Studies Of QSI-based Phytochemicals In L.Chinense (Hemsl.) Sarg. X L.Tulipifera L.

This paper studied bacterial quorum sensing inhibiting based phytochemicals in L.chinense (Hemsl.) Sarg. x Ltulipifera L. The pharmaceutical values of Liriodendron tulipifera have been studied well, but Liriodendron chinense and L.chinense (Hemsl.) Sarg. x Ltulipifera L showed less investigating. Quorum sensing is a phenomenon that bacteria release chemical signals and induce the expression of virulence genes as the density of pathgenic/nonpathgenic bacteria reach a threshhold. Nowadays, the abuse of antibiotics led to the emergence of multidrug-resistant bacteria and threaten human life. Quorum sensing inhibitor (QSIs) can indirectly control the expression of pathogen virulence genes, and maybe give one method to solve these problems.The model of screening for quorum sensing inhibitors was established here, and chemicals were screened, fortunatedly, Resveratrol and DCE (Liriodendron hybrid in dichloromethane crude extract part) showed QSI activities. Next, we continued to invesigate the DCE part in Liriodendron hybrid.10phytochmeicals were isolated and putified, by polyseparating methods (chiral sepearation included),6phytochemcials were elucidated by NMR,2D-NMR and MS spectrum, they are:(+)-pinoresinol(â… ), syringaresinol(â…¡), R-lirihydin (III), S-lirihydin (IV), sitosterol(V), hexadecanoic acid (V), and2,2-dihydroxyproxypropyl ester(VI). All these chemicals showed no QSI activities.