Abstract
The clinical management and definitive treatment of cystic fibrosis (CF) biofilm-mediated chronic Pseudomonas aeruginosa lung infection remains a challenge. The methanol extract of the popular ethanomedicinal herb Andrographis paniculata L., which is traditionally used to treat respiratory illnesses, was shown to have growth and biofilm inhibitory activities against clinical isolates of P. aeruginosa from CF patients. Here, we report the antibiofilm activity of A. paniculata methanol extract on quorum sensing (QS) inhibition using both in vitro and molecular docking studies. The inhibitory activity of the extracts on exopolysaccharide and pigment production by the CF isolate and the QS indicator organism Chromobacterium violaceum ATCC 12472 and the interaction between the phytoconstituent, biofilm and QS proteins were determined. GC-MS analysis detected 32 plant phytochemicals of diverse nature that may account for its antibiofilm activity and its traditional use in the treatment of many illnesses, including respiratory infections. A number of compounds such as carbamic acid, N-phenyl-, 2-methylphenyl ester, and 2-methoxy-4-[(1-phenylpropan-2-ylamino) methyl] phenol, were found to possess better binding affinity (>= -5) to no less than two P. aeruginosa QS proteins without violation of Lipinski's rule. Furthermore, several compounds exhibited high drug-like molecular activity scores indicating their bioavailability and possible activity. These results indicate a significant affinity between the antibiofilm and quorum quenching activities and a probable use for the development of novel CF biofilm specific therapeutic strategies using A. paniculata extracts in the future. Moreover, the results also support the use of A. paniculata in traditional medicine.