Bacteria use different types of motilities in order to colonize and adapt to new environments. These motilities also play an important role in the formation of biofilm, allowing bacteria to develop resistance to antibiotics and host’s immune systems. The objective of this study was to evaluate the ability of essential oils of Lippia multiflora flowers to inhibit biofilm formation and motility in Pseudomonas aeruginosa PAO1. The capacity of essential oil of Lippia multiflora flowers to inhibit biofilm formation in Pseudomonas aeruginosa was evaluated spectrophotometrically by using the crystal violet method. The property of the essential oil to inhibit different types of motilities such as swimming, swarming and twitching was further evaluated by measuring the diameters of bacterial migration on liquid or semi-liquid Luria Bertani agar medium. The essential oil exhibited good anti-biofilm activity in Pseudomonas aeruginosa. At a concentration of 1%, essential oil presented a degree of biofilm inhibition similar to that of salicylic acid used as a reference (P > 0.05). In addition, the essential oil significantly inhibited swarming, twitching and swimming in Pseudomonas aeruginosa compared to the control (P < 0.001). The inhibition of biofilm formation as well as that of bacterial motility increases with the concentration of the essential oil. The essential oil of Lippia multiflora flowers possesses an anti-bacterial potential to fight against multi-resistant bacteria.

Background: Infectious diseases are one of the leading causes of death worldwide because of antibiotic resistance. Ageratum conyzoides is one of the antimicrobial medicinal plants that is being used to fight various multi-resistant pathogenic bacteria in Burkina Faso. Aim: The aim was to promote safe medicinal use of A. conyzoides by highlighting the anti-biofilm and anti-motility effects of its methanol extract. Setting: The study was conducted at the Université Joseph KI-ZERBO, Ouagadougou, Burkina Faso. Methods: The antibacterial activities of methanol extract were evaluated by evaluating swimming, swarming and twitching motilities performed in an agar medium. The anti-biofilm effect was conducted in microtiter plates using the crystal violet method. The antioxidant and enzyme inhibition activities were evaluated using 2,2-diphényl-1-picrylhydrazyl; 2,2’-azino-bis (3-éthylbenzothiazoline-6-sulfonic acid), Ferric Reducing Antioxidant Power and conducting lipoxygenase test. Results: From the study, 100 µg/mL and 200 µg/mL of extract presented significant inhibition of P. aeruginosa and E. coli swarming motility but did not exhibit a significant effect on P. aeruginosa swimming and E. coli twitching motilities. The extract was effective in reducing biofilm formation in a concentration-dependent manner without affecting bacterial growth. In addition, the extract showed some capabilities to inhibit lipoxygenase activity and exhibit antioxidant potential, which could contribute to the control of oxidative stress-related diseases. Conclusion: From this study the anti-biofilm and anti-motility potential of the A. conyzoides extract provided the experimental background for the further development of antibacterial drugs. Contribution: This study provided additional scientific evidence to support the use of A. conyzoides in traditional medicine against bacterial infections.

Oral infections pose a significant global health issue. This study assessed the antibacterial properties of methanol and dichloromethane extracts from Lippia multiflora flowers against Staphylococcus aureus ATCC 43300 and Streptococcus mutans ATCC 2517, two bacteria known to cause oral infections. The study measured the ability of these flower extracts to inhibit the growth and biofilm formation of S. aureus and S. mutans using micro-dilution and crystal violet methods, respectively. Additionally, we analyzed the presence of secondary metabolites in the extracts both qualitatively and quantitatively. The antioxidant properties of the extracts were evaluated using DPPH, ABTS, and FRAP methods. The results indicated that the dichloromethane extract demonstrated a more substantial bactericidal effect than the methanolic extract against S. mutans and S. aureus, with minimal bactericidal concentrations of 0.25 ± 0.02 mg/mL and 3.13 ± 0.30 mg/mL, respectively. Furthermore, the dichloromethane extract at a 100 µg/mL concentration exhibited the highest anti-biofilm activity against both S. aureus and S. mutans. Phytochemical screening revealed the presence of alkaloids, flavonoids, quinones, and tannins in both extracts. The total phenolic content was higher in the methanolic extract (49.57 ± 2.74 mg EAG/100 mg) compared to the dichloromethane extract (25.71 ± 0.39 mg EAG/100 mg). Similarly, the total flavonoid content was more significant in the methanolic extract (2.87 ± 0.049 mg EQ/100 mg) than in the dichloromethane extract (2.24 ± 0.02 mg EQ/100 mg). The methanolic extract also exhibited superior anti-DPPH and anti-ABTS activities, as well as a higher Fe (III) reduction potential than the dichloromethane extract (P < 0.05). These findings suggest that L. multiflora flowers could serve as a potential source of antimicrobial agents for combating oral infections.