Novel derivatives of plant monomeric phenolics: act as inhibitors of bacterial cell-to-cell communication

The aim of the present study was to synthesize novel active Anti-Quorum sensing derivatives from secondary metabolites viz. Gallic acid, Protocatechuic acid and Vanillic acid present in the plant Bergenia ciliata. Efficacy of all synthesized derivatives have been evaluated on the formation of bacterial biofilm and inhibition of cell-to-cell communication. Anti-Quorum Sensing activity and biofilm formation of all synthesized compounds was measured on biomonitor strain Chrobacterium violaceum, ATCC 12472 using standard paper disk-diffusion assay and quantification of violacein pigment. Among all derivatives, five derivatives 3,4,5-Trihydroxy-benzoic acid methyl ester (9a), 3,4-Dihydroxy-benzoic acid methyl ester (10a), 3,4,5-Tris-(2,4-dichloro-benzyloxy)-benzoic acid methyl ester (12), 3,4,5-Tris-(2,5-dichloro-benzyloxy)-benzoic acid methyl ester (13) and 4-(2,4-Dichloro-benzyloxy)-3-methoxy-benzoic acid methyl ester (15) has shown Anti-Quorum Sensing activity by inhibiting violacein pigment production and biofilm formation without interfering with its growth. The inhibitory effects in violacein pigment production were: positive control (C-30) 72%, (9a), (10a) 47.2%, (12) 27.3%, (13) 40.1% and (15) 22.7% at the concentration of 1 mg/mL and biofilm percent inhibition were found (C-30) 64% (9a) 46.2%, (10a) 40.3%, (12) 18.4%, (13) 35.2%, and (15) 17.3% when compared with the untreated control. Results reveal that synthesized derivatives seem to be good compounds for inhibition and formation of biofilm and AHL-mediated Quorum-sensing mechanism. The present article highlights the importance of derivatives derived from secondary metabolites as potent drug for biofilm formation and inhibition of cell-to-cell communication.