| Bacterial quorum sensing is a process that enables bacteria to communicate using secreted signaling molecules called autoinducers. Previous researches showed QS controlled bioluminescence, secretion of virulence factors, biofilm formation, etc. Quorum-sensing inhibitors (QSIs) have important effect as a kind of new antibiotics on the treatment of bacterial infections, which could inhibit the formation of biofilm, reduce the virulence factor expression and improve the drug sensitivity. Chinese herbal medicines are used as traditional unique drugs to prevent and cure the diseases, which also is an important symbol of Chinese medicine different from other medical. Chinese herbal medicines as a kind of extensive source have some medicinal health care values, so they are good raw materials for looking for a new way to treat bacterial infections. Based on this, QS inhibitors from more than ten kinds of Chinese herbal medicine were extracted using75%methanol. And the reported bacteria C. violaceum CV026was employed to evaluate the QS inhibition activity using plate assay and the test tube experiments. Ultimately, eight crude extracts could control the production of violacein pigment and exhibit QS inhibition activity. In addition, these crude extracts could also inhibit population swarmming and migration phenomenon of Pseudomonas aeruginosa. Furthermore, in this research, we constructed an expression vector for expression of the RhIR gene (the receptor protein of quorum sensing signal molecules) to explore the mechanism of the QS inhibition. The results suggested that those crude extracts have no effect on the stability of the RhIR receptor protein, which suggested that these crude extracts probably competed with signal molecules to realize the quorum sensing inhibitory activity. The above experimental results indicated that screening quorum-sensing inhibitors from Chinese herbal medicine is completely feasible, which provides more wide raw materials. |
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