| The emergency of multi-resistant bacteria due to indiscriminant use of antibiotic led to the search for new antibacterial approaches, for new classes of compounds that are not affected by resistance mechanisms already present in the bacterial. Quorum sensing (QS) or cell to cell communication is a cell-density dependent bacterial response mediated by hormone-like compounds called autoinducers. QS-dependent regulation of gene expression controls a wide variety of prokaryotic phenotypes including biofilm formation, virulence factor expression, and motility. Therefore the inhibition of QS is considered as a new approach of antimicrobial chemotherapy as anti-QS compounds target genes that are essential for basic metabolism in vitro, rather than the microorganisms itself. This study initiates a directed search for QS inhibiting agents in Traditional Chinese Medicinal Herbs. 2medicinal herbs were screened for anti-QS activity using two biomonitor strains, Chromobacterium violaceum and Agrobacterium tumefaciens. Of these plants, two showed QS inhibition: Galla chinensis and Coptis chinensis. These plants showed both strong QSI activity with Chromobacterium violaceum and inhibited violaceum production by CV026 at dose grade. Coptis chinensis did not affect QS mediated-galactosidase expression in Agrobacterium A136, suggesting a narrow range of QSI activity while Galla chinensis showed a strong activity and thereby wider range of QSI activity. These plants were further examined for their effects on the QS-Regulated virulence factors namely; swarming motility and biofilm formation of model strains Pseudomonas aeruginosa opportunistic pathogens responsible for, morbidity and mortality in the immunocompromised patient and Eschen'chia coli. Galla chinensis and Coptis chinensis were found to significantly inhibit swarming motility of PAOI and E. coli at grade dose. Galla chinensis inhibited 84% and 90% swarming mortility of PAOI and E. coli respectively whereas Coptis chinensis inhibited 73% and 63% respectively at 100g/mL. The thickness of PAOI biofilm was reduced by 37% by Coptis chinensis but was wickedly affected (23%) by Galla chinensis extracts at the concentration of 200g/mL. Furthermore we developed a fast QSI screening system; using a Cell free lysate of the strain Agrobacterium tuMefaciens A136 based on P-galactosidase activity. Typically, an assay with a whole-cell bioreporter such as A. tumefaciens A136 requires 16 to 18 h to culture the bioreporter strain and an additional 16 to 18H for incubation of the assay mixture to detect QSI compounds. In contrast, our QSI screening system takes 1 to 2h in total. Therefore, the cell-free assay system for detecting QSI compounds eliminates the time-consuming cell conditioning step in biosensor cell cultures that is required before each whole-cell bioassay.Activity guided fractionation, identification using Reversed-phase HPLC coupled with the new QSI selector system led to the identification of Pentagalloylglucose, a gallotanin precursor as one of the active QSI compound from Galla chinesis. Moreover this compound as a prototype of Chinese gallotannins, showed the same extent of antipathogenic activity as Galla chinensis in Pseudomonas aeruginosa PAO1 swarm plate. When we co-cultured PAO1 in presence of 5; 10 and 25 ug/mL of Pentagalloylglucose, the virulence factor pyocyanin, pigment production was strongly repressed by 27.95 ; 42.25; 58.53% respectively.This study introduces 2 new anti quorum sensing plants from China possessing a great antipathogenic activity. Targeting the QS system, instead of killing bacteria, provide a solution to antibiotic resistance. The result of this study may open a new area of research on mechanistic activity of traditional Chinese medicinal plant and potentially give a new therapeutic direction for the treatment of bacterial infections.In addition, this is the first report of Pentagallolglucose, pure compound isolated from Galla chinensis, having a revealed inhibition on the QS system and QS-Regulated virulence factors. And the least this is the first report of the time-saving QSI selector system based on free cell lysate to screen and compare QSI compounds.In addition, this is the first report of Pentagallolglucose, pure compound isolated from Galla chinensis, having a revealed inhibition on the QS system and QS-Regulated virulence factors. And the least this is the first report of the time-saving QSI selector system based on free cell lysate to screen and compare QSI compounds.
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