Evandro Leite de Souza

Inhibitory action of some essential oils and phytochemicals on the growth of various moulds isolated from foods

The aim of this study was to determine the sensitivity profile of mould strains isolated from foods to some essential oils and phytochemicals. The assayed mould strains were: Fusarium spp., Rhizopus spp., Aspergillus flavus, A. niger and Penicillium spp. According to results, Lippia alba N.E. Brown, Peumus boldus Molina, Lippia microphylla Phil., Citrus limon Risso and Cymbopogon citratus Stapf. essential oil and the phytochemicals citral, eugenol and mircene showed prominent antimould activity. Among the products that evidenced antimould activity, citral and eugenol showed the lowest minimum inhibitory concentrations, which was 1% and 4%, respectively, for the most of the tested mould strains.

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.

Efficacy of the application of a coating composed of chitosan and Origanum vulgare L. essential oil to control Rhizopus stolonifer and Aspergillus niger in grapes (Vitis labrusca L.).

This study evaluated the efficacy of the combined application of chitosan (CHI) and Origanum vulgare L. essential oil (OV) in the inhibition of Rhizopus stolonifer URM 3728 and Aspergillus niger URM 5842 on laboratory media and on grapes (Vitis labrusca L.) and its influence on the physical, physicochemical and sensory characteristics of the fruits during storage (25 °C, 12 days and 12 °C, 24 days). The application of mixtures of different CHI and OV concentrations (Minimum Inhibitory Concentration - MIC, 1/2 MIC and 1/4 MIC) inhibited the mycelial growth of the test fungi. The application of CHI and OV at sub-inhibitory concentrations (CHI 1/2 MIC + OV 1/4 MIC; CHI 1/2 MIC + OV 1/2 MIC) inhibited spore germination and caused morphological changes in fungal spores and mycelia, in addition to inhibiting the growth of the assayed fungi strains in artificially infected grapes as well as the autochthonous mycoflora of grapes stored at both room and cold temperature. In general, the application of a coating composed of CHI and OV at sub-inhibitory concentrations preserved the quality of grapes as measured by their physical and physicochemical attributes, while some of their sensory attributes improved throughout the assessed storage time. These results demonstrate the potential of the combination of CHI and OV at sub-inhibitory concentrations to control post-harvest pathogenic fungi in fruits, in particular, R. stolonifer and A. niger in grapes.

Inhibition of Staphylococcus aureus in broth and meat broth using synergies of phenolics and organic acids.

This study assessed the occurrence of an enhancing inhibitory effect of the combined application of thymol and carvacrol with lactic and acetic acid against Staphylococcus aureus using the determination of Fractional Inhibitory Concentration (FIC) index and kill-time assay in meat broth and in a food model (meat). Minimum Inhibitory Concentration (MIC) of carvacrol and thymol were 1.25 and 0.6 microL/mL, respectively. FIC indices of the combined application of the phenolic constituents and organic acids were 0.5 suggesting a synergic interaction. No difference (p>0.05) was found among the bacterial counts for the meat broth added of the phenolics alone or in combination with lactic acid at sub-inhibitory concentrations. Contrarily, the bacterial counts found for the meat broth added of the phenolics alone were significantly lower (p<0.05) than the counts obtained for the broth added of the combination of phenolics and acetic acid. No difference (p>0.05) was found among the bacterial counts for the meat model added of phytochemicals alone and in combination with the organic acids. The tested antimicrobials alone or in mixture provided smaller anti-staphylococcal effect in meat broth than in meat model. These results could arise as an interesting approach for the improvement of food preservation using more natural procedures, considering the current demand of consumer and sensory quality of foods.

The potential of Origanum vulgare L. (Lamiaceae) essential oil in inhibiting the growth of some food-related Aspergillus species

Origanum vulgare L. (Lamiaceae) has been currently known for their interesting antimicrobial activity being regarded as alternative antimicrobial for use is food conservation systems. This study aimed to evaluate the effectiveness of O. vulgare essential oil in inhibiting the growth of some food-related Aspergillus species (A. flavus, A. parasiticus, A. terreus, A. ochraceus, A. fumigatus and A. niger). The essential oil revealed a strong anti-Aspergillus property providing an inhibition of all assayed mould strains. MIC values were between 80 and 20 μL/mL being found a MIC50 of 40 μL/mL. The essential oil at concentration of 80 and 40 μL/mL provided a fungicidal effect on A. flavus, A. fumigatus and A. niger noted by a total inhibition of the radial mycelial growth along 14 days of interaction. In addition, the essential oil was able to inhibit the mould spores germination when assayed at concentrations of 80 and 40 μL/mL. Our results showed the interesting anti-Aspergillus activity of O. vulgare essential oil supporting their possible use as anti-mould compound in food conservation.

