Chemical composition, seasonal variation and antiaging activities of essential oil from Callistemon subulatus leaves growing in Egypt.

Callistemon is an aromatic genus of flowering plants belonging to family Myrtaceae. The essential oils of C. subulatus leaves were collected in four seasons and analyzed using GC/MS. The oils demonstrated monoterpenes as the predominant class. Eucalyptol was the main component in all seasons; summer (66.87%), autumn (58.33%), winter (46.74%) and spring (44.63%), followed by α-pinene; spring (31.41%), winter (28.69%), summer (26.34%) and autumn (24.68%). Winter oil, the highest yield (0.53 mL/100g), was further investigated for its inhibitory activity against enzymes associated with ageing; elastase and acetylcholinesterase. It remarkably inhibited elastase and acetylcholinesterase with IC50 values of 1.05 and 0.20 µg/ml, respectively. A molecular docking study was conducted for the major oil components on the active sites of target enzymes. Eucalyptol revealed the best binding affinity for both enzymes. C. subualtus oil could be used as supplement for management of ageing disorders like skin wrinkles and dementia.

Chemical Variation and Environmental Influence on Essential Oil of Cinnamomum camphora.

Cinnamomum camphora is a traditional aromatic plant used to produce linalool and borneol flavors in southern China; however, its leaves also contain many other unutilized essential oils. Herein, we report geographic relationships for the yield and compositional diversity of C. camphora essential oils. The essential oils of 974 individual trees from 35 populations in 13 provinces were extracted by hydrodistillation and analyzed qualitatively and quantitatively by gas chromatography-mass spectrometry and gas chromatography-flame ionization detection, respectively. Oil yields ranged from 0.01% to 3.46%, with a significantly positive correlation with latitude and a significantly negative correlation with longitude. In total, 41 compounds were identified, including 15 monoterpenoids, 24 sesquiterpenoids, and two phenylpropanoids. Essential oil compositions varied significantly among individuals and could be categorized into various chemotypes. The six main chemotypes were eucalyptol, nerolidol, camphor, linalool, selina, and mixed types. The other 17 individual plants were chemotypically rare and exhibited high levels of methyl isoeugenol, methyl eugenol, δ-selinene, or borneol. Eucalyptol-type plants had the highest average oil yield of 1.64%, followed in decreasing order by linalool-, camphor-, mixed-, selina-, and nerolidol-type plants. In addition, the five main compounds exhibited a clear geographic gradient. Eucalyptol and linalool showed a significantly positive correlation with latitude, while selina-6-en-4-ol was significantly and negatively correlated with latitude. trans-Nerolidol and selina-6-en-4-ol showed significantly positive correlations with longitude, whereas camphor was significantly and negatively correlated with longitude. Canonical correspondence analysis indicated that environmental factors could strong effect the oil yield and essential oil profile of C. camphora.

Multivariate Analysis of Essential Oil Composition of Artemisia annua L. Collected from Different Locations in Korea.

Artemisia annua L. is distributed throughout the world and it is an important medicinal plant in Korea to treat various human diseases. Recently, A. annua has also been considered to be an effective ethnobotanical drug against COVID-19. A. annua contains an appreciable amount of essential oil with different biological properties. However, the composition of essential oils in aromatic plants can be varied depending on several factors, including geographic, genetic, ecological, etc. Hence, the present study aimed to investigate the chemical diversity of essential oils of Korean A. annua collected from different locations in Korea by multivariate analysis. For this purpose, the seeds of A. annua were collected from 112 different locations in Korea and were grown under the same environmental conditions. Except for nine individuals which decayed during the cultivation, essential oils were isolated from the aerial parts of 103 A. annua individuals (AEOs) using the steam distillation extraction method, and their chemical compositions were determined by GC-MS analysis. Furthermore, a multivariate analysis was performed to distinguish the difference between 103 individuals of A. annua based on their essential oil compositions. The yield of A. annua essential oils ranged from 0.04 to 1.09% (v/w). Based on the GC-MS data, A. annua individuals were grouped into six chemotypes such as artemisia ketone, camphor, ß-cubebene, eucalyptol, α-pinene, and ß-selinene. The multivariate analysis results revealed that Korean A. annua could be largely grouped into three clusters such as artemisia ketone, eucalyptol, and ß-selinene. Among 35 components selected for principal component analysis (PCA), PC1, PC2, and PC3 accounted for 82.55%, 8.74%, and 3.62%, respectively. Although all individuals of A. annua were cultivated under the same environmental conditions, there is an intraspecific chemical diversity that exists within Korean native species.

