The pericarp and seeds from fruits of Garcinia brasiliensis were subjected to extraction with hexane and ethanol. The pericarp hexane extract (PHE) and seed ethanol extract (SEE) were purified by silica gel column chromatography, which permitted isolation of the prenylated benzophenones 7-epiclusianone (1) and guttiferone-A (2), respectively. The antimicrobial activity of PHE, SEE, and compounds 1 and 2 were evaluated against Candida albicans, Staphylococcus aureus, Escherichia coli, and Bacillus cereus cultures. The minimum inhibitory concentration and minimum bactericidal concentration were established. The substances presented activity against S. aureus and B. cereus as follows: PHE, 4.0 microg/mL and 2.4 microg/mL; SEE, 10.0 microg/mL and 12.6 microg/mL; 7-epiclusianone, 1.2 microg/mL and 0.6 microg/mL; and guttiferone-A, 2.4 microg/mL and 2.4 microg/mL, respectively. The direct relationship between the lipophilic character of the structure and activity in Gram-positive bacteria was specifically observed. Therefore these extracts and prenylated benzophenones represent an interesting topic for further studies and open possibilities for an alternative control of diseases associated with Gram-positive bacteria.
Several studies have reported the occurrence of infections caused by Candida yeasts as well as the increasing prevalence of non albicans species. The aim of the present work is focused on the obtaining of heteroresistance to amphotericin B and fluconazole in Candida species using two distinct methodologies: selection and induction. Resistant samples were obtained by selective pressure using a medium with fluconazole for growth, followed by growth in a medium with amphotericin B. The selective pressure was also created beginning with growth in amphotericin B medium followed by growth in fluconazole medium. Concomitantly, samples were submitted to the induction of resistance through cultivation in increasing concentrations of fluconazole, followed by cultivation in increasing concentrations of amphotericin B. Subsequently, the induction began with amphotericin B followed by fluconazole. Three samples resistant to fluconazole and amphotericin B were obtained, two by induction (C. glabrata and C. tropicalis) and one by selection (C. tropicalis). Both C. tropicalis originated from the same wild sample.After successive transfers for drug free medium, only the sample obtained by selection was able to maintain the resistance phenotype. These results suggest that the phenotype of heteroresitance to fluconazole and amphotericin B can be produced by two methodologies: selection and induction.
The antifungal minimal inhibitory concentrations (MIC) were determined to 35 samples of Candida albicans; 14 of them were isolated from HIV-positive patients, and 21 from HIV-negative patients with oral erythematous candidosis. The aim of this study was to evaluate the performance of agar dilution method in the determination of susceptibility of Candida albicans isolated from buccal lesions of HIV-positive and negative patients to some antifungals and compare the results with the plasmatic concentration reached by each one of these drugs. The samples were evaluated in vitro by the agar dilution method and showed higher MIC values to ketoconazole, fluconazole, itraconazole and amphotericin B than the concentrations achieved by these antifungals in plasma. 88.9% of the samples presented in vitro resistance to ketoconazole and the plasmatic levels of this antifungal varied from 1 to 8 µg/mL. Regarding fluconazole and itraconazole, most samples presented MIC larger than 128 µg/mL and plasmatic concentration varying from 0.4 to 8 µg/mL. Only 11.9% of the samples were susceptible in vitro to fluconazole and 2.7% of them to itraconazol. The usage concentrations prescribed for the topical antifungals nystatin, fenticonazole and miconazole are markedly higher than the values of MIC obtained. Related to nystatin, it was verified that its MIC values were between 1 and 4 µg /mL. The plasmatic levels to this drug are extremely low. Fenticonazole presented a MIC value larger than 128 µg/mL. Relating to miconazole, the plasmatic levels vary from 1 to 8 µg/mL and 11.9% of the samples presented in vitro susceptibility to this drug. No significant differences (p<0.05) were found in the susceptibility profiles of the samples obtained from HIVpositive and HIV-negative patients.
A candidíase é uma infecção fúngica causada por leveduras do gênero Candida que vivem nas mucosas e só causam doença quando existem condições que favoreçam o seu crescimento, como nos pacientes imunodeprimidos infectados pelo vírus HIV. Os relatos de resistência verificados em isolados de Candida albicans, principalmente em pacientes imunocomprometidos, e a necessidade de um tratamento rápido e eficaz fazem com que haja um grande interesse em estudos que sejam capazes de utilizar testes de susceptibilidade ''in vitro'' para a escolha da terapia adequada. O objetivo deste trabalho foi de determinar a Concentração Inibitória Mínima (CIM) dos antifúngicos clotrimazol e terbinafina sobre 19 isolados de Candida albicans, oriundas de pacientes HIV positivos e HIV negativos com candidose oral eritematosa para detectar possível resistência. Utilizou-se a técnica de diluição de antifúngicos em agar e posterior inoculação das amostras em regiões demarcadas na placa de Petri. Verificou-se que a CIM para a terbinafina variou de 32 a 128 µg/mL enquanto que, para o clotrimazol, a CIM variou de 16 a 128 µg/mL. Este estudo nos permitiu concluir que a maioria das cepas de C. albicans isoladas apresentou valores de CIM elevados indicando resistência e estes não variaram de um antifúngico para outro, bem como não houve diferenças das CIM entre as amostras de pacientes HIV positivos e HIV negativos. Palavras-chave: candidiase bucal. terbinafina. clotrimazol.C. albicans. HIV Determination of Clotrimazole and Terbinafine Minimum Inhibitory Concentration on Candida albicans isolates from HIV-positive and HIV-negative patients oral mucosa Abstract: Candidiasis is a fungi infection caused by yeasts from Candida genus, that live in the mucosas and just causes illness when there are favoring conditions to its growth, like immune compromised HIV infected patients. Resistance reports verified in Candida albicans isolates, especially in those immune compromised, and fast and efficient treatment need cause there to be a great interest in studies capable of using in vitro susceptibility tests to adequate therapy choose. The objective of this study was to determine the Minimum Inhibitory Concentration (MIC) of antifungal agents clotrimazole and terbinafine on 19 isolates of Candida albicans isolated from HIV positive patients
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