Estudos da atividade antifúngica dos óleos essenciais e hidrolatos de resinas de Protium altsonii no controle de fitopatógenos

Abstract

The use of fungicides to control phytopathogenic fungi is considered a major challenge for global agriculture, since the use of these products is associated with several environmental problems and harm to human health. In this context, vegetable essential oils are a promising alternative to synthetic pesticides used in agricultural production. Oleoresins from the species Protium altsonii have biological activities and represent a sustainable alternative for the development of efficient biopesticides for the control of phytopathogens. This study aimed to evaluate the antifungal potential of Protium altsonii oleoresins, its essential oils and hydrolates in the control of pathogenic fungi. The fungi Alternaria japonica, Colletotrichum guaranicola, Colletotrichum spp. and Pestalotiopsis spp. were evaluated. The oleoresin samples from P. altsonii (28 g and 33 g) were subjected to hydrodistillation in Clevenger for 3 hours. The essential oils and hydrolates were collected and kept under refrigeration. The obtained essential oils were subjected to gas chromatography (GC-MS) analysis to quantify their chemical composition. The determination of antifungal activity was performed by the disk diffusion method. The determination of the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were performed by the microdilution method in wells and in Petri dishes containing sterile potato dextrose broth, respectively. The GC-MS analyses allowed the identification of 34 constituents for the BRALT01 sample, with a predominance of monoterpenes (73.22%) and sesquiterpenes (24.41%). The major constituents were p-cymene (34.73%), α-phellandrene (13.86%), α-pinene (6.85%) and β-acoradiene (9.62%). In sample BRALT02, 25 constituents were identified, with a predominance of monoterpenes (90.21%) and sesquiterpenes (8.45%). The major components were p-cymene (51.6%), trans-dihydro-α-terpineol (15.1%), α-pinene (6.92%), α-terpinene (3.77%) and α-phellandrene (3.34%). The essential oils BRALT01 and BRALT02 showed antifungal activity against the fungi Alternaria japonica, Colletotrichum guaranicola, Colletotrichum spp. with the formation of inhibition halos above 1.0 cm. The BRALT02 oil showed better results for antifungal activity (inhibition zones between 1.70 cm-1.95 cm) compared to the BRALT01 oil (inhibition zones between 1.19-1.45 cm) for A. japonica, C. guaranicola and Colletotrichum spp. The oils did not show antifungal activity for Pestalotiopsis spp. The hydrolates did not show antifungal activity for any phytopathogen tested. The BRALT02 oil was more efficient than the BRALT01 oil, presenting the lowest MIC and CFM values for all pathogens tested. Protium altsonii resin essential oils are a promising alternative for the control of phytopathogens, representing a lower risk to human health and the environment