Chemical composition, in vitro and in silico evaluation of essential oil from Eucalyptus tereticornis leaves for lung cancer.

Chemical composition of the essential oil (EO) of Eucalyptus tereticornis leaves was studied by gas chromatography-mass spectrometry. Forty-five constituents were identified in the oil hydrodistilled from the sample collected from Ghudda Village, Bathinda (Pb), India of which eucalyptol (34.39%) and ledol (9.92%) were the major constituents. In vitro antioxidant and anticancer potential of EO was analysed by DPPH 2,2-diphenylpicrylhydrazyl (DPPH) and MTT assay. The percentage free radical scavenging activity was found to be 63.77%. The antiproliferative activity was analysed using MTT assay in adenocarcinomic human alveolar basal epithelial A549 cancer cell line and showed IC50 value of 47.14 µg/ml. In silico study of EO, constituents were performed using Maestro 12.9 against EGFR (PDB ID-2RGP). Five constituents from EO showed high dockscore as compared to standard Mobicertinib which indicated the effectiveness of oil constituents against lung cancer.

A GC-MC analysis of chemical compounds and identification of the antibacterial characteristics of the essential oil of two species exclusive to Iranian habitats: New chemotypes.

BACKGROUND: The diversity found in the chemical compounds of a single species in different regions results in different biologic characteristics which can be considered as a strong source for identifying new chemotypes. Hymenocrater incanus Bunge and Dracocephalum kotschyi Boiss. are exclusive species of the Lamiaceae family which grow in the western and central habitats of Iran. This study was designed and carried out to determine the yield, identify the chemical compounds, and evaluate the antimicrobial characteristics of the essential oil (EO) of these two species in Iran for the first time. METHODS: The flowering twigs of the species D. kotschyi and H. incanus were collected from the villages of Totmach and Kamu in Isfahan province respectively, in May 2019. The EO of these plants was extracted and separated using the water distillation method, utilizing the Clevenger device. The EO compounds were analyzed using a gas chromatograph coupled with a mass spectrometer (GC-MS). The evaluation of antimicrobial characteristics was carried out by determining the growth inhibition zone implementing the Agar method, the minimum inhibition concentration (MIC), and the minimum bactericidal/fungicidal concentration (MFC/MBC) utilizing liquid dilution culture. RESULTS: The results indicated that the highest yield belonged to the EO of D. kotschyi at %2.6 (w/w). In this EO there were citral (%25.44), neral (%20.87), α-pinene (%14.48), trans-geranic acid methyl ester (%9.74), and D-limonene (%6.87). Moreover, H. incanus had the dominant compounds (-)-Spathulenol (%12.61), caryophyllene (%10.00), linolenic acid (%8.54), 1,8-cineole (%5.95), palmitic acid (%5.35), and α-cadinol (%5.17). The largest diameter of growth inhibition zone belonged to the H. incanus EO against the Gram-positive bacteria S. pyogenes (~17.67mm). The strongest inhibition activities in the form of growth inhibition diameter exhibited by the D. kotschyi EO were against the Gram-negative bacteria S. paratyphi-A serotype (~ 12 mm), K. pneumoniae, and Sh. dysenteriae (~ 11 mm) which was significant compared to the Gram-positive rifampin (~ 8 mm). CONCLUSIONS: It can be seen that these species are new chemotypes with special and novel chemical compounds which can potentially be used to manufacture natural antibiotics against some bacterial strains.

Comprehensive two-dimensional gas chromatographic platforms comparison for exhaled breath metabolites analysis.

