Antimicrobial, anti-biofilm and anti-quorum sensing compounds from the bark of Ekebergia capensis

Abstract

The main objective of this study was to isolate bioactive compounds from Ekebergia capensis for antimicrobial, anti-biofilm and anti-quorum sensing activity. The bark of E. capensis was extracted using hexane, ethyl acetate and methanol for 72 hours on maceration at room temperature. Antibacterial activity was evaluated against Staphylococcus aureus and antifungal activity against Candida albicans at 5 and 10 mg/mL concentrations. Anti-biofilm activity was tested using test tube and swarming motility test methods and anti-quorum sensing was evaluated using flask incubation test for violacein inhibition production methods. The results showed ethyl acetate extract of E. capensis and its two isolated compounds exhibited antimicrobial, anti-biofilm and anti-quorum sensing activity. Inhibition zones of antimicrobial activities of the extract against S. aureus and C. albicans ranged between 4-20 mm. 10 mg/mL extract showed inhibition of biofilm formation against S. aureus, anti-swarming activities against P. aeruginosa and S. aureus. Inhibition of violacein production against S. aureus, P. aeruginosa, and C. albicans were 72.6%, 67.7% and 69.3% respectively. The ethyl acetate extract, which showed antimicrobials, anti-biofilm, anti-quorum sensing activities, after silica gel column chromatography furnished two compounds namely; diisobutylphtalate and Sandropin B. The chemical structures of these compounds were done using spectroscopic methods including IR and NMR. The isolated compounds also showed strong antimicrobial, anti-biofilm, and anti-quorum sensing activity. This could be useful to manage infectious diseases caused by biofilm forming microorganisms.