Effect of Bromination on Quorum Sensing Inhibition of Indole Carboxaldehydes

Abstract

Quorum sensing is a form of bacterial communication that regulates group behaviors such as biofilm formation and production of virulence factors. As a result, inhibition of quorum sensing may prevent activation of pathogenesis in a number of bacterial species. Indoles are a type of signaling molecule found in many bacterial species and the indole derivative indole-3-carboxaldehyde has been found to inhibit quorum sensing mediated behaviors in Escherichia coli. Bromination may be a way to increase quorum sensing inhibiting properties of indole carboxaldehydes. The IC50s of three monobrominated indole carboxaldehydes were determined and compared to the IC50 of indole-3- carboxaldehye. IC50s of all three test compounds were significantly decreased from the control. There was not a significant difference between different bromination patterns, although two compounds showed a trend towards a reduced IC50 when compared to the third compound.