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In Morocco, oregano is one of the most valued aromatic and medicinal plants, widely used for various culinary and therapeutic purposes. Since some Moroccan oregano populations are threatened by extinction, we analyzed the germination behavior of different Origanum species cultivated in the experimental station of INRA in Morocco, in order to plan a subsequent preservation, rehabilitation and domestication programs. In this context, we tested under laboratory conditions the influence of different pretreatments (soaking in distilled water for 24 and 48 hours and soaking in boiling water for 5 minutes) on seed germination of five Origanum species cultivated in the Annoceur experimental station of INRA, namely O. compactum, O. elongatum, O. vulgare subsp. virens, O. vulgare subsp. vulgare and O. onites. Results showed that germination percentage varied significantly according to species and pretreatment. Soaking seeds in distilled water (24 and 48 hours) was more effective in improving the germination rate of all species. O. onites and O. elongatum showed the highest germination rate, 90% and 83% respectively for seeds soaked in distilled water for 24 hours. However, soaking the seeds in boiling water significantly reduced the germination rate of 4 species: O. elongatum, O. vulgare subsp. virens, O. onites and O. vulgare subsp. vulgare (Spain). It should be noted that soaking the seeds in distilled water not only increased the germination rate, but also reduced the latency time of these seeds. According to the treatments used in this study, soaking of seeds in distilled water for 24 and 48 hours can be recommended as the most effective treatment for enhancing germination of Origanum seeds. These data may serve as guidelines for species-specific sexual multiplication protocols, promoting ex situ conservation of these medicinal species.

The neonicotinoid insecticide imidacloprid has been linked to significant reproductive damage in mammals. Origanum majorana essential oil (OME) is a natural herbal product used in the management of many diseases due to its strong antioxidant effects. The oil was hydrodistilled from O. Majorana and analyzed using GC/MS then its possible protective mechanisms against IMI-induced reprotoxicity in male rats were investigated. 28-adult male Wistar rats were divided into 4 groups as follows: group (1) control group, group (2) OME, group (3) IMI, and group (4) IMI + OME. The treatments were applied daily via oral gavage for 60 days. Remarkable abnormalities in both territorial aggressive and sexual behaviors were observed in IMI-treated rats with a significant elevation of serum FSH and LH as well as altered testicular redox status. Along with inhibition of the testicular expression of StAR and aromatase genes and serum total testosterone in addition to abnormal sperm count, viability, motility, and morphology. Histopathological examination showed severe degeneration and necrosis in both germ cells and Leydig cells with atrophy in most of the seminiferous tubules. Co-administration of OME with IMI notably improved all the above-mentioned studied parameters, and restored rats’ spermatogenesis, sexual behavior, and favorably modulates the levels of both testosterone and gonadotropic hormones via its potent antioxidant effect. These findings support the use of OME as a fertility enhancer and suggest that it could be used to manage pesticide-induced male infertility.

Statement of the Problem: There are global efforts for introducing a new herbal antimicrobial agent with minimal side effects. There are some reports about the antimicrobial properties of Pimpinella anisum and Oregano Vulgare. Purpose: In this study, the antimicrobial properties of Pimpinella anisum and Oregano Vulgare have been assessed. Material and Method: In this experimental in vitro study, the dental plaque samples were collected from children aged 3 to 5 years old who were referred to a private dental office with diagnosis of dental caries. After determination of the bacterial colonies of Streptococcus sanguinis, Streptococcus mutans and Streptococcus salivarius, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethanolic and methanolic extracts of Pimpinella anisum and Oregano vulgare were measured by macrodilution and microdilution methods. Results: The mean MIC and MBC of Pimpinella anisum extract and Oregano vulgare extract and their combination against Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius were statistically different (p< 0.001). The combination of these extracts showed the lowest MIC and MBC. Conclusion: Hydroalcoholic extracts of the Pimpinella anisum and Oregano Vulgare were effective antibacterial agent against Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguinis so the combination of these two extracts showed the highest antibacterial properties on all the bacteria evaluated.

