Abatsract Pseudomonas aeruginosa is an important nosocomial pathogen and its clinical importance is mainly related to nosocomial infections. Increased rates of bacterial resistance in recent years has led WHO to publish a global priority list to guide research and discovery of new antibiotics, where P. aeruginosa is among the group of bacteria for which there is a critical level of priority for new drugs to be discovered. In this context, isoeugenol appears as an interesting alternative and the objective of this study was to investigate its action against P. aeruginosa. Isoeugenol presented significant antibacterial activity, with minimum inhibitory concentration (MIC) of 64µg/mL and minimum bactericidal concentration (MBC) of 128µg/mL, and was considered bactericidal against this species. Molecular docking revealed interactions that suggest that isoeugenol may bind to the enzyme Penicillin-Binding Protein 3 and interfere with the bacterial cell wall synthesis process. This study reinforces the antibacterial potential of this compound and emphasizes that more studies are needed in order to better investigate its mechanism of antibacterial action.

Abstract A bioassay-guided fractionation of two samples of Brazilian red propolis (from Igarassu, PE, Brazil, hereinafter propolis 1 and 2) was conducted in order to determine the components responsible for its antimicrobial activity, especially against Candida spp. Samples of both the crude powdered resin and the crude ethanolic extract of propolis from both locations inhibited the growth of all 12 tested Candida strains, with a minimum inhibitory concentration of 256 µg/mL. The hexane, acetate and methanol fractions of propolis 1 also inhibited all strains with minimum inhibitory concentration values ranging from 128 to 512 µg/mL for the six bacteria tested and from 32 to 1024 µg/mL for the yeasts. Similarly, hexane and acetate fractions of propolis sample 2 inhibited all microorganisms tested, with minimum inhibitory concentration values of 512 µg/mL for bacteria and 32 µg/mL for yeasts. The extracts were analyzed by HPLC and their phenolic profile allowed us to identify and quantitate one phenolic acid and seven flavonoids in the crude ethanolic extract. Formononetin and pinocembrin were the major constituents amongst the identified compounds. Formononetin was detected in all extracts and fractions tested, except for the methanolic fraction of sample 2. The isolated isoflavone formononetin inhibited the growth of all the microorganisms tested, with a minimum inhibitory concentration of 200 µg/mL for the six bacteria strains tested and 25 µg/mL for the six yeasts. Formononetin also exhibited fungicidal activity against five of the six yeasts tested. Taken together our results demonstrate that the isoflavone formononetin is implicated in the reported antimicrobial activity of red propolis.

resumo Sidastrum micranthum (A. St.-Hil.) Fryxell, pertencente à família Malvaceae, é conhecida no Brasil como "malva preta". A espécie é popularmente usada contra bronquite, tosse e asma, mostrando a relevância de conhecer melhor sua composição química. O estudo fitoquímico do extrato hexânico da espécie, utilizando técnicas cromatográficas, conduziu ao isolamento de seis compostos: o triterpeno isoarborinol, mistura de sitosterol e estigmasterol, sitosterol-3-O-β-D-glicopiranosídeo, feofitina a e de 132-hidroxi-(132-S)-feofitina a. A identificação estrutural destes compostos foi realizada com base em métodos espectroscópicos, tais como IV, RMN 1D e 2D (HOMOCOSY, HMQC, HMBC e NOESY). As substâncias isoladas de Sidastrum micranthum foram avaliadas quanto às suas atividades antimicrobianas in vitro, contra vinte cepas fúngicas e bacterianas. A feofitina a mostrou ação antimicrobiana contra todos os microrganismos testados.

abstract Sidastrum micranthum (A. St.-Hil.) Fryxell, a member of the Malvaceae family, is called malva preta in Brazil. As this species is commonly used to treat bronchitis, cough, and asthma, better knowledge of its chemical compounds is important. The phytochemical study of its hexane extract, using chromatographic techniques, led to isolation of six compounds: the triterpene isoarborinol, a mixture of sitosterol and stigmasterol, sitosterol-3-O-β-D-glucopyranoside, pheophytin a, and 132-hydroxy-(132-S)-pheophytin a. Structural identification of these compounds was carried out using spectroscopic methods such as IR and 1D and 2D NMR (HOMOCOSY, HMQC, HMBC, and NOESY). Compounds isolated from S. micranthum were screened for their in vitro antifungal and antibacterial activity against twenty fungal and bacterial standard strains. Pheophytin a exhibited antimicrobial action against all microorganisms tested.

