Atividade antimicrobiana do extrato alcoólico do fruto da Caesalpinia ferrea Mart frente a bactérias causadoras de mastite bovina
Tomaz, Klívio Loreno RaulinoAbrantes, Maria RocieneRocha, Manuella de Oliveira CabralOliveira, Adriene Rosceli Menezes deSoto-Blanco, BenitoFeijó, Francisco Marlon CarneiroSilva, Jean Berg Alves da
Background: The usual treatment of bovine mastitis is made with antimicrobial agents, which may cause bacterial resistance if used incorrectly. Herbal medicines have been used in an attempt to avoid this issue, but not all of them are scientifi cally proven to be effective against the agents that cause this disease. The Caesalpinia ferrea Mart. is a plant widely distributed in North and Northeast regions and has been studied for its several pharmacological properties, and it could be used as herbal medicine. Therefore, this study aimed at evaluating the antimicrobial activity of the alcoholic extract derived from the fruit of Caesalpinia ferrea Mart. against bacteria that cause bovine mastitis. Materials, Methods & Results: The study was divided in two sequential experiments. Experiment I was designed to evaluate the potential antimicrobial activity of the aqueous (extract 1) and the lyophilized (extract 2) solutions of the ethanolic residue fractionated with chloroform, as well as of the aqueous solution of the lyophilized ethanolic residue (extract 3) against twelve selected bacterial types (four standard isolates and eight ones from the field), as a trial for the next experiment. Using the same bacterial samples from the previous example, Experiment II evaluated the antimicrobial activity of the extract that had the best results in eight dilutions in Experiment I. This study was developed using the multi-well technique in triplicate. The extracts 1, 2 and 3 of the C. ferrea fruit presented antimicrobial activity against all bacteria analyzed; no statistical difference was observed between the means of the inhibition halos, with exception of the field isolate Staphylococcus aureus 3, in which the best results were obtained with extracts 1 and 2. Experiment II used extract 1 due to its ease of handling, and the results of the microbial inhibition halos decreased as the extract dilution increased. Additionally, field bacteria had a lower response in relation to standard bacteria kept in the laboratory. Upon analysis of the sensitivity of the bacteria to treatments through descriptive analysis, regardless of the bacterial isolate, we observed that all bacteria were sensitive to the initial and 1/1 dilutions. Sensitivity decreased after the 1/2 dilution (83.33%), reaching the minimum threshold at the 1/8 dilution (41.66%). Bacterial resistance was observed after the 1/16 dilution for 25% of the isolates, reaching 58.33% of the isolates in the 1/64 dilution. Discussion: This study was the first to use ethanolic extract (liquid and lyophilized) from the C. ferrea fruit in vitro against bacteria causing bovine mastitis, also demonstrating that the lyophilization process did not modify the antimicrobial activity of this extract, representing an alternative to storage, as well as a possibility to improve concentration control in studies and to prepare different formulations for in vivo studies. The fact that field bacteria had higher resistance to the extracts in comparison to standard isolates may be related to handling issues, since C. ferrea bark shavings are used in animal nutrition to treat clinical bovine mastitis. Consequently, Caesalpinia ferrea showed antimicrobial activity against all bacteria evaluated, and may be considered as a therapeutic option for the control of bovine mastitis on in vivo biological assays.
Texto completo