Quorum Quenching of P. aeruginosa by Portulaca oleracea Methanolic Extract and Its Phytochemical Profile

Quorum sensing (QS) is a molecular communication mechanism among bacterial cells. It is critical in regulating virulence factors, motility, antibiotic resistance, and biofilm formation. <i>Pseudomonas aeruginosa</i> is a Gram-negative opportunistic pathogen linked to healthcare-associated infections, food poisoning, and biofilm formation. Treating infections caused by pathogenic bacteria has become a challenge due to the development of multi-antibiotic resistance upon continuous exposure of bacteria to antibiotics. An alternative strategy to conventional antimicrobials to decrease the bacterial pathogenicity is QS inhibition, also known as quorum quenching. Using plant-derived compounds is an environmentally friendly strategy to block the bacterial QS and inhibit bacterial growth. <i>Portulaca oleracea</i> is a popular plant in different countries and is also used in traditional medicine. It is widely consumed raw in salads and as garnishes, though it can be cooked as a vegetarian dish. This study evaluates the antimicrobial activity of the methanolic extract of <i>P. oleracea</i> and its effectiveness in blocking or attenuating the QS of <i>P. aeruginosa</i>. The agar well diffusion method used for screening the antibacterial activity showed a significant growth inhibition of <i>P. aeruginosa</i> by the extract at 500 mg/mL with a minimum inhibitory concentration of 31.25 mg/mL. A bioindicator bacterium, <i>Chromobacterium violaceum</i> CV026, was used to determine the effect of the methanolic extract on the QS of <i>P. aeruginosa.</i> The results indicated a significant reduction in biofilm formation, pyocyanin production, and LasA staphylolytic activity. The phytochemical analysis by Gas Chromatography-Mass Spectrometry showed that the methanolic extract contained several phenols, alkaloids, esters, and other compounds previously reported to have antibacterial and antioxidant effects. These findings highlight the effectiveness of <i>P. oleracea</i> methanolic extract in attenuating the QS and virulence factors of <i>P. aeruginosa.</i> This study suggests that <i>P. oleracea</i> is an important source of natural antimicrobials and its use would be beneficial in food and pharmaceutical applications.