The high potential of exhaled breath for disease diagnosis has been highlighted in numerous studies. However, exhaled breath analysis is suffering from a lack of standardized sampling and analysis procedures, impacting the robustness of inter-laboratory results, and thus hampering proper external validation. The aim of this work was to verify compliance and validate the performance of two different comprehensive two-dimensional gas chromatography coupled to mass spectrometry platforms in different laboratories by monitoring probe metabolites in exhaled breath following the Peppermint Initiative guidelines. An initial assessment of the exhaled breath sampling conditions was performed, selecting the most suitable sampling bag material and volume. Then, a single sampling was performed using Tedlar bags, followed by the trapping of the volatile organic compounds into thermal desorption tubes for the subsequent analysis using two different analytical platforms. The thermal desorption tubes were first analyzed by a (cryogenically modulated) comprehensive two-dimensional gas chromatography system coupled to high-resolution time-of-flight mass spectrometry. The desorption was performed in split mode and the split part was recollected in the same tube and further analyzed by a different (flow modulated) comprehensive two-dimensional gas chromatography system with a parallel detection, specifically using a quadrupole mass spectrometer and a vacuum ultraviolet detector. Both the comprehensive two-dimensional gas chromatography platforms enabled the longitudinal tracking of the peppermint oil metabolites in exhaled breath. The increased sensitivity of comprehensive two-dimensional gas chromatography enabled to successfully monitor over a 6.5 h period a total of 10 target compounds, namely α-pinene, camphene, ß-pinene, limonene, cymene, eucalyptol, menthofuran, menthone, isomenthone, and neomenthol.

Peppermint protocol: first results for gas chromatography-ion mobility spectrometry.

ThePeppermint Initiativeseeks to inform the standardisation of breath analysis methods. FivePeppermint Experimentswith gas chromatography-ion mobility spectrometry (GC-IMS), operating in the positive mode with a tritium3H 5.68 keV, 370 MBq ionisation source, were undertaken to provide benchmarkPeppermint Washoutdata for this technique, to support its use in breath-testing, analysis, and research. Headspace analysis of a peppermint-oil capsule by GC-IMS with on-column injection (0.5 cm3) identified 12 IMS responsive compounds, of which the four most abundant were: eucalyptol;ß-pinene;α-pinene; and limonene. Elevated concentrations of these four compounds were identified in exhaled-breath following ingestion of a peppermint-oil capsule. An unidentified compound attributed as a volatile catabolite of peppermint-oil was also observed. The most intense exhaled peppermint-oil component was eucalyptol, which was selected as a peppermint marker for benchmarking GC-IMS. Twenty-five washout experiments monitored levels of exhaled eucalyptol, by GC-IMS with on-column injection (0.5 cm3), att= 0 min, and then att+ 60,t+ 90,t+ 165,t+ 285 andt+ 360 min from ingestion of a peppermint capsule resulting in 148 peppermint breath analyses. Additionally, thePeppermint Washoutdata was used to evaluate clinical deployments with a further five washout tests run in clinical settings generating an additional 35 breath samples. Regression analysis yielded an average extrapolated time taken for exhaled eucalyptol levels to return to baseline values to be 429 ± 62 min (±95% confidence-interval). The benchmark value was assigned to the lower 95% confidence-interval, 367 min. Further evaluation of the data indicated that the maximum number of volatile organic compounds discernible from a 0.5 cm3breath sample was 69, while the use of an in-line biofilter appeared to reduce this to 34.

Profiling of the essential oil compositions from the flowers and leaves of Tanacetum fisherae Aitch. & Hemsl., an endemic plant in Kerman province, Iran.

Tanacetum fisherae Aitch. & Hemsl. is an endemic plant growing wild in some brackish regions of Iran. Since there are not enough reports concerning the quantitative and qualitative analyses of its essential oil, it was decided to characterise the respective water-distilled oils obtained from the flowers and leaves of this medicinal plant. Characterisation of the corresponding essential oil profiles revealed that in both of the analysed oils, oxygenated monoterpenes constituted most of the chemical profiles. In this sense, the most prevailing natural compounds in the flower oils were cis-p-2-menthen-1-ol (11.2%), trans-p-2-menthen-1-ol (10.7%), trans-piperitol (7.8%), 1,8-cineole (6.1%), cis-piperitol (3.8%), α-terpineol (3.7%) and terpinene-4-ol (2.1%), whereas the main constituent components of the leaves oils were, respectively, 1,8-cineole (16.7%), cis-p-2-menthen-1-ol (14.6%), trans-p-2-menthen-1-ol (10.4%), trans-piperitol (12.8%), α-terpineol (5.4%), cis-piperitol (2.9%), borneol (2.7%), and terpinene-4-ol (2.1%). In addition, the second rank of natural compound constituting groups was due to oxygenated sesquiterpenes, as well.[Formula: see text].

