ANALYSIS OF QUORUM QUENCHING POTENTIAL OF EUPHORBIA TRIGONA MILL.

S. marcescens and P. mirabilis are gram-negative bacteria responsible for nosocomial infections. Quorum sensing regulates virulence in S. marcescens and P. mirabilis. Present study documents the potential of E. trigona extracts in inhibiting quorum sensing in both the bacterial species. Extracts of aerial part of the plant were prepared in petroleum ether, chloroform, ethyl acetate, acetone and methanol using soxhlet extraction technique. Petroleum ether extract, chloroform extract, and acetone extract were found to quench quorum in S. marcescens. These extracts were next subjected to column chromatography and assayed for its quorum quenching capacity. Later, thin layer chromatography was used to separate and identify the bioactive fraction responsible for quorum quenching. The fraction exhibiting quorum quenching capacity was subjected to GC-MS analysis. It revealed the presence of fatty acid derivatives in the bioactive fraction. A major part of the bioactive fraction was 9,12-Octadecadienoyl chloride (Z, Z), a derivative of linoleic acid, and, hence linoleic acid was also used for testing its effect on swarm motility of bacteria. Furthermore, the bioactive fraction was employed to study the inhibition of virulence factors in S. marcescens and P. mirabilis. Bioactive fraction lowered the prodigiosin production as well as reduced swarming motility and biofilm formation in S. marcescens. It was also found effective in decreasing urease synthesis, biofilm formation and swarming in P. mirabilis. Therefore, bioactive fraction isolated from E. trigona and linoleic acid both quenched quorum in S. marcescens and P. mirabilis.