Igara Oliveira Lima

Atividade antifúngica de óleos essenciais sobre espécies de Candida

Candidiasis occurs as a superficial or profound fungal infection caused by yeasts belonging to the Candida genus. This infectious has been considered the main mycotic infection in the nosocomial environment. The aim of this study was to determine the minimum inhibitory concentration - MIC of Cinnamomum zeylanicum Blume, Citrus limon Risso, Eucalyptus citriodora HK, Eugenia uniflora L., Peumus boldus Benth and Rosmarinus officinialis L. essential oils against Candida albicans, C. guilliermondii, C. krusei, C. parapsilosis, C. stellatoidea e C. tropicalis strains. The antifungal activity assays were carried out by solid medium diffusion technique. C. zeylanicum and P. boldus essential oils showed the most prominent results which inhibited the growth of 58% of the assayed yeasts strains and presented MIC of 4%.

Estudo da interferência de óleos essenciais sobre a atividade de alguns antibióticos usados na clínica

The aim of this study was to evaluate the interference of essential oils from Lippia sidoides Cham, Plectranthus amboinicus Lour Spr., Conyza bonariensis L. and Eucalyptus citriodora Hook on the antibacterial effect of clinically used antibiotics. The assays were carried out with ampicillin (10 µg/mL), cephalotin (30 µg/mL), chloraphenicol (30 µg/mL), gentamicin (10 µg/mL) and tetracyclin (30 µg/mL) isolated and associated with essential oils (4% v/v) by the solid medium diffusion procedure using filter paper discs. The results showed interference of some essential oils on the antibacterial activity of the assayed antibiotics. It was observed the development of growth inhibition halo with different diameters when the antibiotics were applied alone and associated with essential oils. Synergic or antagonic behavior was more prominent in interactions with S. aureus and S. epidermidis strains. On the other hand, it was observed a smaller interference of essential oils on the effect of the antibiotics against Gram negative strains, mainly P. aeruginosa. These results show that the use of plants by-products could some times interfere on the effectiveness of antibiotics used clinically.

Review of the plants with anti-inflammatory activity studied in Brazil

The inflammatory reaction is a response of the organism against an injury and it involves the action of complex events and mediators through of the blood vessels. The present work is a literature survey of the extracts of plants with anti-inflammatory activity studied in Brazil. The review refers to 75 plants with their families, parts used, type of extract used, bioassay models and their activity.

Antifungal Activity of Thymus vulgaris L. Essential Oil and Its Constituent Phytochemicals against Rhizopus oryzae: Interaction with Ergosterol

Mucormycoses are emerging infections that have high rates of morbidity and mortality. They show high resistance to antifungal agents, and there is a limited therapeutic arsenal currently available, therefore, there is a great need to give priority to testing therapeutic agents for the treatment of mucormycosis. Along this line, the use of essential oils and phytoconstituents has been emphasized as a new therapeutic approach. The objective of this work was to investigate the antifungal activity of the essential oil (EO) of Thymus vulgaris, and its constituents thymol and p-cymene against Rhizopus oryzae, through microbiological screening, determination of minimal inhibitory concentration (MICs) and minimal fungicidal concentration (MFCs), effects on mycelial growth and germination of sporangiospores and interaction with ergosterol. The MIC of EO and thymol varied 128–512 µg/mL, but the MFC of EO and thymol varied 512–1024 µg/mL and 128–1024 µg/mL, respectively. The results also showed that EO and thymol significantly inhibited mycelial development and germination of sporangiospores. Investigation of the mechanism of antifungal action showed that EO and thymol interact with ergosterol. These data indicate that EO of T. vulgaris and thymol possess strong antifungal activity, which can be related to their interaction with ergosterol, supporting the possible use of these products in the treatment of mucormycosis.

