Search

Background: Chromobacterium violaceum (C. violaceum), a Gram-negative, facultative anaerobic, non-sporing coccobacillus has a quorum-sensing system consisting of CviI/CviR, a homologous gene. Quorum sensing (QS) is a mechanism of intercellular communication in bacteria that received substantial attention as an alternate strategy for combating bacterial resistance and the development of new anti-infective agents. Methods: DATA SET Information of photochemical from the natural source deposited as a machine readable format in PubChem database was utilized to retrieve the compound for the study. To study ligand - receptor interactions, docking paves way to accomplish the protein ligand interaction was docked through rigid docking CviR protein (PDB ID: 3QP5) was prepared and energy minimized to evaluate the best affinity among the complex. Results: The results showed that the Alpha.,2.Alpha.- Epoxy-1.Beta.- Methyl Cholesta-4,6- Dien-3-One had high affinity for CviR receptor protein and Alpha.,2.Alpha.- Epoxy-1.Beta.- Methyl Cholesta-4,6- Dien-3-One binds to the active site of CviR with binding energy of -9.6 kcal/mol. Conclusion: Overall study concluded that 1. Alpha., 2. Alpha.- Epoxy-1.Beta.-Methyl Cholesta-4,6-Dien-3-One with highest binding affinity for the CviR protein possessing strong inhibitory binding interaction. Hence, we concluded that 1.Alpha.,2.Alpha.-Epoxy-1.Beta.- Methyl Cholesta-4, 6-Dien-3-One good serves as potential an anti-quorum sensing molecule for treating C. violaceum infection.

Background: Pseudomonas aeruginosa is a Gram-negative opportunistic human pathogen that mainly infects immunocompromised individuals and patients with urinary tract infection and chronic infections of the respiratory pathways, including cystic fibrosis. Many quorum sensing (QS) controlled components such as bio surfactants and swarming motilities play an important role in the establishment of biofilms. Targeting these factors through anti-QS strategies prevent biofilm formation and treating infections. Coccinia indica commonly called little gourd is used to treat diabetes, wound, burn infections and has antioxidant, antibacterial and antitussive properties. Methods: The methanolic fruit extract of C. indica was prepared and screened for anti-QS and anti-biofilm formation activity. Pyocyanin inhibition, rhamnolipid, crystal violet staining assay tests was performed and the extract was observed under fluorescent microscope. Results: The results obtained are as follows - the fruit extract inhibits the pyocyanin at 58.13% and 42.27% at 0.5 mg/ml and 1.0 mg/ml, biofilm at 69.86% and 49.06% at 0.5 mg/ml and 1.0 mg/ml, inhibits rhamnolipid assay and under fluorescent microscope it is seen scattered whereas control produce biofilm matrix like appearance. Conclusion: Since less study has been made on the quorum sensing and biofilm activity of C.indica our study aimed to fulfil it and it was found that it exhibits good biofilm formation and thus can be used for treating infections.

Pseudomonas aeruginosa use small signaling molecules such as acyl homoserine lactones (AHLs), which play an important role in release virulence factors and toxin for further establishment of host infection. Thus, involving with the QS system would provide alternative ways of preventing the pathogenicity. In the present study, totally six medicinal plants (Terminalia bellerica, Celastrus paniculatus, Kingiodendron pinnatum, Schleichera oleosa, Melastoma malabathricum, Garcinia gummi-gutta) were screened for anti-QS activity using biomonitor strain of Chromobacterium violaceum CV12472. The primary screening of antimicrobial activity of all the plant extracts have inhibited the growth of tested bacterial species. Of these at the sub-minimum inhibitory concentration the methanol extract of T. bellerica (0.0625–0.5 mg/ml) has significantly inhibited violacein production (20.07–66.22%) in C. violaceum (CV12472). Consequently, the extract of T. bellerica has reduced the production of pyocyanin, exopolysaccharide and biofilm formation in P. aeruginosa strains. Fluorescence and scanning electron microscopy analysis confirmed the reduction of biofilm formation in P. aeruginosa strains when treated with T. bellerica. GC–MS analysis showed the active compounds inhibited the production of virulence factors of P. aeruginosa. The results suggest the possible use of this T. bellerica as an anti-QS and anti-biofilm agent to control Pseudomonas infection. Interference of QS provides an important means for the inhibition of bacterial virulence and thus aids in treatment strategies., Graphical abstract Image 1

Pathogenic Pseudomonas species produce virulence elements and form biofilm through quorum sensing (QS) system. Clinical infections caused by Pseudomonas aeruginosa are becoming increasingly tough to treat on account of wide spread drug resistance. The drugs have lost their efficacy due to the virulence elements and biofilms, which are responsible for increased severity of the infection. The search for novel drugs has increased and novel modes of action against Gram-negative pathogenic bacteria are been much more of important. Plants secondary metabolites are widely used for treating the many bacterial diseases. Plant-derived anti-QS and anti-biofilm compounds that do not negatively affect the growth of the bacterial cells, but rather attenuates the QS controlled virulence factors, that might allow the host defense to act more effectively to washout the P. aeruginosa infection. In this review mainly focus on overview of pathogenicity, QS controlled virulence factors and biofilm formation of P. aeruginosa infection. This review describes a brief account of QS inhibitors and anti-biofilm compounds, which exhibit alternative medicine possible for treating drug resistant P. aeruginosa.

The global emergence of antibiotic-resistant strains of Pseudomonas aeruginosa poses a major threat in both hospital environments and the community. P. aeruginosa is an opportunistic human pathogen, and it also infects a wide range of model organisms including the nematode Caenorhabditis elegans. Quorum sensing (QS) mediates cell-to-cell communication in bacteria and has an important role in regulating virulence genes, antibiotic resistance and biofilm formation, which are crucial for establishment of the infection. Expression of many virulence factors such as pyocyanin and proteases in P. aeruginosa is under the control of the QS system, and are mediated by small molecules such as acyl homoserine lactones. Thus, interfering with the QS system would provide alternative ways of controlling the pathogenicity. Murraya koenigii is a medicinal plant widely used in India. The present study investigated the in vivo inhibitory activity of M. koenigii essential oil (EO) on QS-controlled virulence factors of P. aeruginosa PAO1 using C. elegans. M. koenigii EO significantly inhibited the pyocyanin production and staphylolytic LasA activity of P. aeruginosa PAO1. As compared to the control group with 100 % killing of C. elegans, M. koenigii EO was able to rescue an average of 60 % of C. elegans from death due to the toxic effect of P. aeruginosa. Thus, the present study suggests the anti-QS potential of M. koenigii EO which therefore can be considered as a future therapeutic agent for management of P. aeruginosa-mediated infections.