Piper betle Leaf Extract Exhibits Anti-virulence Properties by Downregulating Rhamnolipid Gene Expression (rhlC) of Pseudomonas aeruginosa

BACKGROUND: Piper betle (P. betle) is widely used as a traditional medicine in Indonesia, with anti-quorum sensing and anti-biofilm activity. We investigated the impact of methanolic leaf extract of P. betle against Pseudomonas aeruginosa’s (P. aeruginosa) virulence factor, which associated with rhamnolipid (rhl) genes, METHODS: Minimum biofilm inhibitory concentration of the extract was determined at a concentration of 0.4% by agar dilution assay. The expression of rhlA and rhlC gene was assessed by using real-time polymerase chain reaction. RESULTS: All P. aeruginosa isolates contained rhlA, rhlB, and rhlC genes, which associated with rhl production. The expression of the rhlC gene decreased after administration of P. betle leaf extract at concentration of 0.4%, with beta coefficient was 0.662 (p = 0.019). CONCLUSION: The methanolic leaf extract of P. betle shows inhibition of rhlC gene expression, indicating the anti-rhl properties of P. betle against P. aeruginosa infection.