Interference of Plectranthus amboinicus (Lour.) Spreng essential oil on the anti-Candida activity of some clinically used antifungals

Plants with medicinal properties have been applied for a long in the traditional health care, so that sometimes their use takes place concomitantly to the use of industrialized drugs. The aim of this study was to evaluate the interference of Plectranthus amboinicus essential oil on the anti-Candida activity of some clinically used antifungals by the solid medium diffusion procedure. Assayed antifungals were amphotericin B (100 µg/mL), ketoconazole (50 µg/mL) and itraconazole (50 µg/mL). C. albicans, C. tropicalis, C. guilliermondii, C. krusei and C. stellatoidea were used as test microorganisms. P. amboinicus essential oil showed MIC value for most assayed yeast strains. The essential oil when assayed in its MIC value showed some interference on the anti-Candida effectiveness of the assayed antifungals. It was noted yeast growth inhibition zones with different diameters when the antifungals were tested alone and combined with the essential oil. P. amboinicus essential oil showed prominent interference on the anti-yeast activity of itraconazole providing a synergic effect on C. albicans, C. tropicalis, C. krusei and C. stellatoidea. Also, the essential oil interfered on the anti-yeast activity of ketoconazole when interacting with C. albicans, C. guilliermondii and C. stellatoidea providing, respectively, an antagonic and synergic effect. On the other hand, it was found a small interference on the anti-yeast effect of amphotericin B. These data showed that combined use of medicinal plants and/or derivatives with industrialized drugs, particularly antimicrobials, could interfere on their expected therapeutic effects.As plantas com propriedades medicinais tem sido utilizadas por um longo tempo no cuidado tradicional de saude, de modo que algumas vezes seu uso ocorre concomitantemente ao uso de drogas industrializadas. O objetivo deste estudo foi avaliar a interferencia do oleo essencial de Plectranthus amboinicus sobre atividade anti-Candida de alguns antifungicos utilizados clinicamente atraves do metodo de difusao em meio solido. Os antifungicos ensaiados foram anfotericina B (100 µg/mL), cetoconazol (50 µg/mL) e itraconazol (50 µg/mL). C. albicans, C. tropicalis, C. guilliermondii, C. krusei e C. stellatoidea foram utilizadas como microrganismos testes. O oleo essencial de P. amboinicus mostrou um valor de CIM de 40 µL/mL para a maioria das cepas de leveduras ensaiadas. O oleo essencial quando ensaiado em sua CIM mostrou alguma interferencia sobre a efetividade anti-Candida dos antifungicos testados, sendo notada a formacao de zonas de inibicao do crescimento fungico com diferentes diâmetros quando os antifungicos foram testados isolados e em combinacao com o oleo essencial. O oleo essencial de P. amboinicus mostrou destacavel interferencia sobre a atividade antifungica de itraconazol, sendo observado um efeito sinergico sobre C. albicans, C. tropicalis, C. krusei e C. stellatoidea. Ademais, o oleo essencial interferiu na atividade antifungica de cetoconazol sobre C. albicans, C. guilliermondii e C. stellatoidea causando, respectivamente, efeito antagonico e sinergico. De outra forma, foi observada uma pequena interferencia do oleo essencial sobre o efeito antifungico de anfotericina B. Estes dados mostram que o uso combinado de plantas medicinais e/ou seus produtos derivados com drogas industrializadas, particularmente, antimicrobianos podem interferir sobre os efeitos terapeuticos esperados.

Antifungal activity and mode of action of carvacrol against Candida albicans strains

In this study, the minimal inhibitory concentration (MIC), minimal fungicidal concentration (MFC) and mode of action of carvacrol were determined. MIC was determined according to the standard broth microdilution method, and MFC was taken as the lowest concentration in culture plates with Sabouraud dextrose agar, at which growth was less than 3 CFU. The effect of ergosterol or sorbitol on carvacrol was investigated using the broth microdilution method. MIC was 256 μg/mL and MFC was 512 μg/mL. This phytoconstituent acts by binding to sterols in the fungal membrane and does not act by modifying the fungal cell wall. This study is important because it shows the mode of action of carvacrol. However, more studies are necessary to define the exact mechanism of action.