Chemical composition and antibacterial activity of the essential oil of Laurus nobilis leaves.

Chemical composition determination and in vitro antibacterial effect of Essential Oil (EO) of Laurus nobilis leaves grown North West Algerian conditions were investigated. Antibacterial activity was evaluated by the technique of the paper disc diffusion. Extractions were carried out with Clevenger apparatus and EO compositions were investigated by gas chromatography coupled to mass spectrometry (GC-MS) analysis. The oxygenated monoterpenes (MO) were the class with the highest contents, represent 59% of the EO. A total of twenty-seven of these compounds were identified, the major components were 1,8-cineole (30.1%), α-terpynil acetate (21.6%), methyl eugenol (16.9%) of the total oil. The highest antibacterial power of the EO tested was recorded in Streptococcus faecalis and Staphylococcus aureus with the zone diameter of inhibition 13.6 and 11.2 mm respectively and a minimal inhibitory concentration (MIC) of 0.25 mg/mL for both these two strains.

Oral administration of eucalyptol reduces cell migration and pain-like behavior in zymosan-induced arthritis mice

Abstract Rheumatoid arthritis (RA) is an inflammatory disease that utilizes nonbiologic and biologic drugs for appropriate disease management. However, high cost, adverse effects, reduced effectiveness, and risk of infection have stimulated the search for safer and more efficacious therapeutic strategies. In the present study, we aimed to evaluate the anti-inflammatory and analgesic properties of eucalyptol in an experimental model of arthritis. Mice were administered zymosan or saline intra-articularly. One hour before the zymosan administration, the mice were treated with oral eucalyptol (200-400 mg/kg) and vehicle. Cell influx, neutrophils, lymphocytes, and monocytes were measured in joint exudates. Joint pain was assessed using paw-pressure tests. Orally administered eucalyptol (200 and 400 mg/kg) significantly reduced cell influx, as well as neutrophils, lymphocytes, and monocytes, when compared with the control. Eucalyptol at a dose of 400 mg/kg significantly reversed joint pain and demonstrated analgesic activity (60%); however, 200 mg/kg failed to alter joint pain. These results indicate that oral eucalyptol promotes anti-inflammatory and analgesic activity in mice subjected to zymosan-induced arthritis.

Minty aroma compounds in red wine: Development of a novel automated HS-SPME-arrow and gas chromatography-tandem mass spectrometry quantification method.

A novel automated method was developed for the quantitative determination of nine terpenoids that could contribute to the minty notes of red wine bouquet. The method couples headspace SPME-Arrow extraction with GC-MS/MS analysis. PDMS/DVB fiber was chosen for the extraction and an ionization energy of 30 eV permitted to optimize the analyte detection. The optimal sample preparation consists of a two-fold dilution of the wine sample with addition of 4 g of sodium chloride while the most suitable extraction conditions take place at 50 °C for 1 h. The method shows good linearity, intraday variations between 2 and 25%, interday variations between 7 and 23% and recoveries between 80 and 119%. The method exhibits the required low detection (between 3 and 60 ng/L) and quantification (between 6 ng/L and 200 ng/L) limits. These limits have permitted the quantification of the pool of minty terpenoids in fourteen red Bordeaux wines.

Chemical composition and biological activities of an essential oil from the aerial parts of Artemisia Gmelinii weber ex Stechm.

The aerial parts of Artemisia gmelinii Weber ex Stechm were collected from the northeast of China. The essential oil was obtained by hydrodistillation and analysed by GC-MS. A set of 66 compounds were identified representing 99.1% of the oil composition. The major compounds in the oil were cyclobutaneethanol, endo-borneol, germacrene D, eucalyptol, selin-6-en-4α-ol, bisabolone oxide A, caryophyllene and terpinen-4-ol. Moreover, the essential oil was evaluated for its antioxidant, antidiabetic, and anticholinesterase activities in vitro. Additionally, the antioxidant potential of the oil was evaluated using DPPH and ABTS assays. The oil showed good antidiabetic activity with an IC50 of 63.2 µg/mL, which was similar to that of the positive control acarbose, and weak anticholinesterase activities. These findings demonstrated that the essential oil of Artemisia gmelinii may be a good natural antidiabetic.