Effectiveness of Lippia sidoides Cham. (Verbenaceae) essential oil in inhibiting the growth of Staphylococcus aureus strains isolated from clinical material

Staphylococcus aureus apresenta-se como um microrganismo patogenico classico sendo comumente reconhecido como agente etiologico de infeccoes comunitarias e hospitalares. Considerando o conhecimento acerca das propriedades biologicas apresentadas por Lippia sidoides Cham. (Verbenaceae), este estudo teve como objetivo avaliar a efetividade de seu oleo essencial em inibir o crescimento de cepas de S. aureus com diferentes perfis de resistencia antibiotica isoladas de material clinico. Os resultados mostraram destacavel atividade anti-S. aureus do oleo essencial de L. sidoides notada por grandes halos de inibicao do crescimento bacteriano (15-21 mm). A CIM encontrada foi de 0.4 µL/mL para todas as cepas ensaiada. A CIM apresentou destacavel efetividade de inibicao da viabilidade de S. aureus em caldo durante vinte e quatro horas de interacao caracterizando um efeito bacteriostatico. Estes resultados mostram a destacavel atividade antiestafilococica do oleo essencial de L. sidoides, bem como suportam a possibilidade de seu uso racional como agente antimicrobiano alternativo.

Effect of cinnamomum zeylanicum blume essential oil on the rowth and morphogenesis of some potentially pathogenic Aspergillus species

Cinnamomum zeylanicum Blume is known for a wide range of medicinal properties. This study aimed to assess the interference of C. zeylanicum essential oil on the growth and morphogenesis of some potentially pathogenic Aspergillus species. The essential oil presented strong antifungal effect causing the growth inhibition of the assayed strains and development of large growth inhibition zones. MIC50 and MIC90 values were 40 and 80 µL/mL, respectively. 80, 40 and 20 µL/mL of the oil strongly inhibited the radial mycelial growth of A. niger, A. flavus and A. fumigatus along 14 days. 80 and 40 µL/mL of the oil caused a 100% inhibition of the fungal spore germination. Main morphological changes observed under light microscopy provided by the essential oil in the fungal strains were decreased conidiation, leakage of cytoplasm, loss of pigmentation and disrupted cell structure indicating fungal wall degeneration. It is concluded that C. zeylanicum essential oil could be known as potential antifungal compound, particularly, to protect against the growth of Aspergillus species.

CHEMICAL COMPOSITION AND ANTIFUNGAL ACTIVITY OF HYPTIS SUAVEOLENS (L.) POIT LEAVES ESSENTIAL OIL AGAINST ASPERGILLUS SPECIES

This study aimed to identify the constituents of the essential oil from Hyptis suaveolens (L.) leaves using a Gas Chromatograph - Mass Spectrometer and assess its inhibitory effect on some potentially pathogenic Aspergilli (A. flavus, A. parasiticus, A. ochraceus, A. fumigatus and A. niger). Eucaliptol (47.64 %) was the most abundant component in the oil, followed for gama-ellemene (8.15 %), beta-pynene (6.55 %), (+)-3-carene (5.16 %), trans-beta-cariophyllene (4.69 %) and germacrene (4.86 %). The essential oil revealed an interesting anti-Aspergillus property characterized by a Minimum Inhibitory Concentration and Minimum Fungicidal Concentration of 40 and 80 µL/mL, respectively. The oil at 80 and 40 µL/mL strongly inhibited the mycelial growth of A. fumigatus and A. parasiticus along 14 days. In addition, at 10 and 20 µL/mL the oil was able to cause morphological changes in A. flavus as decreased conidiation, leakage of cytoplasm, loss of pigmentation and disrupted cell structure suggesting fungal wall degeneration. These findings showed the interesting anti-Aspergillus property of H. suaveolens leaves essential oil supporting its possible rational use as alternative source of new antifungal compounds to be applied in the aspergillosis treatment.

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.