Background and Aim: The aim of this study was to investigate the effect of Origanum vulgare administration on testicular injury induced by torsion/detorsion . Materials and Methods: In this experimental study, 64 adult rats were divided into 8 equal groups, as following:1-Sham: the abdominal cavity was opened and then closed. 2.Torsion/detorsion: the rats underwent spermatic cord twisting for 4 hours and then untwisting (30 minutes before untwisting normal saline was injected). 3.Torsion/detorsion+ Origanum vulgare: Similar to group 2, the only difference was injections of Origanum vulgare with different doses (400 mg/kg, 250, 100) which were given to 3 separate groups. 4. Origanum vulgare recipient: without any surgery, injections of Origanum vulgare were given to 3 separate groups with different doses (400 mg/kg, 250, 100). Twenty-four hours after surgery, blood samples were taken to measure oxidative stress factors. Testicular tissue was removed for assessment of histological changes, and the epididymis tissue was used to measure sperm parameters. Data were analyzed by SPSS software. Results: We found significant decreases in Johnson's score, epithelium height, and seminiferous tubule diameter (data obtained from histological examination), number and morphology of sperm parameters and oxidative stress factors (Malondialdehyde, Superoxide dismutase, Glutathione Peroxidase and, Catalase) in the torsion/detorsion group compared to those in the sham group (P= 0.0001), while they improved in the torsion/detorsion groups receiving Origanum vulgare group compared to those in the torsion/detorsion group, but in most cases, the results were not significant. Conclusion: It seems that Origanum vulgare can partially reduce the damage caused by testicular torsion/detorsion.

الملخص: أهداف البحث: تهدف هذه الدراسة إلى صياغة هلام الأسنان أورجانوم فالجاري الجديد المضاد للتسوس مع فاعلية عالية في مضادات الميكروبات. طرق البحث: تم استخراج الزيت العطري أورجانوم فالجاري باستخدام التقطير المائي؛ واستخراج الإيثانول، واللوني للغاز/قياس الطيف الكتلي، وطرق الكروماتوغرافيا السائلة عالية الأداء. وتم تحديد النشاط المضاد للميكروبات للهلام المنتج بزيت الأوريجانو والمستخلص بطريقة الانتشار القرصي. وتم اختبار فعالية الزيت العطري أورجانوم فالجاري في المختبر من أجل الفلم الحيوي للعقدية الطافرة باستخدام التحليل اللوني. النتائج: منع زيت أورجانوم فالجاري العطري من نمو الفلم الحيوي للعقدية الطافرة بنسبة ٩٨٪ مقارنة ببكتيريا التحكم غير المكشوفة. وتمت صياغة خمس عينات من الجل المضاد للتسوس باستخدام زيت الأوريجانو الأساسي والمستخلص. بناء على نتائج الدراسة الميكروبيولوجية، أظهرت عينات الهلام الأولى والثالثة نشاطا عاليا لمضادات الميكروبات ضد السلالات البكتيرية موجبة الجرام من المكورات العنقودية الذهبية والعصوية الرقيقة وفطريات المبيضة البيضاء ونشاطا معتدلا مضادا للميكروبات ضد السلالات سالبة الجرام من الإشريكية القولونية والزائفة الزائفة. الاستنتاجات: بناء على نتائج هذه الدراسة، يمكن اعتبار عينة الهلام الثالثة بمثابة مادة هلامية مضادة للتسوس نظرا لارتفاع نشاطها المضاد للميكروبات. تتميز هذه العينة بخصائص حسية جيدة مقارنة بالعينات الأخرى، وتحمل نشاطا مضادا للميكروبات مرتفعا نسبيا وتحمي من الأغشية الحيوية المسببة للسرطان من العقدية الطافرة. Abstract: Objectives: This study aims to formulate a new Origanum vulgare anti-caries dental gel with high antimicrobial activity. Methods: O. vulgare essential oil was extracted using hydro-distillation, ethanol extraction, gas chromatography/mass spectrometry, and high-performance liquid chromatography methods. Antimicrobial activity of the produced gels with oregano oil and extract was determined through the disco-diffusion method. The effectiveness of O. vulgare essential oil was tested in vitro for Streptococcus mutans biofilm using colorimetric analysis. Results: O. vulgare essential oil inhibited the growth of S. mutans biofilm by 98% compared with unexposed control bacteria (p

Introduction: In order to prevent increased bacterial resistance, it is important to use herbal medicines with less side effects.

