Antibacterial, cytotoxic and antioxidant effect of green leaf extract of Anacardium occidentale L.

Abstract

Anacardium occidentale has pharmacological potential of anti-inflammatory, healing, antimicrobial and gastroprotective characteristics. Thus, the objective of this study was to evaluate the antibacterial, cytotoxic and antioxidant effects of the green leaf extract of Anacardium occidentale against clinical and ATCC collection bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of selected strains of clinical importance and ATCC were determined. The effect of the association with licensed antibiotics reported in the literature was evaluated, as well as their influence on the formation and pre-formation of biofilms. Human blood samples A, B and O were subjected to cytotoxicity evaluation at concentrations of 250μg/mL-1000μg/mL in assays for hemolytic and antihemolytic activity. The oxidant and antioxidant activities on human hemoglobin were determined at different concentrations of the test extract. The test product presented MIC=1000µg/mL and MBC= 1300µg/mL, respectively, for Streptococcus viridans and Streptococcus pyogenes, demonstrating a bacteriostatic nature. In the association study of the extract with azithromycin against the Streptococcus viridans strain, the effect was indifferent, while in Streptococcus pyogenes the effect was antagonistic. The test extract at a concentration of 1000µg/mL prevented biofilm formation for both strains tested, but was unable to destroy pre-formed biofilm. In terms of hemolytic and anti-hemolytic activity, the product showed low activity on human erythrocytes in both tests. The green leaf extract did not show oxidizing activity. Regarding the antioxidant potential, a 65% reduction was observed compared to phenylhydrazine. The extract from the green leaves of Anacardium occidentale is safe for possible therapeutic applications, demonstrating effective antibacterial activity and low toxicological potential.