Antimicrobial, Antibiofilm Activities and Synergic Effect of Triterpene 3ß,6ß,16ß-trihydroxyilup-20(29)-ene Isolated from Combretum leprosum Leaves Against Staphylococcus Strains.

Antimicrobial resistance is a natural phenomenon and is becoming a huge global public health problem, since some microorganisms not respond to the treatment of several classes of antibiotics. The objective of the present study was to evaluate the antibacterial, antibiofilm, and synergistic effect of triterpene 3ß,6ß,16ß-trihydroxyilup-20(29)-ene (CLF1) against Staphylococcus aureus and Staphylococcus epidermidis strains. Bacterial susceptibility to CLF1 was evaluated by minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assay. In addition, the effect combined with antibiotics (ampicillin and tetracycline) was verified by the checkerboard method. The biofilms susceptibility was assessed by enumeration of colony-forming units (CFUs) and quantification of total biomass by crystal violet staining. The compound showed bacteriostatic and bactericidal activity against all Staphylococcal strains tested. The synergistic effect with ampicillin was observed only for S. epidermidis strains. Moreover, CLF1 significantly inhibited the biofilm formation and disrupted preformed biofilm of the all strains. Scanning electron microscopy (SEM) images showed changes in the cell morphology and structure of S. aureus ATCC 700698 biofilms (a methicillin-resistant S. aureus strain). Molecular docking simulations showed that CLF1 has a more favorable interaction energy than the antibiotic ampicillin on penicillin-binding protein (PBP) 2a of MRSA, coupled in different regions of the protein. Based on the results obtained, CLF1 proved to be a promising antimicrobial compound against Staphylococcus biofilms.

Purification, partial characterization and immobilization of a mannose-specific lectin from seeds of Dioclea lasiophylla mart.

Lectin from the seeds of Dioclea lasiophylla (DlyL) was purified in a single step by affinity chromatography on a Sephadex® G-50 column. DlyL strongly agglutinated rabbit erythrocytes and was inhibited by monosaccharides (D-mannose and α-methyl-D-mannoside) and glycoproteins (ovalbumin and fetuin). Similar to other Diocleinae lectins, DlyL has three chains, α, ß and γ, with mass of 25,569 ± 2, 12,998 ± 1 and 12,588 ± 1 Da, respectively, and has no disulfide bonds. The hemagglutinating activity of DlyL was optimal in pH 8.0, stable at a temperature of 70 °C and decreased in EDTA solution, indicating that lectin activity is dependent on divalent metals. DlyL exhibited low toxicity on Artemia sp. nauplii, but this effect was dependent on the concentration of lectin in solution. DlyL immobilized on cyanogen bromide-activated Sepharose® 4B bound 0.917 mg of ovalbumin per cycle, showing the ability to become a tool for glycoproteomics studies.