Three flavanones, two chalcones and one dihydrochalcone were isolated from the branches of Piper glandulosissimum. All isolated compounds were characterized based on IR, UV, 1H and 13C NMR, including 2D NMR analyses (HMQC, HMBC, COSY and NOESY) and comparison with the literature. The compound 7-hydroxy-5,8-dimethoxyflavanone displayed antimicrobial activity against Staphylococcus aureus, S. epidermidis, Trichophyton mentagrophytes and Microsporum canis.

The purpose of this study was to identify the anti-Candida activity and chemical composition of the essential oil (EO) of Cinnamomum zeylanicum (cinnamon). For this, tests were conducted to determine the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) and the action of C. zeylanicum EO on fungal cell wall of Candida albicans, C. tropicalis and C. krusei strains. The composition of the was analysed by gas chromatography with mass spectrometry. Significant antifungal activity of the EO was observed on the strains tested, with 87.5% and 62.5% of them sensitive, respectively at a MIC of 312.5 µg/mL and MFC of 2500 µg/mL. In the presence of sorbitol, the MIC was 625 µg/mL against all the strains, showing a possible action of the EO on fungal cell wall. Eugenol (73.27%) and trans-β-caryophyllene (5.38%) were found in higher concentrations. The results indicated anti-Candida activity of the EO analyzed and suggested that it occurred due to the action on fungal cell wall.

Introduction: considering the emergence of resistant species of albicans and non-albicans Candida to agents therapeutically available as a result of the increased number of immunocompromised population and of the increasingly frequent use of prophylaxis and empirical treatment with antifungals, it's verified that there is a clear and emerging need to introduce new antimicrobials agents in the therapeutic arsenal. The purpose of this study was to evaluate the antifungal activity of essential oil of Cinnamomum zeylanicum Blume alone and combined with Nystatin on strains of C. tropicalis and C. krusei. Methods: this was an experimental research in laboratory. It was determined the Minimum Inhibitory Concentration, using the microdilution method, as well as the Fractional Inhibitory Concentration to determine the possible synergistic effects of the association. Strains of C. tropicalis ATCC 40147 and C. krusei ATCC 40042 were used in the tests. When assessed separately, C. zeylanicum essential oil and Nystatin presented Minimum Inhibitory Concentration of 312,5 µg/mL and 64 µg/mL, respectively, on both tested strains. Results: When combined, were found Minimum Inhibitory Concentration of 39 µg/mL and 32 µg/mL for the essential oil and for Nystatin, respectively. The Fractional Inhibitory Concentration value was 0,6024 for both tested strains, indicating additivity of the inhibitory effect on fungal growth. Conclusions: the results indicate that C. zeylanicum essential oil has antifungal activity against the strains of non-albicans Candida evaluated and that its association with Nystatin potentiates this effect.

Introducción: es necesaria la introducción de nuevos agentes antimicrobianos por el surgimiento de especies de Candida albicans y no albicans resistentes a los agentes terapéuticos disponibles .El objetivo del estudio fue evaluar la actividad antifúngica del aceite esencial de Cinnamomum zeylanicum Blume aislado y asociado con nistatina sobre cepas Candida tropicalis y Candida krusei. Métodos: se realizó una investigación experimental de laboratorio. La concentración mínima inhibitoria fue determinada utilizando el método de microdilución, y la concentración inhibitoria fraccionada se usó para determinar los posibles efectos sinérgicos de la asociación. Para las pruebas fueron utilizadas las cepas de C. tropicalis ATCC 40147 y C. krusei ATCC 40042. Se usaron el aceite esencial de C. zeylanicum y nistatina. Cuando fueron evaluados por separado presentaron la concentración mínima inhibitoria de 312,5 µg/mL y de 64 µg/mL, respectivamente, sobre ambas cepas ensayadas. Resultados: una vez asociados, la concentración mínima inhibitoria fue de 39 µg/mL para el aceite esencial y de 32 µg/mL para la nistatina. El valor de la concentración inhibitoria fraccionada para ambas cepas probadas fue de 0,6024, lo que indica adicción del efecto inhibidor sobre el crecimiento de hongos. Conclusiones: los resultados indican que el aceite esencial de C. zeylanicum tiene actividad antifúngica frente a las cepas de Candida no albicans y que la asociación del mismo con la nistatina promueve la potenciación de este efecto.

