Baicalein is a flavonoid compound originally isolated from the roots of Scutellaria baicalensis (Fig. 23C).204 Recently, it has been shown to inhibit DMS3vir phage infection in Pseudomonas aeruginosa through phage adsorption inhibition.205 DMS3vir phage requires the type IV pilus of P. aeruginosa as its receptor,206,207 which is regulated by quorum sensing systems.208 The authors proposed that the inhibited phage adsorption was due to the down-regulation of type IV pilus through the inhibition of quorum sensing caused by baicalein.205. This evidence concerns the gene SGCG and infection.