Table 1.

IC₅₀ (antagonists) or EC₅₀ (agonists) values for compounds in Figure 6 against three bacterial strains. All values reported in µM. A blank entry indicates the value was not determined.

Compound	P. aeruginosa LasRa,d	A. tumefaciens TraRb	V. fischeri LuxRc,e
Antagonists
3-oxo-C8-HSL	0.11
C10-HSL	0.25	1.05	0.40
27	0.34	0.92	1.35
28	1.72	1.25	0.86
C8-HSL	1.75	0.77	0.77
30	4.67	0.46
4		0.69	1.36
29		0.81	0.61
Agonists
3-oxo-C14-HSL	0.01
C12-HSL	0.04
32	0.54
31

^aAntagonism assay performed using an E. coli LasR reporter strain in the presence of 7.5 nM 3-oxo-C₁₂-HSL.

^bAntagonism assay performed using A. tumefaciens reporter strain in the presence of 100 nM 3-oxo-C₈-HSL.

^cAntagonism assay performed using V. fischeri reporter strain in the presence of 5 µM 3-oxo-C₆-HSL.

^d,eAgonism assays performed using the appropriate reporter strain in the absence of natural autoinducer.