Inhibitory effect of some phytochemicals in the growth of yeasts potentially causing opportunistic infections

Opportunistic infections caused by yeasts have been characterized as emerging diseases all over the world and this has caused the search for new products capable of inhibiting the survival of their etiological agents. In this study the sensitivity of some yeast potentially causing infections to a-pinene, b-pinene, citral and eugenol was evaluated. All phytochemicals showed inhibitory action on the assayed yeast strains: Candida. albicans, C. tropicalis, C. guilliermondii, C. stellatoidea, C. krusei, C. parapsilosis and Cryptococcus neoformans, presenting their MIC values in the range of 1 and 4%. The phytochemicals presented effectiveness to provide high fungicide effect in a short time. These data support the possible use of some phytochemicals as useful tools to control the occurrence of opportunistic infections caused by yeasts.

Antifungal activity of Cymbopogon winterianus jowitt ex bor against Candida albicans

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.

Anti-Candida albicans effectiveness of citral and investigation of mode of action.

Context: Candidiasis is a mycosis caused by Candida species, which is of clinical importance due to the increase in resistant yeasts. Candida infection has been a serious health problem due to the inappropriate use of antibiotics. Therefore, it is necessary to study molecules with an antifungal action. Citral is a monoterpene with known pharmacological properties, including antimicrobial action. Objective: The aim of this work was to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of citral and the probable mode of action. Materials and methods: The MIC of citral was determined by the broth microdilution method using Sabouraud dextrose medium. Additionally, the interference of citral in cell wall (sorbitol assay) and the binding of citral to ergosterol and cholesterol were studied, carried out by broth microdilution method. Results: The MIC and MFC of citral were 512 and 1024 µg/mL, respectively. The MIC of amphotericin B was 1 µg/mL. The mechanism of action did not involve either the cell wall or ergosterol. However, the presence of cholesterol increased the MIC of citral to 1024 µg/mL, indicating there is some interaction between citral and cholesterol. Amphotericin B was used as the positive control, and it showed a high MIC in the presence of ergosterol (32 µg/mL), while in the presence of cholesterol MIC increased to 4 µg/mL. Conclusion: Citral inhibits the growth of C. albicans. The probable mechanism of action did not involve the cell wall or ergosterol. Citral is able to interact with cholesterol. More studies are necessary to describe their effects completely.

Docking and PLS Studies on a Set of Thiophenes RNA Polymerase Inhibitors Against Staphylococcus aureus

Staphylococcus aureus lives in commensalism with the majority of the population, being recognized as an important pathogen in patients with chronic liver diseases and can cause a deadly infection. The use of antibiotics as rifampin for the chemotherapy of infections caused by S. aureus has resulted in the selection of mutants with resistance. In an attempt to combat resistant strains new research is continuously conducted, as example searching new biological targets or new inhibitors such as tiophenes derivatives that can inhibit the RNA polymerase enzyme. This work investigated the set of tiophenes, selected from of literature and with RNA polymerase enzyme inhibitory activity of S. aureus. After seeking further information on existing scientific literature, the compounds under study were applied the methodologies of PLS, docking and calculation of Molecular Interaction Fields (MIFs) using Pentacle and VolSurf programmes. In addition, a comparison was made with two tiophenes synthesized in our laboratory and which have been tested against the bacteria. Docking studies showed that active compounds had more interactions with the amino acids on active site when compared with rifampicin. The best model obtained in PLS, considering two LVs (latent variables), after leave-one-outvalidation, exhibited the statistical parameters qcv(2) = 0.68 and r(2) = 0.85. External prediction model presented a rext(2) = 0.67. The obtained model through PLS analyses was able to predict the behavior of compounds synthesized by us. So we extract structural features important for the activity of these compounds. In this paper, first we discussed the topics: S. aureus, tiophenes, RNA polymerase, docking and QSAR methodologies. Then we have selected a series of 56 tiophenes from literature, which have their biological activity tested against the RNA polymerase enzyme of S. aureus. The compounds were subsequently carried out for Partial Least Squares (PLS) Analysis.