Real-time breath analysis of exhaled compounds upon peppermint oil ingestion by secondary electrospray ionization-high resolution mass spectrometry: technical aspects.

Breath analysis by secondary electrospray ionization high-resolution mass spectrometry (SESI-HRMS) has potential for clinical diagnosis and drug monitoring. However, there is still a lack of benchmarking data that shows the capability of this technique and allows comparability with other breath analysis techniques. In this regard, the goal of this study was the identification of volatile compounds upon ingestion of a specific peppermint oil capsule to get benchmark data for real-time breath analysis with SESI-HRMS. This was done in the framework of a consortium set up by the International Association of Breath Research (IABR), aimed at comparing several analytical instruments for breath analysis. Breath temporal profiles of two subjects were analyzed with SESI-HRMS before and after ingestion of a peppermint oil capsule. The measurements were performed at two different locations using identical SESI-HRMS platforms to allow for comparability and benchmarking. Remarkably, along with the four major compounds (monoterpenes/cineole, menthone, menthofuran and menthol) reported by other members of the consortium, we detected 57 additional features significantly associated (ρ > 0.8) with the peppermint oil capsule, suggesting that this relatively simple intervention might trigger a more complex metabolic cascade than initially expected. This observation was made on both sites. Additional replicate experiments for one of the subjects suggested that a core of 35-40 unique molecules are consistently detected in exhaled breath upon ingestion of the capsule. In addition, we illustrate the analytical capabilities of real-time SESI-HRMS/MS to assist in the identification of unknown compounds. The results outlined herein showcase the performance of SESI-HRMS and enable comparison with other breath analysis techniques. Along with that, they strengthen the potential of this analytical technique for non-invasive drug monitoring and clinical diagnostic purposes.

Magnoliae Flos Essential Oil as an Immunosuppressant in Dendritic Cell Activation and Contact Hypersensitivity Responses.

Magnoliae Flos is a commonly used traditional medicinal material in Asia. It is used to treat sinusitis, nasal congestion, and hypersensitive skin. Because Magonlia Flos was described as an aromatic material in ancient Chinese texts, we hypothesized that its essential oil may be used to treat immune disorders. Dendritic cells (DCs), regarded as a major target of immunomodulators to control immune responses, play a critical role in the adaptive immune response. In this study, Magnoliae Flos essential oil (MFEO) decreased the production of the cytokines TNF-α, IL-6, and IL-12p70 in lipopolysaccharide (LPS)-stimulated DCs. It also suppressed the surface markers MHC II, CD80, and CD86 in LPS-stimulated DCs. Animal models demonstrated that the 2,4-Dinitro-1-fluorobenzene (DNFB) inducing a contact hypersensitivity response was inhibited following treatment with MFEO. In addition, MFEO inhibited the infiltration of T cells in the ears of DNFB-induced mice. To explore its bioactive compounds, the components of MFEO were analyzed using gas chromatography (GC) and GC-mass spectrometry. The results revealed that the major compounds in MFEO are camphor and 1,8-cineole. Additional DC bioassays confirmed that these compounds substantially suppressed cytokine production in LPS-induced DCs. Therefore, we demonstrated that MFEO exhibits an immunosuppressive effect both in vivo and in vitro, and camphor and 1,8-cineole may be the major components responsible for its immunosuppressive ability. The findings indicate that MFEO has the potential to be developed as a new immunosuppressant for excessive diseases.

Sedative effects of the essential oil from the leaves of Lantana camara occurring in the Republic of Benin via inhalation in mice.