FUNDAMENTOS: Pitiríase versicolor é uma micose causada pela Malassezia spp., e que apresenta frequentes recidivas. OBJETIVOS: Este trabalho objetivou realizar estudos clínicos de fase I e II, para essa patologia, com óleo essencial de Cymbopogon citratus. MÉTODOS: Na fase I, participaram vinte voluntários para averiguar a segurança das formulações. Na fase II, 47 voluntários receberam as formulações do óleo essencial a 1,25 μL/mL, as quais deveriam ser utilizadas por quarenta dias, sendo o xampu três vezes por semana e o creme duas vezes ao dia. Um grupo controle na fase II, constituído por 29 voluntários recebeu as mesmas formulações, com cetoconazol a 2%. RESULTADOS: Verificada a segurança das formulações com a finalização da fase I, onde nenhuma reação adversa significativa foi observada nos indivíduos sadios, conduziu-se a fase II. Nesta segunda fase, 30 (63,83%) voluntários utilizando óleo essencial e 18 (62,07%) cetoconazol permaneceram até o final do estudo. Observaram-se nos pacientes com pitiríase versicolor predomínio de lesões na forma disseminada e M. sympodialis foi o agente predominante identificado em cultura. Após 40 dias de tratamento, obteve-se um percentual de cura micológica de 60% (p < 0,05) para o grupo tratado com óleo essencial de C. citratus e superior a 80% (p < 0,05) para o grupo tratado com cetoconazol. CONCLUSÕES: Apesar da segurança e efeito antifúngico observados após aplicação das formulações contendo óleo essencial de C. citratus, outros estudos com maior número de portadores de pitiríase versicolor precisam ser realizados para confirmar o real potencial destas formulações.

BACKGROUND: Pityriasis versicolor is a fungal infection caused by Malassezia spp. that has frequent relapses. OBJECTIVES: The main objective of this research was to perform phase I and II clinical studies, using formulations containing essential oil of Cymbopogon citratus in patients with pityriasis versicolor. METHODS: Phase I study included twenty volunteers to ascertain the safety of the formulations. In phase II, 47 volunteers randomly received essential oil formulations at 1.25 μL/mL concentration, for forty days. The shampoo should be applied three times a week and the cream twice a day. A control group in phase II, consisting of 29 volunteers, received the same formulations but with 2% ketoconazole as the active ingredient. RESULTS: No significant adverse events were observed in volunteers during Phase I. In Phase II, 30 (63.83%) volunteers using essential oil and 18 (62.07%) using ketoconazole remained until the end of the study. We observed a predominance of lesions in disseminated form, with M. sympodialis detected as the predominant agent identified in cultures. After 40 days of treatment, the rate of mycological cure was 60% (p <0.05) for the group treated with essential oil of C. citratus and over 80% (p <0.05) for the group treated with ketoconazole formulations. CONCLUSIONS: Notwithstanding the safety and antifungal effects observed in this study after application of formulations containing the essential oil of C. citratus, further studies with larger populations should be performed to confirm the actual potential of these formulations in the treatment of patients with Pityriasis versicolor.

