluated on the rice weevils (Sitophilus oryzae) and the results indicated a higher effect of lemon peel EOs than leaves based on mortality percentage and the values of LC50 and LC95 mg/L. Melia azedarach wood samples loaded with the produced lemon EOs were evaluated for their antifungal activity against the molecularly identified fungus, Fusarium solani (acc # OL410542). The reduction in mycelial growth was increased gradually with the applied treatments. The most potent activity was found in lemon leaf EOs, while peel EOs showed the lowest reduction values. The mycelial growth reduction percentages reached 72.96 and 52.59%, by 0.1% leaf and peel EOs, respectively, compared with control.

Chemical composition and anti-inflammatory activity of essential oils from resin of Commiphora species

ABSTRACT. Essential oils (EOs) were prepared by the hydro-distillation technique from the resins of four Commiphora species and analyzed by GC-MS. Major constituents of EOs were a-copaene (22.71%), β-caryophyllene (28.03%) and β-caryophyllene oxide (13.89%) for C. sphaerocarpa; a-pinene (29.1%) for C. africana; hexadecane (14.1%) for C. habessinica and δ-cadinene (31.5%) for C. schimperi. We investigated the anti-inflammatory effects of EOs in lipopolysaccharide (LPS) stimulated RAW 264.7 macrophages by measuring nitric oxide (NO). The effect in mRNA or protein level after EO treatment were evaluated by RT-PCR and Western blot analysis, respectively. Among four Commiphora species, C. sphaerocarpa EO demonstrated a significant inhibition of LPS by 27.2±3.6% at 10 μg/mL and 62.3±5.2% at 20 μg/mL. C. sphaerocarpa EO inhibited LPS mediated iNOS over expression in both protein and mRNA level with dose dependent manner. It inhibited phosphorylation of ERK1/2, p38, ATF2. The enhanced anti-inflammatory activity of the EO of the plant was due to HO-1 expression by ROS dependent Nrf2 activation in RAW264.7 cells. These findings indicate C. sphaerocarpa EO inhibits the pro-inflammatory responses by inhibiting MAPK/ATF2, and triggering ROS/Nrf2/HO-1 signaling. Therefore, C. sphaerocarpa EO could have potential for useful therapeutic candidate preventing and treating inflammatory diseases.
 
 KEY WORDS: GC-MS, Anti-inflammatory, C. africana, C. habessinica, C. sphaerocarpa, C. schimperi
 
 Bull. Chem. Soc. Ethiop. 2022, 36(2), 399-415. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i2.13

Characterization of active and pH-sensitive poly(lactic acid) (PLA)/nanofibrillated cellulose (NFC) films containing essential oils and anthocyanin for food packaging application

Active and pH-sensitive films of poly(lactic acid) (PLA)/nanofibrillated cellulose (NFC) have been fabricated and tested. The PLA and PLA/NFC films with 1.5% NFC were prepared via solvent casting method, with different loadings of essential oil (EO), including thymol and curry, being added at 5, 10, and 15%. The fixed content of anthocyanin powder (1%) was incorporated into the films as a pH indicator. The active PLA and PLA/NFC films were characterised on their physical, mechanical, thermal, and biodegradation properties. The addition of NFC reduced the tensile strength but increased the flexibility of films due to the plasticizing effect of EOs. The PLA/EO and PLA/NFC/EO films containing curry demonstrated a slightly higher strength than the films with thymol. The flexibility of films was increased at higher loading of EO regardless of the types of EO. The thermal profile demonstrated that the neat PLA film had a higher maximum degradation temperature than the active PLA/EO and PLA/NFC/EO films. The active PLA/EO and PLA/NFC/EO films containing anthocyanin successfully changed its colour in pH 2.0 and 14.0. The PLA/NFC films with thymol and anthocyanin formulation could inhibit fungus growth better in the cherry tomato sample than the PLA/NFC films with curry and anthocyanin.