Lantana camara Linn. (Verbenaceae) is used traditionally for its numerous medicinal properties such as antimalarial, antibacterial, anticancer and anti-inflammatory. In the present study, we investigated the chemical composition of essential oil from the leaves of L. camara (LCEO) occurring in the Republic of Benin (West Africa) in comparison with LCEOs from other regions; evaluated its sedative effects in mice via inhalation administration; and identified the compounds responsible for activity. LCEO was extracted by hydrodistillation and chemical analyses of the oil were performed by GC and GC/MS. The oil was dominated by monoterpene hydrocarbons (60.58%) and oxygenated monoterpenes (33.39%), among which sabinene (38.81%) and 1,8-cineole (28.90%) were the most abundant. LCEO administered via inhalation to mice significantly decreased locomotor activity in a dose-dependent manner, mainly at the doses of 0.0004 and 0.04 mg per 400 µL of triethyl citrate (TEC). The oil was fractionated to give two fractions, which were further investigated, and revealed that both sabinene and 1,8-cineole were the principal active compounds. The results of the present study indicated that via inhalation administration, LCEO and its main constituents could be considered as promising candidates for the management of dementia, insomnia, attention deficit hyperactivity disorder and other central nervous system-associated diseases.

Evaluation of the volatile composition, toxicological and antioxidant potentials of the essential oils and teas of commercial Chilean boldo samples.

Chilean boldo (Peumus boldus Molina) is the boldo species most consumed around the world. Digestive and hepatobiliary disorders represent the main targets of its action. This work aims to characterize the volatile chemical composition, toxicological, and antioxidant potentials of the essential oils and teas of commercial samples of Chilean boldo packed on sachets [Group 1 (G1): five samples] or in plastic bags [Group 2 (G2): five samples]. Fifty-three compounds have been identified in the essential oils of commercial samples of Chilean boldo from Brazil, while only twelve compounds have been found in the volatile fraction of their infusions. Terpineol, 1,8-cineole, and p-cymene are the major compounds of essential oils. Terpineol is also the major compound of the volatile fraction of teas, followed by limonene dioxide. The presence in all samples of the chemical markers p-cymene, 1,8-cineole, ascaridole, and boldine suggests that they are genuine. The teas offer a better antioxidant capacity than essential oils, thereby indicating that antioxidant activity is concentrated in the non-volatile fraction of these herbs. All LD50 values estimated for the essential oils are below 200 ppm, thus indicating that the oils are highly cytotoxic. G1 and G2 appear to be very similar with respect to all the parameters analyzed. This similarity may indicate a single source for these products.

Exploring of bioactive compounds in essential oil acquired from the stem and root derivatives of Hypericum triquetrifolium callus cultures.

The chemical profile of the essential oil of callus and cell suspension cultures derivatives from stem and root of Hypericum triquetrifolium were explored by ITEX/GC-MS. The major constituents for stem derivatives were undecane (78.44%) and 2,4,6-trimethyl-octane (9.74%) for fresh calli, 2,4-dimethyl-benzaldehyde (46.94%), 2,3-dimethyl-undecane (28.39%), 2,4-dimethyl-1-hexene (10.17%), 1,2-oxolinalool (3.64%) and limonene (3.55%) for dry calli and undecane (61.24%), octane, 2,4,6-trimethyl- (16.73%), nonane, 3-methyl-(3.74%), 2,5-diphenyl-benzoquinone (3.70%) and limonene (3.60%) for cell suspension. However, for root derivatives, the dominated components were: undecane (49.94%), eucalyptol (12.07%), limonene (9.98%), toluene (9.03%) and 3-methyl-nonane (4.29%) for fresh calli, 2,4-dimethyl-benzaldehyde (29.80%), 1,1-dimethylethyl-cyclohexane (14.99%), 3-methyl-pentanal (14.99%), undecane (10.04%), beta-terpinyl acetate (8.60%), 1,2-oxolinalool (6.27%) and 2-pentyl-furan (4.09%) for dry calli, undecane (52.38%), 2,4,6-trimethyl-octane (13.81%), 3-methyl-nonane (5.73%), toluene (4.82%) and limonene (4.57%) for cell suspension derivative in root. The attained outcomes indicated that the alkane, aldehyde and monoterpene fractions dominated the chemical composition of essential oils.

Chemical composition and antimicrobial activity of the essential oil of Tanacetum walteri (Anthemideae-Asteraceae) from Iran.

