Atividade antimicrobiana e larvicida de óleos fixos e extratos brutos de cinco espécies vegetais da Amazônia

Abstract

Introduction: In recent decades, the use of natural or synthetic drugs in an abusive and indiscriminate manner, has taken many strains of microorganisms from a series of resistors and multiresistants, becoming a worldwide problem, being a confrontation to the researchers. Similarly, the continuous and indiscriminate use of chemical insecticides does not apply to transmitters of pests and diseases, such as the Aedes aegypti transmitter dengue, chikungunia, zica and yellow fever, resistance selection. OBJECTIVE: The objective of this study was to investigate the in vitro antibacterial and larvicidal effect of the fixed oils (FOs) of Bertholletia excelsa HBK and Astrocaryum aculeatum Meyer and the crude methanolic extracts (CMEs) of Pentaclethra macroloba (Willd.) Kuntze, Parahancornia amapa (Huber) Ducke and Amasonia campestris (Aubl.) Moldenke. Methods: The FOs of B. excelsa and A. aculeatum were obtained by hydraulic pressing. The CMEs of P. macroloba, P. amapa and A. campestris through solvents (methanol). For the antibacterial activity, the agar diffusion method (discs and wells) at the concentrations of 125, 250 and 500 mg/mL dissolved in dimethylsulfoxide (DMSO) and 2,3-diethylcloroethane (A. aculeatum) were used and the determination of Minimum inhibitory concentration, by the 96-well plate microdilution method, against standard strains of bacteria: Staphylococcus aureus (3 strains), Streptococcus pneumoniae subsp. pneumoniae, Escherichia coli (2 strains), Proteus mirabilis, Klebsiella pneumoniae, Salmonella typhimurium and Pseudomonas aeruginosa. For the larvicidal activity the larvae of Aedes aegypti (Rockefeller Lineage) in the 3rd instar, the concentrations of 12.5, 25.0 and 50.0 μg.mL-1 were exposed of the FOs and CMEs in the period of 24 and 48 h and the data obtained were submitted to Probit analysis for LC50 and LC90 determination. Results and discussion: The CME of P. macroloba presented inhibitory potential against 80% of the bacteria in the study (S. aureus - 3 strains, E. coli, P. mirabilis, K. pneumoniae, S. typhimurium and P. aeruginosa). In the larvicidal activity it presented LC50=9,338 and LC90=73,528 after 24 h and LC50=5,39649 and LC90= 46,2339 after 48 h of larval exposure. The CME of P. amapa showed inhibitory potential against 40% of the study bacteria (S. aureus - 2 strains, E. coli and P. aeruginosa) and did not present larvicidal activity. The CME of A. campestris showed inhibitory potential against 40% of the study bacteria (S. aureus - 3 strains and P. aeruginosa) and low larvicidal activity at study concentrations. The FOs did not present inhibitory efficacy against the bacteria of the study, but in the larvicidal activity the FO of B. excelsa presented LC50=28.89 after 48 h of larval exposure. The FO of A. aculeatum had no larvicidal activity. Conclusions: The species P. macroloba has been shown to be pharmacologically promising, showing a better effectiveness in both activities, standing out from the others. Studies on the pharmacological properties of P. amapa and A. campestris species are scarce. The results of the antimicrobial activity for the species A. campestris are pioneers, as well as in the larvicidal activity for these two species