Background: Due to its extensive arsenal of virulence factors and inherent resistance to antibiotics, Pseudomonas aeruginosa is a threat particularly in immunocompromised patients. Considering the central role of quorum sensing in the production of virulence factors, inhibition of bacterial communication mechanism constitute an opportunity to attenuate pathogenicity of bacteria resistant to available antibiotics. Our study aimed to assess the anti-quorum sensing activity of Anogeissus leiocarpus, traditionally used in Burkina Faso, for the treatment of infected burn wounds. Methods: Investigations were carried out on methanol extract from A. leiocarpus stem bark. The reporter strains Chromobacterium violaceum CV026 and P. aeruginosa PAO1 derivatives were used to evidence any interference with the bacterial quorum sensing and expression of related genes. P. aeruginosa PAO1 was used to measure the impact on pyocyanin production. Results: At a sub-inhibitory concentration (100 µg/mL), A. leiocarpus methanol extract quenched the quorum sensing mechanism of P. aeruginosa PAO1 by down-streaming the rhlR gene, with a subsequent reduction of pyocyanin production. Moreover, the antioxidant polyphenols evidenced are able to reduce the oxidative stress induced by pyocyanin. Conclusion: The antioxidant and anti-quorum sensing activities of A. leiocarpus stem bark could justify its traditional use in the treatment of infected burn wounds.

Aims: This current study was designated to assess the ability of Cassia occidentalis, Crossopteryx febrifuga and Zanthoxylum zanthoxyloides traditionally used for the treatment of infectious diseases, to reduce the production of virulence factors. Place and Duration of Study: The study was conducted at the Laboratory of Applied Biochemistry and Chemistry (LABIOCA), University Ouaga 1 Pr Joseph KI-ZERBO between September 2018 to January 2019. Methodology: Methanol extracts from C. occidentalis (leaves and stem), C. febrifuga (leaves and stem) and Z. zanthoxyloides (Stem bark) were used for the investigations. The reporter strain Pseudomonas aeruginosa PAO1 was used to measure the impact of extracts on elastase and pyocyanin production. Antioxidant activity was measured through 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Results: All extracts at the concentration of 100 µg/mL inhibited significantly the production of pyocyanin without affect negatively the growth of P. aeruginosa PAO1 with a reduction of 39%, 52% and 28% respectively for C. occidentalis, C. febrifuga and Z. zanthoxyloides. C. febrifuga showed the highest inhibition level on the production of elastase with a rate of 48%. The results demonstrated varying level of reduction of pyocyanin and elastase production in the reporter strain. Moreover, the antioxidant polyphenols evidenced are capable to reduce the oxidative stress induced by pyocyanin. Conclusion: The antioxidant and anti-virulence properties of these medicinal plants could justify their traditional use in the treatment of infectious diseases.

Aims: The study aims to assess the ability of Acacia dudgeoni bark to antagonize quorum sensing system, expression of virulence factor and biofilm formation. Place and Duration of Study: The study was conducted at the Laboratory of Applied Biochemistry and Chemistry (LABIOCA), University Joseph KI-ZERBO between December 2018 to April 2019. Methodology: Methanol extract from A. dudgeoni stem bark, was used for the investigations. The reporters strain Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PAO1 were used to measure the impact of extract on quorum sensing controlled violacein and pyocyanin production. P. aeruginosa PAO1 was used to measure the impact on biofilm formation. Results: At different concentrations (50-400 µg/mL) A. dudgeoni methanol extract quenched the quorum sensing mechanism. Significant inhibition of virulence factor, pyocyanin was recorded (66% of inhibition at 400 µg/mL) without affect negatively the growth of P. aeruginosa PAO1. The formation of biofilm was also affected with a reduction up to 59% at the concentration of 400 µg/mL. Conclusion: The anti-quorum sensing and anti-biofilm properties of this medicinal plant could serve as a source in the developpement of new effective anti- quorum sensing drugs.