Study of the volatilization rules of volatile oil and the sustained-release effect of volatile oil solidified by porous starch

Volatile oil from traditional Chinese medicine has various biological activities and has pharmacological activities in the central nervous system, digestive system, cardiovascular system, respiratory system, etc. These oils are widely used in clinical practice. However, the development of their clinical applications is restricted due to the disadvantages of volatile oils, such as high stimulation, high volatility and poor stability. To improve the stability of a volatile oil in the preparation process, its volatilization and stable release must be controlled. In this paper, porous starch was used as a solid carrier material, and liquid volatile oil was solidified by physical adsorption. GC–MS was used to determine the chemical constituents of the volatile oil, solidified powder and tablets, and the volatilization rules of 34 chemical constituents were analysed statistically. The solidified volatile oil/porous starch powder was characterized by XRD, TGA and DSC, and the VOCs of the volatile oil before and after solidification were analysed by portable GC–MS. Finally, the stable release of the volatile oil could be optimized by changing the porous starch ratio in the formulation. Volatilization was shown to be closely related to the peak retention time and chemical composition, which was consistent with the theory of flavour. The physical properties and chemical composition of the volatile oil did not change after curing, indicating that the adsorption of the volatile oil by porous starch was physical adsorption. In this paper, the porous starch-solidified volatile oil had a slow-release effect, and the production process is simple, easy to operate, and has high application value.

Tunisian Pine Essential Oils: Chemical Composition, Herbicidal and Antifungal Properties

The development of resistance against commercialized antifungal and herbicides encourages researchers to focus on the development of new natural products based on essential oils (EOs) with herbicidal and antifungal properties. This study aims to analyze the chemical compositions and evaluate the herbicidal and antifungal activities of cones essential oil of three Pine Tunisian species. EOs composition was carried out by GC and GC/MS analysis. Phytotoxic effects of EOs was evaluated against the germination and growth of two weeds (Phalaris canariensis and Sinapis arvensis) and Triticum durum as cultivated specie. Antifungal assays were evaluated against five fungal strains (Bipolaris sorokiniana, Botrytis cinerea, Fusarium graminarium, Fusarium avenaceum and Fusarium culmorum). Our results showed that pines EOs are characterized by their richness in monoterpenes hydrocarbons (51.71-78.33%) with different dominant constituents. Limonene (3.21-46.56%), α-pinene (28.15-34.52%), and β-pinene (0.95-9.34%) were the major compounds in analyzed EOs. Tested oils were effective against weeds, cultivated specie and target fungi in relation to their variable compositions. All EOs studied showed a significant phytotoxic effects and Pinus pinea exhibited the highest herbicidal effects against all tested weeds. In addition, the highest fungi toxic properties have been marked by P. pinea and P. nigra EOs. Obtained data found that the interspecific variability results in a variability of the chemical composition of pine EOs as well as their biological activities.

Essential Oils of Duguetia Species A. St. Hill (Annonaceae): Chemical Diversity and Pharmacological Potential.

Duguetia A. St. Hill (Annonaceae) is recognized as one of the major genera with approximately 100 species, 67 of which are found in Brazil (29 of those are endemic). They are arboreal species with edible fruits known as “pindaíba”, “pindaíva” “pinha”, and “envira” in Brazil. Many Duguetia species, in particular, have been used in traditional medicine to treat renal colic, stomachache, rheumatism, cough, toothache, muscle pain, fever, gastrointestinal pain, and breathing difficulties. In this study, we reviewed the chemical constituents and pharmacological properties of essential oils (EOs) from Duguetia species. A total of 12 species were found, along with their EO chemical constituents and bioactivities. Bicyclogermacrene, humulene epoxide II, spathulenol, germacrene D, caryophyllene oxide, viridiflorene, α-pinene, β-caryophyllene, and β-pinene were the main chemical constituents reported. The pharmacological effects of Duguetia species EOs included anti-inflammatory, antinociceptive, antibacterial, antifungal, antioxidant, anti-trypanosoma, cytotoxic and antitumor properties. This information adds to our understanding of the potential of the EOs of Duguetia species.