A utilização de produtos naturais na odontologia tem se mostrado como uma fonte alternativa no combate às patologias orais, incluindo as infecções fúngicas, causadas, geralmente, por Candida spp. Avaliar a ação antifúngica de tinturas de própolis Apis milifera e romã Punica granatum sobre Candida albicans (ATCC 76618), Candida krusei (ATCC 6538) e Candida tropicalis (ATCC 13803). A ação antifúngica das tinturas foi avaliada pelo método da Concentração Inibitória Mínima em meio de cultura sólido Ágar Saburaud Dextrose (Difco®). Foram confeccionados poços, com 6 mm de diâmetro, destinados a inserção de 50 µL das tinturas. Foram avaliadas seis concentrações seriadas das tinturas, sendo a concentração inicial para a tintura de própolis 200 mg/mL e 300 mg/mL a concentração inicial para a tintura de romã. Posteriormente, as placas de Petri foram incubadas em estufa bacteriológica por 48 h a 37 ºC. A análise dos dados para a Concentração Inibitória Mínima foi feita através da mensuração dos halos de inibição, sendo considerados quando iguais ou superiores a 10 mm de diâmetro. Para a tintura de romã observou-se que as Concentração Inibitória Mínima sobre Candida albicans, Candida krusei e Candida tropicalis foram 9,37 mg/mL, 9,37 mg/mL e 18,75 mg/mL, respectivamente. Em relação à tintura da própolis, constatou-se que apenas em sua forma pura apresentou ação antifúngica sobre Candida krusei e Candida tropicalis, entretanto a mesma ação não foi observada sobre Candida albicans. As tinturas avaliadas apresentam ação antifúngica sobre as cepas avaliadas, exceto a tintura da própolis sobre Candida albicans.

The use of natural products in Dentistry has been shown as an alternative source against oral diseases, including fungi infections, generally caused by Candida spp. The aim was to evaluate the antifungal action of tinctures from propolis (Apis milifera) and from pomegranate (Punica granatum) on Candida albicans (ATCC 76618), Candida krusei (ATCC 6538) and Candida tropicalis (ATCC 13803). The antifungal activity of tinctures was evaluated by Minimum Inhibitory Concentration method on Saburaud Dextrose Agar (Difco®). Six wells were confectioned, with 6 mm of diameter, to the insertion of 50 µL of tinctures. Six serial concentrations were evaluated, been 200 mg/mL the initial concentration for tincture from propolis and 300 mg/mL the initial concentration for tincture from pomegranate. Later, the Petri plates were incubated in bacteriological incubator for 48 h on 37 ºC. Data analysis for Minimum Inhibitory Concentration was conducted by measurement of inhibition zones, been considered inhibited when equal or bigger than 10 mm of diameter. For tincture from pomegranate, was verified that the Minimum Inhibitory Concentration on Candida albicans, Candida krusei and Candida tropicalis were 9.37 mg/mL, 9.37 mg/mL and 18.75 mg/mL, respectively. For tinctures from propolis, the antifungal action was verified only in pure concentration on Candida krusei and Candida tropicalis, but it was not observed on Candida albicans. The tinctures from pomegranate and propolis had antifungal activity on evaluated strains, except for tincture from propolis on Candida albicans.

Se ha demostrado que el uso de productos naturales en Estomatología es una fuente alternativa contra las enfermedades orales, incluyendo las infecciones micóticas, generalmente causadas por Candida spp. El objetivo de este trabajo fue evaluar la acción antimicótica de las tinturas a partir del propóleo (Apis milifera) y a partir de pomegranate (Punica granatum) sobre Candida albicans (ATCC 76618), Candida krusei (ATCC 6538) y Candida tropicalis (TCC 13803). La actividad antimicótica de las tinturas fue evaluada por el método Minimum Inhibitory Concentration en Aagar Dextrosa Saburaud (Difco®). Se crearon 6 orificios con un diámetro de 6 mm para la inserción de 50 µL de tinturas. Se evaluaron 6 concentraciones seriadas donde la concentración inicial para las tinturas a partir de propóleo fue de 200 mg/mL y de 300 mg/mL como concentración inicial para la tintura a partir de pomegranate. Posteriormente, los discos de Petri fueron incubados durante 48 h a 37ºC. El análisis de los datos para Minimum Inhibitory Concentration fue realizado midiendo las zonas de inhibición, se consideró inhibición cuando es igual o mayor de 10 mm de diámetro. En el caso de la tintura de pomegranate, se comprobó que la Minimum Inhibitory Concentration en Candida albicans, Candida krusei y Candida tropicalis fueron de 9,37 mg/mL, 9,37 mg/mL y 18,75 mg/mL respectivamente. Para las tinturas a base de propóleo, la acción antimicótica fue verificada solo en la concentración pura sobre Candida krusei y Candida tropicalis, pero no fue observada en Candida albicans. Las tinturas a base de pomegranate y propóleo tuvieron actividad antimicótica sobre las cepas evaluadas, excepto en el caso de la tintura a base de propóleo sobre Candida albicans.