Origanum L. genus have many species both in the world and in Turkey. Origanum onites L. is one of the economically important commercially grown oregano species. Therefore, cultivation and agronomic studies were concentrated on this species. Studies on determination of yield and quality characteristics of other Origanum species are needed. In this study, yield and quality characteristics of O. onites, O. sipyleum, endemic species O.laevigatum and O. husnucan-baseri species were investigated. The trials were conducted as 3 replicates according to the randomized complete block design in 2017 and 2018. The highest plant height (121.60 cm) and the highest branch number (64 pcs plant-1) were obtained from O. sipyleum in the second year. The fresh herb yield values per plant varied from 44.00 to 304.57 g/plant. The highest essential oil rate was obtained from O. husnucan-baseri. Cymene rate (70.69%) was higher in O. sipyleum. The main essential oil components of the Origanum species were cymene (70.69%) for O. Sipyleum; β-caryophyllene (27.76%), -terpinene (25.74%) and myrcene (8.84%) for O. laevigatum; cymene (51.54%), -terpinene (24.73%), carvacrol (6.51%) and thymol (6.20%) for O. husnucan-baseri.

Objective: Origanum minutiflorum essential oil was evaluated for its chemical components, in vitro antioxidant, scolicidal and anticancer activities. Methods: Oil was extracted and its components were identified with spectrometry and flame ionisation gas chromatography. The oil antioxidant activity was evaluated by DPPH radical scavenging and β-Carotene/linoleic acid bleaching assay. Scolicidal effect of the oil against protoscolices of hydatid cysts was evaluated at different concentrations and exposure times. Also, different oil concentrations were testififed for its anticancer activities on breast cancer cell line (MCF-7), human lung cancer cell line (A-549) and human hepatocellular carcinoma cell line (HepG2) Results: Analyses of the O. minutiflorum oil identified 64 components with carvacrol being the predominant compound. The oil showed a weak free radical scavenging capacity (IC50 at 310 ± 4.2 µg/mL) whilst it was moderately active in term of the suppression of linoleic acid oxidation (64.6%). All the tested oil concentrations, however, revealed a significant scolicidal activity on the protoscoleces of hydatid cysts. The anticancer activity of O. minutiflorum oil was found more in HepG2 cells followed by A-549 and MCF-7 cells and this was evidenced by the LC50 values. Conclusions: The present work strongly suggests that O. minutiflorum could serve as a potential source of scolicidal and anticancer agents.

This study reports the development of a set of 20 highly polymorphic genomic SSR markers which can be used for both cultivar identification and genetic diversity studies in several Origanum species, including some of the most popular ones like Greek oregano (Origanum vulgare L. ssp. hirtum), common oregano (O. vulgare L. ssp. vulgare), and sweet marjoram (O. majorana L.). Analysis of the polymorphic information content (PIC) showed an average PIC value of 0.75 with a minimum of 0.41 and a maximum of 0.89, where 17 of the markers showed PIC values above 0.73. Comparative analysis of the genetic diversity of eight natural populations of Greek oregano in Bulgaria showed that six of the genomic SSR markers revealed significantly higher portions of genetic diversity in the populations, compared to 12 EST SSR markers used in our previous study. We also compared the performance of the same six genomic SSR markers with the results for eight SRAP primer combinations, which showed that SRAP markers captured more precisely the genetic structure in natural populations. The developed highly polymorphic genomic SSR markers can be successfully applied to evaluation of the genetic diversity in the genus Origanum, based on the expected and observed heterozygosity in the populations as well as for easy identification of breeding lines and cultivars based on unique SSR fingerprints.

A novel, inexpensive and simple experimental setup for collecting μ-Raman spectra of volatile liquids in very small quantities was developed. It takes advantage of capillary forces to detain minute volatile liquid volumes. Spectra of volatile and even scattering or absorbing media can be measured more effectively. The method is used to facilitate the collection of intensity-consistent Raman spectra from a series of reference compounds present in Origanum essential oils, in order to quantify their constituents by multiple linear regression. Wild grown Origanum plants, collected from five different regions in Greece and taxonomically identified as O. onites, O. vulgare subsp. hirtum and O. vulgare subsp. vulgare, were appropriately distilled to acquire their essential oils. Comparison of the Raman results with those from headspace gas chromatography–mass spectrometry (HS GC-MS) confirmed the successful relative quantification of the most abundant essential oil constituents, highlighting the similarities and differences of the three Origanum taxa examined. Finally, it is demonstrated that directly measuring the leaf peltate glandular hairs yields exploitable results to identify the main components of the essential oil they contain, underlining the potential of in situ (field or industry) measurements utilizing microscope-equipped portable Raman spectrometers.