Prolonged repellent activity of Ruta graveolens essential oil adsorbed on different mineral matrices against Sitophilus zeamais (L.) (Coleoptera: Curculionidae)

Plant-derived essential oils (EOs) have been considered as promising alternatives to conventional insecticides. But because of their high biodegradability and rapid volatilization, EOs are not persistent. To overcome this drawback of short protection time, EOs can be adsorbed onto protective mineral matrices to enhance efficiency by slowing down volatilization. This work was aimed at assessing the potential effectiveness of Ruta graveolens L. (Rutaceae) essential oil (RGEO)-adsorbed zeolite (ZEO) and cloisite 20A (C20A) mineral bio-composites in prolonging the odor-driven repellent efficacy of RGEO towards Sitophilus zeamais (L.) (Coleoptera: Curculionidae). Chemical profile of RGEO was identified using GC and GC-MS. Produced bio-composites were physiochemically characterized by FTIR, SEM-EDS, and TGA. The compounds, 2-undecanone (44.7%) and 2-nonanone (30.3%) were the major constituents of RGEO. Repellent action of bio-composites accounting for 50–100% was persisted for 90 d towards S. zeamais adults, whereas the RGEO used without the adsorbents recorded 0% and 44% of repellent potency within 24 h at the lowest and highest concentrations respectively. Given the volatility of RGEO, IR analyses demonstrated successful adsorption and 90-d long persistence of RGEO on both mineral matrices. Micro-/nanostructural architecture of bio-composites ranged from hierarchically porous for ZEO to intercalated platelets for C20A. EDS imaging confirmed the homogenous dispersion of constituent elements of RGEO on both mineral matrices. Bio-composites indicated improved thermal stability in the presence of air flow relative to the neat mineral matrices. Repellent potency of the bio-composites was arranged in the sequence, RGEO-ZEO < RGEO-C20A throughout the 90 d of experimental period. Findings further suggested that formulations based on EOs adsorbed on solid minerals represent a promising strategy in overcoming EOs’ limitations through retaining enough volatility while maintaining their slow release, thereby prolonging the repulsive effect of EOs for use in stored-product protection.

Chitosan/zein films incorporated with essential oil nanoparticles and nanoemulsions: Similarities and differences

The purpose of this study was to prepare chitosan/zein (CS/Zein) edible films reinforced with Mosla chinensis essential oils (EOs) nanoemulsions (NEs) and nanoparticles (NPs) in order to compare their properties. NEs and NPs containing EOs could be used to fabricate films with functional properties, and the films were prepared using a casting method. The influence of EO concentration and mixing methods on the physical, mechanical, and functional properties of the films was investigated. The results indicated that the films formulated with EO NEs generated favorable fundamental and functional characteristics with excellent mechanical properties, moisture barrier capacity, and significant antioxidant and antibacterial activity. In addition, the use of NEs-based films improved the release of bioactive compounds, and the mechanism of EO release was found to follow a first order model. In summary, EO NEs were more effective in preserving the fundamental and functional properties of CS/Zein nanocomposite edible films than NP-based films. These differences may reflect different forms and methods of dispersing EOs in NEs and NPs. This study demonstrated that NEs reinforced films could be used to enhance the effectiveness of EOs in food products and develop new strategies for their delivery and application.

Applications of Essential Oils as Antibacterial Agents in Minimally Processed Fruits and Vegetables—A Review

Microbial foodborne diseases are a major health concern. In this regard, one of the major risk factors is related to consumer preferences for “ready-to-eat” or minimally processed (MP) fruits and vegetables. Essential oil (EO) is a viable alternative used to reduce pathogenic bacteria and increase the shelf-life of MP foods, due to the health risks associated with food chlorine. Indeed, there has been increased interest in using EO in fresh produce. However, more information about EO applications in MP foods is necessary. For instance, although in vitro tests have defined EO as a valuable antimicrobial agent, its practical use in MP foods can be hampered by unrealistic concentrations, as most studies focus on growth reductions instead of bactericidal activity, which, in the case of MP foods, is of utmost importance. The present review focuses on the effects of EO in MP food pathogens, including the more realistic applications. Overall, due to this type of information, EO could be better regarded as an “added value” to the food industry.