The composition and antimicrobial activity of the essential oil of Tanacetum walteri were studied. Aerial flowering parts of plant were collected from North Khorasan Province of Iran and the essential oil was isolated by hydrodistillation and analysed by GC-FID and GC-MS. Antimicrobial activity of the essential oil was determined by disc diffusion and MIC and MBC determination. Thirty-five compounds were identified in the oil of T. walteri accounting for 94.4% of the total oil. Thymol (22.5%), 1,8-cineole (8.2%), umbellulone (6.9%), α-bisabolol (6.3%) and camphor (5.3%) were as the principal constituents. The highest antimicrobial activity of the essential oil was observed against Staphylococcus aureus, Enterococcus faecalis and Klebsiella pneumoniae with MIC value of 0.63 mg/mL. The inhibitory effect of the essential oil of T. walteri could be attributed mainly to the high levels of phenolic compound thymol and oxygenated terpenes in essential oil.

In vitro efficacy of essential oils with different concentrations of 1, 8-cineole against Rhipicephalus (Boophilus) microplus / Eficácia in vitro de óleos essenciais com diferentes concentrações de 1, 8-cineol contra Rhipicephalus (Boophilus) microplus

Abstract The aim of this study was to evaluate the acaricidal activity of essential oils from three species of plants with intermediary concentrations of 1,8-cineole against the tick species Rhipicephalus (Boophilus) microplus. For this purpose, five serial concentrations (100.0, 50.0, 25.0, 12.5, 6.2 mg/mL) of essential oils from Mesosphaerum suaveolens (L.) Kuntze, Ocimum gratissimum L. and Alpinia zerumbet (Pers.) B. L. Burtt & R. M. Sm. were used on larval packet and adult immersion tests. The essential oils were analysed by gas chromatography-mass spectrometry (GC/MS) and gas chromatography-flame ionization detection (GC-FID), being detected 35.8, 24.7 and 24.0% of 1.8-cineol in the oils of M. suaveolens, O. gratissimum and A. zerumbet, respectively. The lethal concentration (LC 50) of each oil for larvae and engorged females was calculated through Probit analysis. All essential oils showed high efficacy (≥ 95.0%) on engorged females at the 100.0 mg/mL concentration. In regards to larvae, O. gratissimum (LC 50 = 11.9 mg/mL) was the most potent, followed by the A. zerumbet (LC50 = 19.7 mg/mL) and the M. suaveolens (LC50 = 51.6 mg/mL) essential oils. These results show that other compounds interfere with 1,8-cineole action.

Resumo O objetivo deste estudo foi avaliar a atividade acaricida de óleos essenciais de três espécies de plantas com concentrações intermediárias de 1,8-cineol contra o carrapato Rhipicephalus (Boophilus) microplus . Dessa forma, cinco concentrações diferentes (100,0; 50,0; 25,0; 12,5; 6,2 mg/mL) de óleos essenciais de Mesosphaerum suaveolens (L.) Kuntze , Ocimum gratissimum L. e Alpinia zerumbet (Pers.) B. L. Burtt & R. M. Sm. foram avaliadas pelos testes de pacote de larvas e de imersão de adultos. Os óleos essenciais foram analisados pela cromatografia gasosa acoplada a espectometria de massa (GC/MS) e cromatografia gasosa acoplada a detector de ionização de chama (GC-FID), sendo detectados 35,8, 24,7 e 24,0% de 1,8-cineol nos óleos de M. suaveolens, O. gratissimum e A. zerumbet , respectivamente. A concentração letal (CL50) de cada óleo essencial para larvas e fêmeas ingurgitadas foi calculada por meio da análise de Probit. Todos os óleos essenciais na concentração de 100,0 mg/mL apresentaram elevada eficácia (≥ 95,0%) sobre fêmeas ingurgitadas. Com relação as larvas, o óleo essencial de O. gratissimum (CL50 = 11,9 mg/mL) foi o mais potente, seguido pelos óleos de A. zerumbet (LC50 = 19,7 mg/mL) e M. suaveolens (LC50 = 51,6 mg/mL). Estes resultados demonstram que outros compostos interferem na eficácia de 1,8-cineol.