Benzyl isocyanate isolated from the leaves of Psidium guajava inhibits Staphylococcus aureus biofilm formation

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 (E_shape, −157.27 kcal mol⁻¹). The results are considered to demonstrate anti-biofilm potential of BIC against bacterial infections.

Keywords:

• Staphylococcus aureus
• Psidium guajava
• GC-MS
• BIC
• anti-biofilm
• molecular docking

Acknowledgements

Prof. Ajay Kumar Misra, Director, USIC, Vidyasagar University, India is sincerely acknowledged for the SEM studies.

Disclosure statement

The authors declare no conflict of interest.

Compliance with ethics requirements

This article does not contain any studies with human or animal subjects.

Additional information

Funding

The Indian Council of Medical Research (ICMR), Govt. of India, New Delhi, India in the form of a research grant is sincerely acknowledged by CG (No. 5/8-1 (189)/TF/2011-12 ECD). KD acknowledges the Council of Scientific and Industrial Research (CSIR), Govt. of India, New Delhi, India for a Senior Research Fellowship (SRF) sanction letter no. 09/599(0082)/2019-EMR-I dated: 29/03/2019. AKP sincerely acknowledges the Department of Biotechnology, Ministry of Science and Technology, Govt. of India for a research project (No: BT/PR3802/BRB/10/981/2011).