Table 1. Comparison of AHL octanol/water partition coefficients.

QS molecule	Projected LogP (±0.49)
3-oxo-C14-HSL	3.25
3-oxo-C13 HSL	2.74
3-oxo-C12-HSL	2.23
3-oxo-C11-HSL	1.72
3-oxo-C10-HSL	1.21
3-oxo-C8-HSL	0.19
COOH-3-oxo-C12-HSL	0.18

Comparison of AHL octanol/water partition coefficients (LogP) values calculated from molecular structure using ACD/I-Lab LogP algorithm 12.0. Lipophilicity is observed to significantly increase as AHL chain length increases from C8 to C14 (r = 1.000, p<0.01, Spearman correlation). Addition of a carboxylic acid group to the 3-oxo-C12 HSL acyl chain results in a marked reduction in projected LogP. This compound was therefore expected to interact with membranes to a lesser degree than the major AHL released by P. aeruginosa 3-oxo-C12 HSL. LogP±95% confidence interval shown.