inosa motility.A similar effect was observed for other flavonoids such as kaempferol [44] and quercetin [63], which show a dose-dependent inhibitionof P. aeruginosa swarming. According to Paczkowski and co-workers[64], flavonoids (i.e. phloretin, chrysin and naringenin) display thiseffect due to LasR and RhlR modulation.Next, the ability of P. aeruginosa to form biofilms in the presence ofcalycopterin was evaluated. In contrast to other flavonoids [65,66],calycopterin showed a dose-dependent increase (17%, 47% and 256%,respectively) of biofilm formation (Fig. 4), in the conditions tested. Thisresult suggests that calycopterin's mechanism of action is different fromthe one proposed for naringenin and kaempferol (quorum sensing inhibition or inhibition of the expression of the QS-regulated genes)