A importância socioambiental de novos antifúngicos: O potencial das samambaias

• Autor(a) principal: Lancellotti, Isabella Rodrigues
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/12085
• topic: Pteridophytes; Leucoagaricus gongylophorus; Biological interactions; antifungals; Pteridófitas; Leucoagaricus gongylophorus; Interações biológicas; Antifúngicos; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA::ECOLOGIA APLICADA

Cutting ants of the genus Atta and Acromyrmex use fresh plant material as a substrate for the growth of their mutual fungus Leucoagaricus gongylophorus (A. Møller) Singer (Agaricaceae), from which they feed. This behavior makes the ant leafminer pests in agriculture and forestry. Studies have suggested that the presence of antifungal substances may influence the decision of leaf-cutting ants to forage a particular plant species. Thus, the search for insecticides and fungicides of plant origin has been revealed as a new strategy in the combat of these ants. The objective of the present study was to evaluate the antifungal activity of hydroalcoholic extracts of leaves of Dicksonia sellowiana Hook. (Dicksoniaceae), Macrothelypteris torresiana (Gaudich.) Ching (Thelypteridaceae) and Niphidium crassifolium (L.) Lellinger (Polypodiaceae), Lastreopsis effusa (Sw.) Tindale (Dryopteridaceae). The ferns were collected in October 2016 (dry season), at Itatiaia National Park, except L. effusa, collected at Espraiado, Maricá, Rio de Janeiro state and April 2017 (rainy season). The leaves were dried, then crushed and weighed. The extracts were prepared in the proportion of 1L of ethanol to 100g of sheet and concentrated in a rotary evaporator. For the assays, 1.0 ml aliquots of each extract diluted in 50 mg / mL ethanol were transferred to test tubes containing 9.0 mL of culture medium still liquefied, reaching the final concentration of 5 mg / ml. In a second step the final concentration of extracts was 100 μg / mL. The inoculum consisted of a mycelial suspension (7.3 mg p.s./ml) prepared from a culture with 30 days of development. The assays were performed in three-fold. Growth of the fungus was evaluated after 30 days of incubation at 25 ° C in the dark. The chemical profile (Phenolic substances and terpenoids) of the extracts was analyzed using the thin layer chromatography (TLC) method. Contrary to expected, the ethanol extract of L. effusa (5 mg/mL) completely inhibited the growth of the fungus mutualist, whereas the inhibition observed with the extracts of the other species was less than 50%. By decreasing the final concentration of the extracts (100 μg/mL), no inhibition of the symbiotic fungus growth occurred. Among the dry and rainy seasons there was greater similarity of terpenoids in Lastreopsis effusa (92.3%) and Dicksonia sellowiana (77.7%), however, a greater dissimilarity in the composition of phenolic compounds. In the species Macrothelypteris torresiana (62.5%) and Niphidium crassifolium (45.4%) there was greater similarity between the seasons of the year in relation to the phenolic compounds. The chemical profile analysis of the extracts indicated the presence of beta-sitosterol, friedelinol, rutin and canferol in some extracts. Lastreopsis effusa extracts present a potential in inhibition of the growth of Leucoagaricus gongylophorus, and further analysis of its chemical composition and minimum inhibitory concentration is necessary.