Essential oils from Monarda fistulosa L., Satureja pilosa Vel., Origanum vulgare subsp. hirtum Ietswaart. (Greek oregano), Micromeria dalmatica Benth., Thymus longedentatus (Degen Urum.) Ronniger, and Artemisa campestris L. were evaluated as inhibitors of seed germination in target plants Lolium perenne L. and Trifolium pratense L. using in vitro assays. The essential oils were applied on the seeds as aqueous solutions at concentrations ranging from 0.5–3.0 µL/mL. Complete inhibition was established at a concentration of 1.5 µL/mL with the most effective essential oils. Oregano oil was evaluated for its inhibitory activity on seed germination under field conditions; the essential oil was applied as an aqueous solution at concentrations of 3, 5, and 10 µL/mL on superabsorbent Terawet. The mass obtained was mixed with the seeds of the target plants and planted in a field. After 1 month, the results were evaluated based on the weight of the aerial parts of the plants from control and experimental areas. At the highest concentration studied, the weight of the plants was 77% lower in the experimental areas than in the controls. The chemical composition of the essential oils was analyzed using gas chromatography–mass spectrometry. The results showed that carvacrol-rich essential oils had a strong inhibitory effect on seed germination. The inclusion of the essential oil on a superabsorbent was a good way to preserve its herbicidal activity under field conditions as this prevented its rapid evaporation.

In this study, chromosome numbers and structures of some Origanum L. taxa growing in Turkey were identified. Using the Image Analysis System, the complements of plant accessions belonging to eight sections, namely Amaracus (Gleditsch) Vogel, Anatolicon Benth., Brevifilamentum Ietsw., Longitubus Ietsw., Chilocalyx (Briq.) Ietsw., Majorana (Miller) Ietsw., Origanum, and Prolaticorolla Ietsw. were determined, by classification with the cytogenetic method. The chromosome number of all taxa except O. sipyleum L. (2n = 28) and O. rotundifolium Boiss. (2n = 28) is 2n = 30. In addition, the hybrids and their parental species have 2n = 30 chromosome numbers. Also, the smallest chromosome length is 0.32 μm in O. sipyleum. The largest chromosome length is 2.02 μm in O. minutiflorum O.Schwarz & P.H.Davis. The smallest total haploid length is 10.08 μm in O. vulgare subsp. hirtum (Link) A.Terracc. and the largest value is 22.00 μm in O. haussknechtii Boiss. The smallest mean length is 0.33 μm in O. vulgare L. subsp. hirtum and O. saccatum P.H.Davis. The largest mean length is 0.74 μm in O. sipyleum L. The chromosome numbers obtained in this study support the speciation of Origanum members via homoploid hybridization. Finally, the somatic chromosome numbers of 10 taxa (including 2 hybrids), chromosome measurements of 22 taxa (including 2 hybrids), and ideograms of 19 taxa (including 2 hybrids) were for the first time performed in this study.

Background: Chronic rhinosinusitis is one of the most common diseases affecting the quality of life of patients. Patients suffer from high costs in the diagnosis and treatment of the disease. Frequent recurrence and failure of therapeutic protocols are among the most important issues in the management of this disease. In view of this, the use of traditional and complementary therapies to promote the treatment of this disease has been increasingly taken into account. Objective: Comparison of the effectiveness of the Persian Medicine Protocol with the conventional therapy in the treatment of chronic rhinosinusitis. Methods: A randomized clinical trial was conducted at Imam Reza Hospital in Mashhad, Iran from July 2016 to March 2017. For patients with chronic rhinosinusitis symptoms, endoscopy of the sinuses was performed by an ENT specialist and in the case of negative endoscopy, paranasal sinus CT scan was requested. A total of 42 patients with chronic rhinosinusitis were randomly assigned to two groups. The first group (classical) received systemic and intranasal cortisone, and the second group (traditional) received a therapeutic Persian medicine protocol including intranasal lavender oil, and Liquorice Marjoram Tea (L. M. tea) for six weeks. The symptoms of the patients were evaluated using the SNOT-22 questionnaire at the beginning of the study and at the sixth week. If no improvement occurs, treatment continued for 12 weeks. Data were analyzed by SPSS version 16, using ANOVA, independent-samples and paired-samples t-test, Wilcoxon signed-rank test, and simple linear regression. Results: In 20 patients in the traditional group, the decrease in SNOT score was observed as 56% after 6 weeks treatment (p=0.001), which is similar to the effect of the first group (classical). Although there was no statically significant difference between the two groups, in clinical terms, the difference in mean systemic symptoms such as confusion with 1.05 (p=0.5) and fatigue with 1.63 (p=0.01) had more improvement in the traditional group, and the difference in mean local symptoms such as nasal congestion with 2.37 (p=0.78) and runny nose with 1.95 (p=0.14) had a more decrease in the classical group. Conclusion: The results of this trial indicate the effectiveness of the Persian Medicine Protocol (including Lavender oil and L.M tea) in the treatment of chronic rhinosinusitis, especially on improving systemic symptoms. http://www.ephysician.ir Page 7018 Nevertheless more clinical studies are necessary to support the acquired results. Trial registration: This trial was registered at the Iranian Center for Clinical Trials (ID: IRCT2015112425217N1). Funding: This research is part of a PhD thesis and is funded by the Vice-Chancellor for Research at Mashhad University of Medical Sciences, Grant No. 931673.

