Inhibition of pyocyanin production in pseudomonas aeruginosa by natural antimicrobial compounds from herbal extracts

Abstract

Objective: Pseudomonas aeruginosa produces a range of metabolites including pyocyanin that enhance its ability to resist antibiotics and becomes capable of surviving adverse conditions. Methods: In this report, eight plants (extracted with five solvents) were screened for antibacterial activity against P. aeruginosa by microbroth dilution method. Afterward tested for inhibition of pyocyanin in presence and absence of plant extracts. Result: Among these Digera muricata and Solanum quitoense exhibited good antibacterial potential. Inhibition of pyocyanin is identified as a potential anti-virulence strategy. Therefore, acetone extract of six plants exhibited minimum inhibitory concentration (MIC) ≤3.125 mg/ml and methanol extract of three plants exhibited MIC ≤6.25 mg/ml was used to check pyocyanin inhibition in P. aeruginosa. In acetone extracts, significant pyocyanin inhibition was found in Ipomoea pesticides and Citrullus colocynthis. In methanol extracts, C. colocynthis and D. muricata showed considerable pyocyanin inhibition. Conclusion: Overall result indicates that the best antimicrobial compound (growth inhibitor) may not be best inhibitor of pyocyanin biosynthesis or vice-versa. Moreover, I. pesticides, C. colocynthis, and D. muricata seem to contain compounds which inhibit the growth of bacteria as well as the biosynthesis of pyocyanin.