Antifungal activity of liriodenine on agents of systemic mycoses, with emphasis on the genus Paracoccidioides

Endemic systemic mycoses remain a health challenge, since these opportunistic diseases are increasingly infecting immunosuppressed patients. The simultaneous use of antifungal compounds and other drugs to treat infectious or non-infectious diseases has led to several interactions and undesirable effects. Thus, new antifungal compounds should be investigated. The present study aimed to evaluate the activity of liriodenine extracted from Annona macroprophyllata on agents of systemic mycoses, with emphasis on the genus Paracoccidioides. Methods: The minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were determined by the microdilution method. The cellular alterations caused by liriodenine on a standard P. brasiliensis (Pb18) strain were evaluated by transmission and scanning electron microscopy. Results: Liriodenine was effective only in 3 of the 8 strains of the genus Paracoccidioides and in the Histoplasma capsulatum strain, in a very low concentration (MIC of 1.95 µg.mL-1); on yeasts of Candida spp. (MIC of 125 to 250 µg.mL-1), including C. krusei (250 µg.mL-1), which has intrinsic resistance to fluconazole; and in Cryptococcus neoformans and Cryptococcus gattii (MIC of 62.5 µg.mL-1). However, liriodenine was not effective against Aspergillus fumigatus at the studied concentrations. Liriodenine exhibited fungicidal activity against all standard strains and clinical isolates that showed to be susceptible by in vitro tests. Electron microscopy revealed cytoplasmic alterations and damage to the cell wall of P. brasiliensis (Pb18). Conclusion: Our results indicate that liriodenine is a promising fungicidal compound that should undergo further investigation with some chemical modifications.(AU)

Thermoinhibition in parsley seeds / Termoinibição em sementes de salsa

Temperature can exert great influence on germination, being considered optimal the temperature in which seed expresses its maximum germination potential in the shortest period of time. The germination of parsley seeds is slow, irregular and uneven. The aim of this study was to determine whether there is occurrence of thermodormancy or thermoinhibition of parsley seeds as a function of temperature variations. The experimental design of the first stage was completely randomized (CRD) consisting of 7 temperatures and 4 replicates and the second stage in a 3x3 factorial scheme consisting of 3 parsley cultivars and 3 germination temperatures with 4 replicates. Seeds of the different cultivars did not germinate at temperature of 35°C. Parsley seeds showed thermoinhibition at high temperatures, being necessary to elucidate the mechanisms involved in this process.

A temperatura pode exercer grande influência na germinação, sendo considerada ótima aquela em que a semente expressa seu potencial máximo de germinação no menor período de tempo. A germinação das sementes de salsa é lenta, irregular e desuniforme. O objetivo do trabalho foi determinar se há ocorrência de termodormência ou de termoinibição em sementes de salsa em função da variação da temperatura. O delineamento experimental da primeira etapa foi inteiramente casualizado (DIC), constituído por 7 temperaturas, com 4 repetições e a segunda etapa em esquema fatorial 3x3, constituído por 3 cultivares de salsa e 3 temperaturas para germinação com 4 repetições. As sementes das cultivares estudadas não germinaram em temperaturas de 35°C. Sementes de salsa apresentam termoinibição em temperaturas elevadas, sendo necessário elucidar os mecanismos que estão envolvidos nesse processo.

Enraizamento de estacas de atemoieira (Annona Cherimola Mill. x A. squamosa L.) cv. Gefner submetidas a tratamento lento e rápido com auxinas / Rooting of atemoya (Annona cherimola Mill. x A. squamosa L.) cv. Gefner cuttings subjected to slow and fast treatment with auxins

Realizou-se este trabalho, com o objetivo de avaliar o uso de concentrações de diferentes auxinas no enraizamento de estacas de atemoieira (Annona cherimola Mill. x A. squamosa L.) cv. Gefner, empregando-se tratamento lento e rápido. O delineamento experimental empregado foi inteiramente casualizado, em esquema fatorial 3x7 (auxinas x concentrações), com 5 repetições de 12 estacas por parcela, para cada método de aplicação de auxina (lento e rápido). As estacas foram tratadas com os reguladores vegetais, por meio da imersão da base em soluções, contendo IBA, NAA e 2,4-D, durante 24 horas (tratamento lento) nas concentrações 0 (testemunha), 50, 100, 200, 300, 400 e 500 mg L-1 de cada regulador e 5 segundos (tratamento rápido) nas concentrações 0 (testemunha), 500, 1000, 2000, 3000, 4000 e 5000 mg L-1 de cada regulador. As variáveis avaliadas foram: porcentagem de estacas sobreviventes, enraizadas, sobreviventes com calos, comprimento de raiz por estaca, porcentagem de estacas enraizadas com folhas remanescentes, com brotação e com folhas remanescentes e brotação. Para o enraizamento de estacas de atemoieira cv. 'Gefner' conclui-se que, o tratamento lento, com 200 mg L-1 de NAA, proporcionou incremento ao processo, da mesma forma que o tratamento rápido com IBA, independente da concentração.

This study aimed to evaluate the effect of different auxin concentrations in the rooting of atemoya (Annona cherimola Mill. x A. squamosa L.) cv. Gefner stacks, employing slow and fast treatments. The experimental design used was completely randomized, in 3x7 factorial arrangement (auxins x concentrations), with 5 replicates of 12 stacks per plot, for each auxin application method (slow and fast). Stacks were treated with plant growth regulators by bottom immersion in a solution containing IBA, NAA and 2,4-D for 24 hours (slow treatment) at the following concentrations: 0 (control), 50, 100, 200, 300, 400 and 500 mg L-1 of each growth regulator and for 5 seconds (fast treatment) at the concentrations: 0 (control), 500, 1000, 2000, 3000, 4000 and 5000 mg L-1 of each growth regulator. The evaluated variables were: percentage of surviving, rooted and surviving-with-callus stacks; root length per stack; percentage of rooted stacks with remaining leaves, sprouting, and remaining leaves and sprouting. For the rooting of stacks of atemoya cv. 'Gefner', it was concluded that the slow treatment with 200 mg L-1 of NAA increased the rooting process, similar to fast treatment with IBA, regardless of concentrations.