Lipid oxidation is one of the main limiting factors for the quality and acceptability of frankfurkter type of sausages. The antioxidant activity has been measured using a TBA assay. Dried oregano (Origanum vulgare) and thyme (Thymus vulgare) were purchased from a local store and kept in dark until the use. Aqueous extracts were prepared by one-step extraction with 3 g of each pulverized plant. Samples of freshly cooked sausages were evaluated by a 6 member semi-trained panel of laboratory co-workers. Panelists evaluate appearance overall texture, flavour, aroma and overall acceptability on a 6 point hedonic scale. In this work the antimicrobial and antioxidant effect of Thymus vulgare and Origanum vulgare significantly reduced (p

In recent years, Russia has shown the increased interest of consumers to food products enriched with natural bioactive ingredients. The fundamental resource-saving technological scheme of production of fortified sugar confectionery has been developed. The authors justified the choice of raw materials of plant origin: fresh cowberry ( Vaccinium vitisidea ) and cranberry ( Vaccinium oxycoccos L. ) fruits, air-dried oregano shoots ( Origanum vulgare L. ) growing in the Krasnoyarsk region as functional ingredients. The usefulness of the development of functional purpose sugar confectionery from cowberry and cranberry fruits soaked in "Oregano" syrup based on an aqueous extract of oregano shoots has been proven. The change in vitamin C concentration in plant raw materials under the influence of heat treatment has been studied, which helped to justify the optimum thermal conditions for ensuring the preservation of vitamin C. A distinctive feature of the developed resource-saving technological scheme is pre-saturation of fruit and berry raw material with the origanum complex of biologically active substances and integrated use of original plant ingredients. The research of microbiological, toxicological, physical and chemical indices of the enriched sugar confectionary - «Cranberry in chocolate», «Cowberry in chocolate», proved the sanitary and hygienic safety and functional qualities of the products.

El cultivo de orégano se desarrolla en regiones de clima semiárido en donde existe un balance hídrico negativo, siendo necesario contar con un sistema de irrigación que permita cubrir las necesidades de agua. La zona de 25 de Mayo, La Pampa, alimentada por el Río Colorado, posee un sistema de riego que la convierte en un área con alto potencial para dicha producción. El objetivo de este trabajo fue caracterizar el comportamiento productivo de cuatro ecotipos de orégano (Criollo, Mendocino, Cordobés y Compacto) en la zona bajo riego de 25 de Mayo. Para ello, se determinó el porcentaje de materia seca de flor y hoja, peso fresco y seco de parte aérea de las muestras de cada ecotipo. Los resultados mostraron que no existen diferencias significativas en relación al rendimiento (p=0.05). Sin embargo, productivamente se observan diferencias de importancia, siendo los ecotipos Criollo y Cordobés los de mejor comportamiento. Los rendimientos obtenidos fueron mayores al promedio de las regiones productoras por excelencia, tales como Mendoza y Córdoba, por lo que el área en estudio se presenta como una opción prometedora para la producción de orégano. DOI: http://dx.doi.org/10.19137/semiarida.2016(01).35-42

In this work, proton NMR relaxometry was used to measure the behavior of spin-lattice relaxation time with T1H as the time constant, and also of spin-spin relaxation time with the time constant T2H. These relaxometry parameters were determined to better understand the changes in the main structures present in commercial and in nature forms of origanum. The T1H relaxation data showed that the structures which had higher molecular mass were more sensitive to degradation with increased temperature treatment. According to the values of the T2H parameter, up to 150 degrees no significant change in the mobility and organization of water was observed. These data infer that the ideal cooking temperature and tea preparation mode for this herb should be around 100 degrees for the sample not to lose its characteristics. Also, it is not advisable to cook this herb at higher than 150 degrees but better to consume it at room temperature, especially give commercial herb has already been dehydrated.

