Benzyl isocyanate isolated from the leaves of <i>Psidium guajava</i> inhibits <i>Staphylococcus aureus</i> biofilm formation
Kunal Dutta, Amit Karmakar, Debarati Jana, Saroj Ballav, Sergey Shityakov, Amiya Kumar Panda, Chandradipa Ghosh
Abstract
Benzyl isocyanate (BIC), from methanol extract of Psidium guajava leaves, exhibited substantial anti-biofilm activities against Staphylococcus aureus, the common bacterial pathogen in nosocomial infections. Major components of the extract included eugenol, BIC, phenyl-2-methoxy-4-(1-propenyl)-acetate and 2,5-pyrrolidinedione,1-penta-3-4-dienyl, analyzed by GC-MS and HPLC studies. BIC exhibited substantial anti-biofilm activitiy against S. aureus, established by assaying biofilm formation, biofilm metabolic activity, bacterial adherence to hydrocarbons, exopolysaccharide formation, and optical and scanning electron microscopic studies. BIC significantly downregulated the important biofilm markers of S. aureus, viz., icaAD, sarA and agr, observed by quantitative real time polymerase chain reaction analysis. Molecular docking studies revealed thermodynamically favorable interaction of BIC with IcaA, SarA and Agr, having Gibbs energy values of −8.45, −9.09 and −10.29 kcal mol−1, respectively. BIC after binding to IcaR, the repressor of IcaA, influences its binding to target DNA site (Eshape, −157.27 kcal mol−1). The results are considered to demonstrate anti-biofilm potential of BIC against bacterial infections.