The phytochemical investigation of L. macrophylla Benth led to the isolation of a new flavanol named licanol: (-)-4'-O-methyl-epigallocatechin-3'-O-α-L-rhamnoside, along with nine known compounds, identified as: (-)-4'-O-methyl-epigallocatechin, pheophytin A, 13²-hydroxy-(13²-S)-pheophytin A, pheophytin B, sitosterol, stigmasterol, sitosterol-β-O-glucoside, betulinic alcohol and oleanolic acid. The structures were established based on IR, HR-ESI-MS, and NMR spectrometric data analysis with the aid of 2D techniques. The methanolic extracts of leaves and stem bark as well as the compounds licanol, 13²-hidroxi-(13²-S)-feofitina A, and betulinic alcohol demonstrated antimicrobial activity against several bacterial strains.

Candida albicans is an opportunistic yeast and a member of the normal human flora that commonly causes infections in patients with any type of deficiency of the immune system. The essential oils have been tested for antimycotic activity and pose much potential as antifungal agents. This work investigated the activity of the essential oil of Cymbopogon winterianus against C. albicans by MIC, MFC and time-kill methods. The essential oil (EO) was obtained by hydrodistillation using a Clevenger-type apparatus. It was tested fifteen strains of C. albicans. The MIC was determined by the microdilution method and the MFC was determined when an aliquot of the broth microdilution was cultivated in SDA medium. The phytochemical analysis of EO showed presence of citronellal (23,59%), geraniol (18,81%) and citronellol (11,74%). The EO showed antifungal activity, and the concentrations 625 µg/mL and 1250 µg/mL inhibited the growth of all strains tested and it was fungicidal, respectively. The antimicrobial activity of various concentrations of EO was analyzed over time, it was found concentration-dependent antifungal activity, whose behavior was similar to amphotericin B and nystatin.

Trichophyton rubrum is one of the most common fungi causer of dermatophytosis, mycosis that affect humans and animals around the world. Researches aiming new products with antifungal activity become necessary to overcome difficulties on treatment of these infections. Accordingly, this study aimed to investigate the antifungal activity of essential oil from Cymbopogon winterianus against the dermatophyte T. rubrum. The antifungal screening was performed by solid medium diffusion method with 16 T. rubrum strains, minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were determined using the microdilution method. The effects on mycelial dry weight and morphology were also observed. Screening showed essential oil in natura inhibited all the tested strains, with inhibition zones between 24-28 mm diameter. MIC50 and MIC90 values of the essential oil were 312 µg/mL for nearly all the essayed strains (93.75 %) while the MFC50 and MFC90 values were about eight times higher than MIC for all tested strains. All tested essential oil concentrations managed to inhibit strongly the mycelium development. Main morphological changes on the fungal strains observed under light microscopy, which were provided by the essential oil include loss of conidiation, alterations concerning form and pigmentation of hyphae. In the oil presence, colonies showed folds, cream color and slightly darker than the control, pigment production was absent on the reverse and with evident folds. It is concluded that C. winterianus essential oil showed activity against T. rubrum. Therefore, it could be known as potential antifungal compound especially for protection against dermatophytosis.

Trichophyton mentagrophytes é um fungo causador de dermatofitoses, afetando humanos em todo o mundo. Isto direciona a busca de produtos para o tratamento destas infecções. Assim, este estudo teve por objetivo investigar a atividade antifúngica do óleo essencial de Cymbopogon winterianus contra T. mentagrophytes. Os ensaios antifúngicos foram constituídos do screening antifúngico, da determinação CIM e CFM, da análise dos efeitos do óleo essencial no crescimento micelial, na germinação dos esporos, na viabilidade fúngica, na morfogênese, na parede celular (ensaio com sorbitol) e na membrana celular (ensaio de lise celular) de T. mentagrophytes. No screening, o óleo inibiu todas as cepas, com zonas de inibição de crescimento de 24-28 mm de diâmetro. A CIM foi de 312 μg/mL e a CFM foi de 2500 μg/mL para quase todas as cepas testadas. O óleo essencial inibiu o desenvolvimento micelial, a germinação dos esporos e a viabilidade fúngica. Houve alterações morfológicas no agrupamento dos conídios, na forma e pigmentação das hifas. A ação antifúngica do produto não envolve a parede celular e parece estar envolvida com a membrana celular fúngica. Pode-se concluir que o óleo essencial de C. winterianus se apresenta como um potencial produto antifúngico, especialmente para o tratamento das dermatofitoses.