Background: Brucellosis, a zoonosis caused by four species of brucella, has a high morbidity. The major cause of brucellosis worldwide is brucella melitensis. Medicinal plants are considered as new antibacterial sources that could replace conventional antibiotics in the treatment of antibiotic-resistant bacteria. The aim of this study was to evaluate the efficacy of some native plants, alone and in combination with some antibiotics, in the treatment of brucellosis.Methods: The present experimental in vitro study was carried out to evaluate the anti-brucella activities of essential oils of Rosmarinus officinalis L., Origanum syriacum, Thymus syriacus, Salvia palaestina Benth, Mentha piperia, and Lavandula stoechas L., alone and in combination with some antibiotics. The activity against 16 tetracycline-resistant B. melitensis isolates was determined by disc diffusion method incorporating a concentration of 5%. Antibiotic discs were also used as a control. Microdilution brucella broth susceptibility assay was used in order to determine the MICs of essential oils and five antibiotics.Results: Among all the herbs evaluated, only the essential oils of O. syriacum and T. syriacus plants demonstrated most effective anti-brucella activity, and were then chosen for MIC study. The minimal inhibitory concentrations (MIC50) of essential oils of O. syriacum and T. syriacus against tetracycline-resistant B. melitensis were 3.125 µl/ml and 6.25 µl/ml, respectively. Conclusion: Among the essential oils studied, those of O. syriacum and T. syriacus were most effective. Since a combination of levofloxacin and Thymus syriacus essential oil increased the efficacy of this antibiotic, O. syriacum and T. syriacus are recommended to be used as bactericidal agents against B. melitensis.

Oregano is a common culinary herb used as spice in different parts of the world. Origanum is a genus of Lamiaceae family with many species. Two species Origanum majorana L. and Origanum vulgare L. have therapeutic properties. Besides using as a spice in food, the herb has been used in treatment of some conditions including colds, respiratory allergies, gastrointestinal disorders, diabetes mellitus, wound healing and as a tranquilizer, in alternative medicine for centuries. Until now, numerous reports on its biological and pharmacological properties and also analysis of its extracts or oils have published. According to reliable scientific studies, Origanum spp. have a strong antioxidant and antimicrobial effects against common human and foodborne pathogens. Based on frequent biochemical analysis of extracts and essences of the herb, phenolic compounds especially phenolic acids and flavenoids are probable responsible agents. These days, investigations are focused on antidiabetic, antihypertensive, anti-inflammatory, cytotoxicity and antimutagenic action of genus Origanum, besides the antioxidant and antibacterial activities.

In the present study, we have evaluated the in vitro antibacterial activity of essential oils from Origanum vulgare, Thymus vulgaris, Lavandula angustifolia, Mentha piperita, and Melaleuca alternifolia against 32 erythromycin-resistant [MIC ≥1 µg/mL; inducible, constitutive, and efflux-mediated resistance phenotype; erm(TR), erm(B), and mef(A) genes] and cell-invasive Group A streptococci (GAS) isolated from children with pharyngotonsillitis in Italy. Over the past decades erythromycin resistance in GAS has emerged in several countries; strains combining erythromycin resistance and cell invasiveness may escape β-lactams because of intracellular location and macrolides because of resistance, resulting in difficulty of eradication and recurrent pharyngitis. Thyme and origanum essential oils demonstrated the highest antimicrobial activity with MICs ranging from 256 to 512 µg/mL. The phenolic monoterpene carvacrol [2-Methyl-5-(1-methylethyl) phenol] is a major component of the essential oils of Origanum and Thymus plants. MICs of carvacrol ranged from 64 to 256 µg/mL. In the live/dead assay several dead cells were detected as early as 1 h after incubation with carvacrol at the MIC. In single-step resistance selection studies no resistant mutants were obtained. A synergistic action of carvacrol and erythromycin was detected by the checkerboard assay and calculation of the FIC Index. A 2- to 2048-fold reduction of the erythromycin MIC was documented in checkerboard assays. Synergy (FIC Index ≤0.5) was found in 21/32 strains and was highly significant (p