The Effect of Volatile Oils on Debonding of Polycarbonate Brackets Reinforced with Ceramic Filler: A Qualitative Study

Introduction: An effective debonding agent should be capable of reducing not only the debonding force, but also the amount of adhesive remaining with no enamel or bracket fracture. Aim: The aim of the present in vitro study was to evaluate the amount of the adhesive remnants, enamel fracture as well as bracket fracture after application of different volatile oils at different time of application using ARI system. Material and Method: Polycarbonate brackets reinforced with ceramic filler were bonded to one hundred and eighty (180) sound extracted human premolars using Transbond XT light curing adhesive. The teeth were then distributed into five groups. Teeth were then de-bonded using the Instron Universal Testing Machine. The enamel surface of debonded teeth and their bracket bases were examined under the stereomicroscope SEM for adhesive remnants (ARI), enamel fracture and bracket fracture. Result: At 5 minutes of application, no significant difference was noticed among volatile oils in all the qualitative results including; adhesive remnants, enamel fracture and bracket fracture. At 5 minutes of application, the peppermint volatile oil exhibited the highest percentage (55%) of score 1 whereas the clove oil revealed the least percentage (15%). At 30 minutes of application, the black seed exhibited the least percentage of score 1 and the highest percentage of score 2 (75%). At 5 minutes, the peppermint oil showed the least brackets fracture (20%) whereas the clove oil was in the second rank (25%) and the mixture of peppermint oil with black seed oil revealed the highest (55%). At 30 minutes, the clove oil showed the least bracket fracture (5%) whereas peppermint oil was in the second rank (20%) and the black seed oil depicted the highest percentage (45%). Conclusion: The present study supported that the 5- minutes of peppermint as well as the black seed volatile oil applications can be considered the best debonding agents whereas the clove oil can be used as a medication or mouthwash before debonding. The latter approach worth further investigations.

Effect of Volatile Oils on De-Bonding of Polycarbonate Bracket Reinforced with Ceramic Filler: A Quantitative Study (Part 1)

Introduction: The introduction of esthetic brackets is a new clinical approach in the field of orthodontics. Two main types of esthetic brackets have been developed and became widely available; the polycarbonate brackets, and the ceramic brackets. Both types have faced two significant de-bonding problems: (1) enamel and bracket fracture. The two problems have been well documented and continue to be of concern to clinicians.&#x0D; Aim: The aim of this in vitro study was to evaluate quantitatively the effect of three volatile oils and their combinations on the de-bonding of ceramic brackets. &#x0D; Material and Method: Polycarbonate brackets reinforced with ceramic filler were bonded to one hundred and eighty (180) sound extracted human premolars using Transbond XT light curing adhesive. The teeth were then distributed into the following groups according to the type of volatile oil and period of application: clove oil (5 &amp; 30 minutes), peppermint oil (5 &amp; 30 minutes), Black seed volatile oil (5 &amp; 30 minutes), and mixture of peppermint + Black seed volatile oils (5 &amp; 30 minutes) in addition to control group. The brackets were then de-bonded using the Instron Universal Testing Machine and the de-bonding force was recorded for each type of the volatile oils in different times of application. &#x0D; Result: The result revealed that the Black seed volatile oil gave the lowest de-bonding force in 5 minutes and 30 minutes of application whereas the mixture of the Black seed oil + peppermint oils gave the highest force in both time of application. Further, the peppermint oil application for 5-minute was found to be in the second rank whereas the Clove oil was in the third rank. Furthermore, in the 30 minutes of application the Clove oil was in the second rank whereas the peppermint was found to be in the third rank and the combination of Black seed oil + peppermint oil shows the highest debonding force.&#x0D; Conclusion: Despite the limitation of the present study result, an assumption has been drawn from the results obtained that (1) the 5- minutes of black seed or peppermint volatile oils application can be considered the best debonding agent compared to the other volatile oils; (2) the clove oil can be used after de-bonding to facilitate the final cleansing-up of enamel surface. To confirm the latter assumption, further investigations are needed.