Trichophyton mentagrophytes is a fungus causative agent of dermatophytosis, affecting humans worldwide. This has driven the search for products for the treatment of these infections. Accordingly, the aim of this study was to investigate the antifungal activity of the Cymbopogon winterianus essential oil against T. mentagrophytes. The antifungal tests consisted of antifungal screening, determination of MIC and MFC, analysis of the essential oil's effects on mycelial growth, germination of fungal spores, fungal viability, morphogenesis, cell wall (test with sorbitol) and cell membrane (cell leakage test) of T. mentagrophytes. Upon screening, the oil inhibited all strains, with zones of growth inhibition of 24-28 mm in diameter. The MIC was 312 μg/mL and CFM was 2500 μg/mL for almost all the strains tested. There were morphological changes in the conidia group, form and pigmentation of hyphae. The antifungal action of the product does not involve the cell wall and its action may involve the fungal plasma membrane. It is concluded that C. winterianus essential oil constitutes a potential antifungal product, especially for the treatment of dermatophytosis.

Cinnamomum zeylanicum Blume, Lauraceae, é uma espécie vegetal reconhecida, a longo tempo, como possuidora de muitas propriedades biológicas. Este estudo objetivou identificar os constituintes do óleo essencial das folhas de C. zeylanicum, utilizando CG-EM, e avaliar seu efeito inibitório sobre Salmonella enterica, Escherichia coli, Staphylococcus aureus e Pseudomonas aeruginosa através da determinação da CIM e CBM, bem como através da análise do tempo de morte bacteriana. Eugenol (73,27%) foi o composto mais prevalente no óleo essencial, seguido por trans-β-cariofileno (5,38%), linalol (3,31%) e álcool acetato cinâmico (2,53%). Os resultados mostraram uma interessante atividade antibacteriana do óleo essencial com CIM, variando de 1,25 a 10 µL.mL-1. Os valores de CBM oscilaram entre 20 e 80 µL.mL-1. O óleo essencial na concentração de 10 e 40 µL.mL-1 causou uma rápida e constante diminuição (2 a 5 ciclos logarítmicos) na contagem de células viáveis de todas as cepas ensaiadas ao longo de 24 horas. O óleo essencial na concentração de 40 µL.mL-1 causou uma total eliminação do inóculo inicial de S. aureus depois de 2 horas. Estes resultados mostram a possibilidade do uso do óleo essencial extraído das folhas de C. zeylanicum como uma fonte alternativa de compostos antimicrobianos para aplicação em sistemas de conservação de alimentos.

Cinnamomum zeylanicum Blume, Lauraceae, has long been known for having many biological properties. This study aimed to identify the constituents of the essential oil from C. zeylanicum leaves using GC-MS and to assess its inhibitory effect on Salmonella enterica, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa based on MIC and MBC determination and kill-time study. Eugenol (73.27%) was the most prevalent compound in the essential oil followed by trans-β-cariophyllene (5.38%), linalool (3.31%), and alcohol cinamic acetate (2.53%). The results showed an interesting antibacterial activity of the oil with MIC ranging from 1.25 to 10 µL.mL-1. MBC values were in the range of 20 - 80 µL.mL-1. A concentration of 10 and 40 µL.mL-1 of the essential oil caused a fast and steady decrease in viable cell count (2 to 5 log cycles) of all assayed strains along 24 hours. A concentration of 40 µL.mL-1 of the oil provided a total elimination of the initial inocula of S. aureus after 2 hours. These results show the possibility of regarding the essential oil from C. zeylanicum leaves as alternative sources of antimicrobial compounds to be applied in food conservation systems.

