Anti-Quorum Sensing Activity of Tetracera scandens and Aleurites moluccana Leaf Extracts against Chromobacterium violaceum

Aims: To test the efficacy of Tetracera scandens (L.) Merr. and Aleurites moluccana (L.) Wiild. methanolic leaf extracts on the inhibition of quorum sensing-dependent pigmentation of Chromobacterium violaceum.

Study design: In-vitro quorum sensing inhibition design was conducted.

Place and Duration of Study: The study was conducted at the Biology Laboratory, College of Science, Pamantasan ng Lungsod ng Maynila between November 2015 to May 2016.

Methodology: The leaf extracts were obtained through soaking in methanol and subsequent rotary evaporation. Qualitative screening of the anti-quorum sensing activities of the extracts were done through Agar Well Diffusion Assay. The Minimum Quorum Sensing Inhibition Concentration was determined through two-fold serial dilution and then wells were streaked on Mueller-Hinton Agar plates to identify the Minimum Bactericidal Concentration. Disc Diffusion Assay was done to quantitatively measure the anti-quorum sensing activities of the leaf extracts.

Results: The crude methanolic leaf extracts of T. scandens and A. moluccana were able to inhibit quorum-sensing on C. violaceum. The anti-QS activities of both plants were comparable at their Minimum Quorum Sensing Inhibitory Concentrations (P>.05), however, weaker activities were observed against the positive control (P = 0.001). The two extracts were partially active in inhibiting quorum sensing but were inactive in growth inhibition.

Conclusion: This study revealed that T. scandens and A. moluccana exhibit anti-quorum sensing activities against C. violaceum and these may be due to their phytochemical constituents, including flavonoids, terpenoids, and phenolics, which were previously proven to exhibit anti-quorum sensing activity. Extensive studies on the isolation of these compounds which may be responsible for their activities may be required to further improve the efficacy and harness the potential of these plants on quorum sensing inhibition.