Antibacterial Activity of the Essential Oil From Litsea cubeba Against Cutibacterium acnes and the Investigations of Its Potential Mechanism by Gas Chromatography-Mass Spectrometry Metabolomics.

Cutibacterium acnes (C. acnes) is an anaerobic Gram-positive bacterium generally considered as a human skin commensal, but is also involved in different infections, such as acne and surgical infections. Although there are a variety of treatments, the side effects and the problem of bacterial drug resistance still limit their clinical usage. In this study, we found that essential oil (EO) distilled from fresh mature Litsea cubeba possessed promising antibacterial activity against C. acnes. In order to elucidate its potential mechanism, bacteriostatic activity test, Live/Dead kit assay, scanning electron microscope (SEM), transmission electron microscope (TEM), and metabolomics were employed. In addition, the content of adenosine triphosphate (ATP) in bacterium and the activities of key enzymes involved in critical metabolic pathways were detected using a variety of biochemical assays. The results showed that EO exhibited significant antibacterial activity against C. acnes at a minimum inhibitory concentration (MIC) of 400 μg/mL and a minimum bactericidal concentration (MBC) of 800 μg/mL, and EO could destroy C. acnes morphology and inhibit its growth. Moreover, results from our study showed that EO had a significant effect on the C. acnes normal metabolism. In total, 86 metabolites were altered, and 34 metabolic pathways related to the carbohydrate metabolism, energy metabolism, amino acid metabolism, as well as cell wall and cell membrane synthesis were perturbed after EO administration. The synthesis of ATP in bacterial cells was also severely inhibited, and the activities of key enzymes of the glycolysis and Wood-Werkman cycle were significantly affected (Pyruvate Carboxylase, Malate Dehydrogenase and Pyruvate kinase activities were decreased, and Hexokinase was increased). Taken together, these results illustrated that the bacteriostatic effect of EO against C. acnes by breaking the bacterial cell morphology and perturbing cell metabolism, including inhibition of key enzyme activity and ATP synthesis. The results from our study may shed new light on the discovery of novel drugs with more robust efficacy.

Comparing the effect of Thymus spp. essential oils on Candida auris

Candida auris is an emergent yeast pathogen responsible for many invasive fungal infections due to its multidrug-resistant character and its huge transmission ability. Essential oils (EOs) obtained from several aromatic plants have been regarded as an alternative treatment upon to fungal infections. For example, Thymus spp. are known by their antifungal effect due to the presence of some volatile compounds in their EOs, such as carvacrol, thymol, linalool and γ-terpinene. So, the main goal of this work was to compare the effect of several EOs from Thymus spp. on C. auris biofilm.The antifungal activity of Thymus vulgaris, Thymus zygis, Thymus satureioides and Thymus mastichina against planktonic cells of C. auris NCPF 8971 was assessed by agar disk diffusion method. The effect of these EOs with direct or vapour phases on preformed biofilms was evaluated by colony-forming units’ enumeration. Importantly it was noticed a completely different range of action between the EOs from the same genus. While T. vulgaris showed the biggest antifungal effect with a halo of 59.75 ± 15.75 mm, T. mastichina for the other side, presented a halo of 13.13 ± 1.36 mm, showing a very low activity. In addition, the direct application of T. vulgaris and T. zygis EOs demonstrated higher antifungal activity against C. auris biofilms than vapour phase application. However, T. vulgaris also showed significant action in the vapour phase mode. The chemical composition of Thymus EOs was analysed by GC and GC-MS, and was demonstrated that they have different chemical profiles, namely in the amount of phenolic compounds, which justify the different antifungal actions.In conclusion, T. vulgaris and T. zygis oils, can be pointed out as a great contribution to the treatment of C. auris infections, being promising alternatives to conventional therapy. However, the efficiency of the EOs differs substantially between the four species of Thymus. Therefore, the selection of natural therapies should always have in account EOs composition.