O objetivo deste estudo foi observar a eficácia do óleo essencial de O. vulgare L. e O. majorana L. na inibição do crescimento e sobrevivência de cepas de fungos potencialmente patogênicas, bem como avaliar os possíveis mecanismos envolvidos no estabelecimento da propriedade antifúngica dos óleos essenciais testados através do ensaio de estabilidade osmótica e morfogênese. As cepas fúngicas utilizadas neste estudo foram Candida albicans ATCC 7645, C. tropicalis LM-14, C. krusei LM-09, Cryptococcus neoformans FGF-5, Aspergillus flavus LM-02, A. fumigatus IPP-21, T. rubrum ATCC 28184, T. mentagrophytes LM-64, Microsporum gypseum ATCC 184, M. canis LM-36 e Cladosporium herbarium ATCC 26362. O óleo essencial de O. vulgare apresentou valor de CIM de 80 µL/mL, enquanto o óleo essencial de O. majorana apresentou valor de CIM de 160 µL/mL. C. krusei LM-09 apresentou-se como a única cepa resistente a todas as concentrações ensaiadas de ambos os óleos essenciais. Os óleos essenciais testados quando ensaiadas em seu valor de CIM causaram um efeito fungicida contra C. albicans ATCC 7645 após 4 h de exposição. O óleo essencial de O. vulgare na concentração de 80 µL/mL exibiu uma total inibição do crescimento micelial radial de T. rubrum ATCC 28184 e M. canis LM-36 ao longo de 14 dias. As cepas fúngicas ensaiadas quando tratadas com sorbitol (agente osmo-protetor) foram capazes de crescer em meio adicionado de mais altas concentrações dos óleos essenciais quando comparados ao meio não adicionado de sorbitol, sugerindo especificidade destes produtos a parede celular como alvo na célula fúngica. As principais alterações causadas pelo óleo essencial de O. vulgare sobre a morfologia de A. flavus LM-02 foram diminuída conidiação, perda de citoplasma, perda de pigmentação e ruptura da estrutura celular indicando degeneração da parede celular fúngica. Estes resultados sugerem que óleos essenciais de espécies de Origanum poderiam ser considerados como potenciais antifúngicos para o controle de fungos patógenos e ocorrência de micoses.

This study aimed to assess the efficacy of O. vulgare L. and O. majorana L. essential oil in inhibiting the growth and survival of potentially pathogenic fungal strains and also sought to evaluate the possible mechanisms involved in the establishment of the antifungal property of the tested essential oils through assays of osmotic stability and morphogenesis. Test strains included in this study were Candida albicans ATCC 7645, C. tropicalis LM-14, C. krusei LM-09, Cryptococcus neoformans FGF-5, Aspergillus flavus LM-02, A. fumigatus IPP-21, T. rubrum ATCC 28184, T. mentagrophytes LM-64, Microsporum gypseum ATCC 184, M. canis LM-36 and Cladosporium herbarium ATCC 26362. O. vulgare essential oil presented a MIC value of 80 µL/mL, while for O. majorana this was 160 µL/mL. C. krusei LM-09 was the only strain resistant to all assayed concentrations of both essential oils. O. vulgare and O. majorana essential oil at their MIC values provided a cidal effect against C. albicans ATCC 7645 after 4 h of exposure. O. vulgare essential oil at 80 µL/mL exhibited 100 % inhibition of the radial mycelia growth of T. rubrum ATCC 28184 and M. canis LM-36 for 14 days. Assayed fungus strain protected by sorbitol (osmo-protectant agent) grew in media containing higher concentrations of O. vulgare and O. majorana essential oil in comparison to media without sorbitol, suggesting some specificity of these essential oils for targeting cell wall in the fungi cell. Main morphological changes observed under light microscopy provided by the essential oil of O. vulgare in A. flavus LM-02 were decreased conidiation, leakage of cytoplasm, loss of pigmentation and disrupted cell structure indicating fungal wall degeneration. These results suggest that essential oils from Origanum could be regarded as a potential antifungal compound for controlling the growth of pathogen fungi and the occurrence of mycoses.