RESUMO -(Análise do potencial fitotóxico de extratos foliares de Aloe arborescens Miller (Asphodelaceae) produzidos em diferentes épocas do ano). Este trabalho visou analisar o potencial fitotóxico de extratos foliares de Aloe arborescens Miller sobre a germinação e crescimento de plântulas de alface (Lactuca sativa L.). Amostras de folhas foram coletadas nas quatro estações climáticas e maceradas em etanol P.A. por 28 dias. Os extratos produzidos foram fracionados em extratos etanólico e clorofórmico e tiveram as concentrações reduzidas a 1%. Os bioensaios de ação fitotóxica foram desenvolvidos em triplicata, sob luz constante e temperatura ambiente. Apenas o extrato clorofórmico de primavera mostrou forte atividade fitotóxica sobre a germinação das sementes de alface (16,67%). Todos os extratos reduziram significativamente a primeira contagem, índice de velocidade germinação (IVG) e o crescimento do eixo hipocótilo-radicular (EHR) das plântulas de alface, porém os extratos clorofórmicos mostraram maior atividade fitotóxica, gerando alterações morfológicas mais intensas sobre as plântulas de alface e apresentaram maiores teores de compostos fenólicos. Apesar de todos os extratos clorofórmicos inibirem fortemente o crescimento das folhas cotiledonares das plântulas de alface, não se observaram neste último efeito, variações em função dos períodos de coleta. Palavras-chave: alelopatia, Aloe, fitotoxicidade, sazonalidade ABSTRACT -(Analysis of the phytotoxic potential of Aloe arborescens Miller leaf extracts (Asphodelaceae) produced at different times of the year). This study aimed to analyze seasonal variation in the phytotoxic potential of Aloe arborescens Miller leaf extract on lettuce (Lactuca sativa L.) germination and growth. Leaf samples were collected in the four seasons and were macerated in ethanol P.A. for 28 days. The extracts were fractionated into solutions made with ethanol and chloroform, and concentrations were reduced to 1%. Phytotoxic activity bioassays were carried out in triplicate, under constant light and ambient temperature. Only the spring chloroform extract showed strong phytotoxic activity on lettuce seed germination (16.67%). All extracts significantly reduced the first count, germination velocity index (GVI) and growth of the hipocotyl-root axis (HRA) of the lettuce plants. However, the chloroform extracts showed greater phytotoxic activity, producing more intense morphology alterations on lettuce plants and showed greater content of phenolic compounds.
"Seasonal analysis from the antimicrobial potency and flavonoid and quinone content from Aloe arborescens Mill., Xanthorrhoeaceae, leaf extracts". This work has the objective of evaluate the antimicrobial potency and the content of flavonoids and quinones from the Aloe arborescens Mill., Xanthorrhoeaceae, leaf extracts produced in the four seasons of the year. Ethanol and chloroform extracts were prepared from the leaves, the bioassays from antimicrobial activity were developed by the macrodilution method in broth, and dosages of flavonoids and quinones were performed in the extracts. The winter chloroform extract showed the lowest CIM (128 µg/mL) on B. subtilis. The ethanol extract showed the lowest CIM (256 µg/ mL) and the lowest CMM (512 µg/mL) on K. pneumoniae. The summer and fall ethanol extracts showed low antimicrobial activity. The quinones extracts showed inhibitory activity on the tested microorganisms. The winter, spring and summer chloroform extracts showed higher antimicrobial activity compared to the fall chloroform one. The winter ethanol extract content from the leaves were higher in the hotter periods of collection (summer and fall) and the flavonoids content were similar in the four collection periods.
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