Lectins, Tannins and Antimicrobial activity in Anacardiaceae barks.

Binding capacity of lectins and tannins to bacteria cellular membrane has been associated with antimicrobial activity. Bark infusions from Schinus terebinthifolius and Anacardium occidentale, have commonly been used in popular medicine. The aim of this work was to evaluate bark extracts (E) from S. terebinthifolius (ESt) and A. occidentale (EAo) for lectin and tannin activities, as well as effects on Staphylococcus aureus and Escherichia coli growth. E were obtained in 0.15 M NaCl (ESt1 and EAo1) or 0.01 M citrate phosphate buffer, pH 4.0 (ESt2) and pH 7.0 (EAo2). E were also filtered through activated chalk (ESt1C, ESt2C, EAo1C and EAo2C). Hemagglutination activity (HA) assay used different erythrocytes and HA inhibition was performed with carbohydrates and ovalbumin. Tannin concentrations were determined using tannic acid standard curve. E were evaluated by polyacrylamide gel electrophoresis (PAGE). Antimicrobial activity was determined for E with highest specific HA and commercial antibiotics (cephalothin, nitroflurantoin and norfloxacin) using discs and puddles by the Kirby-Bauer method. The highest specific HA was obtained with rabbit erythrocytes for EAo2 (7,848). Extracts treated with activated chalk did lose HA. ESt2 and EAo2 HA were mainly inhibited by arabinose and guar gum, respectively; inhibition was also detected with ovalbumin. Tannins (mg/ml) were detected in ESt1 (1.67), ESt1C (1.58), ESt2(1.12), ESt2C (0.82), EAo1 (1.57), EAo1C (1.38) and EAo2 (1.7); tannins from EAo2C were eliminated by activated chalk treatment. PAGE revealed acidic proteins in ESt1C and ESt2C. Bark extracts inhibited S. aureus growth but did not inhibit E. coli. Antimicrobial activity was mainly detected using puddles; halos with 13.0 mm and 8.0 mm were obtained for ESt1 and EAo2, respectively. The results revealed bioactive molecules in S. terebinthifolius and A. occidentale.