Effect of isolimonic acid on AI-3/epinephrine mediated signaling. Inhibition of preconditioned media induced β-galactosidase activity in (A) TEVS232 (LEE1) and (B) TEVS21 (LEE2) by 100 μg/ml isolimonic acid or DMSO (control). Preconditioned media was prepared as described in text. (C) Epinephrine induced β-galactosidase activity in TEVS232 in presence of 100 μg/ml isolimonic acid or solvent control (DMSO). The EHEC was grown to OD600 ≈ 0.2, collected by centrifugation and resuspended in preconditioned medium or media supplemented with 50 μM epinephrine. Isolimonic acid or DMSO were added and β-galactosidase activity was measured after 30 min incubation. Asterisk denotes significant (p<0.05) difference from solvent control (DMSO).