Antifungal activity of five species of Polygala

Crude extracts and fractions of five species of Polygala - P. campestris, P. cyparissias, P. paniculata, P. pulchella and P. sabulosa - were investigated for their in vitro antifungal activity against opportunistic Candida species, Cryptococcus gattii and Sporothrix schenckii with bioautographic and microdilution assays. In the bioautographic assays, the major extracts were active against the fungi tested. In the minimal concentration inhibitory (MIC) assay, the hexane extract of P. paniculata and EtOAc fraction of P. sabulosa showed the best antifungal activity, with MIC values of 60 and 30 µg/mL, respectively, against C. tropicalis, C. gattii and S. schenckii. The compounds isolated from P. sabulosa prenyloxycoumarin and 1,2,3,4,5,6-hexanehexol displayed antifungal activity against S. schenckii (with MICs of 125 µg/mL and 250 µg/mL, respectively) and C. gattii (both with MICs of 250 µg/mL). Rutin and aurapten isolated from P. paniculata showed antifungal activity against C. gattii with MIC values of 60 and 250 µg/mL, respectively. In the antifungal screening, few of the isolated compounds showed good antifungal inhibition. The compound á-spinasterol showed broad activity against the species tested, while rutin had the best activity with the lowest MIC values for the microorganisms tested. These two compounds may be chemically modified by the introduction of a substitute group that would alter several physico-chemical properties of the molecule, such as hydrophobicity, electronic density and steric strain.

Genetic variability analysis among clinical Candida spp. isolates using random amplified polymorphic DNA

The patterns of genetic variation of samples of Candida spp. isolated from patients infected with human immunodeficiency virus in Vitória, state of Espírito Santo, Brazil, were examined. Thirty-seven strains were isolated from different anatomical sites obtained from different infection episodes of 11 patients infected with the human immunodeficiency virus (HIV). These samples were subjected to randomly amplified polymorphic DNA (RAPD) analysis using 9 different primers. Reproducible and complex DNA banding patterns were obtained. The experiments indicated evidence of dynamic process of yeast colonization in HIV-infected patients, and also that certain primers are efficient in the identification of species of the Candida genus. Thus, we conclude that RAPD analysis may be useful in providing genotypic characters for Candida species typing in epidemiological investigations, and also for the rapid identification of pathogenic fungi.

Occurrence and diel distribution of yeast in a paleo-karstic lake of southeastern Brazil

Foram estudadas a distribuiçäo sazonal e diuturna de leveduras na coluna d`agua da Lagoa Santa, um lago paleocárstico de Minas Gerais. A possível influência de parâmetros ambientais nas populaçöes fúngicas e na ocorrência das espécies de leveduras foi examinada. O lago mostrou homogeneidade térmica e coluna d`agua oxigenada durante o mês de junho, e estratificaçäo da temperatura e oxigênio dissolvido durante o período de setembro a março. A diversidade de espécies de leveduras diminuiu de acordo com o aumento da profundidade, provavelmente devido ao metabolismo oxidativo predominante entre as leveduras que poderia limitar sua distribuiçäo às águas oxigenadas da superfície. As espécies mais frequentes foram Crypococcus flavus, Rhodotorula minuta, Trichosporum cutaneum. Tr. pullulans e Aureobasidum pullulans. As contagens de leveduras e a diversidade de espécies foram maiores nos meses chuvosos de dezembro e março, e menores na estaçäo seca. Trichosporon cutaneum mostrou populaçöes elevadas na estaçäo seca, e poderia ser considerada uma espécie indígena do lago. A predominância de espécies oxidativas politróficas e pigmentadas sugere que a micobiota da Lagoa Santa é originária de solos e superfícies foliares. As populaçöes de leveduras da Lagoa Santa säo provavelmente mantidas pelo efluxo constante de espécies transitórias nas águas da chuva e dos afluentes do lago