Avaliação do potencial antioxidante e antibacteriano de Anacardium microcarpum e sua toxicidade em diferentes modelos biológicos in vitro

Abstract

Oxidative stress reflects an imbalance between the systemic manifestation of reactive species and a biological system s ability to readily detoxify the reactive intermediates or to repair the resulting damage. This condition may facilitate the onset of various pathological processes, including infections. Anacardium microcarpum is a native species from the Northeast Brazil, used in folk medicine as a tonic for the treatment of inflammation, rheumatism, tumor, and infectious diseases. However, there is no information in the litterature regarding the involvement of antioxidant and antibacterial activities of A. microcarpum in its pharmacological properties, especially in relation to oxidative stress. Therefore, the first part of this study aimed at evaluating in vitro, the potential antioxidant of ethanolic, methanolic and ethyl acetate fractions from the stem barks of A. microcarpum using chemical and biological models, as well as their possible toxic effects in human leukocytes and erythrocytes. The results demonstrated that all the fractions (1-400 μg/mL) scavenged the 1,1-difenil-2-picrilhidrazila (DPPH) radical, and inhibited lipid peroxidation caused by Fe2+ (10 μM) in rat brain and liver homogenates. The fractions did not have any toxic effect on leukocytes and did not caused hemolysis of erythrocytes. Based on these results, the second part of this work was to investigate the antibacterial potential of these fractions against Escherichia coli, Pseudomonas aeruginosa and Sthapylococccus aureus, and their modulatory potential in combination with antibiotics drugs. The data revealed that all the fractions exhibited low antibacterial activity against multidrug resistant strains with minimal inhibitory concentration (MIC) of 512 μg/mL. However, the fractions showed notorious synergism with antibiotic drugs, especially from the class of aminoglycosides against E. coli, when they were added to the growth medium at the sub-inhibitory concentration (i.e., MIC/8 = 64 μg/mL). In conclusion, the results demonstrated for the first time the antioxidant activity of A. microcarpum which can be at least in part, attributed to its polyphenolic content. The possible interaction of chemical constituent from A. microcarpum with antibiotics may be associated with the modulation observed. Taken together, the use of A. microcarpum in traditional medicine has a scientific base and could be a promising source for the discovery of new drugs that could assist in the treatment of infectious diseases.