GC-MS identification of bactericidal and antibiofilm compounds from the essential oils of Lippia multiflora Moldenke (Verbeaceae) flowers: a promising study to combat bacterial resistance

Background: Bacterial resistance to conventional antibiotic therapy has become a global health crisis. Bacterial biofilm formation allows bacteria to develop resistance to antibiotics and the host immune system. This study aims to contribute for fighting against bacterial resistance through the inhibition of bacterial biofilm formation by Lippia multiflora flowers essential oils. Methodology: The sensitivity of Staphylococcus aureus and Streptococcus mutans to the essential oils was measured on the Luria Bertani-Agar mediumby using the antibiotic susceptibility test. The anti-biofilm potential of the essential oil was evaluated by t he crystal violet method. The antioxidant potential of the essential oils was assessed by the DPPH method. The phytochemical profile was determined by gas chromatography-mass spectrometry (GC/MS) analysis. Results: The essential oils showed higher growth inhibition diameters of S. aureus (28.38±0.23 mm) and S. mutans (24.5±0.25 mm) than reference antibiotics such as gentamicin 30 mg (13.5 ± 0.07 mm on S. aureus ) and Oleandomycin 10μg (16.5 ± 0.05 mm on S. mutans ).The essential oil was also more active in inhibiting biofilm formation than salicylic acid with inhibition percentages ranged from 60 ± 0.00% on S. aureus and 71.60 ± 0.70% on S. mutans . Moreover, the essential oils exhibited good antioxidant activity with anti-DPPH inhibitory concentration ranged from 0.23 ± 0.02 µg/ùL. GC-MS analysis of the essential oils led to the identification of 22 terpens compounds with 7 major compounds such as β-caryophyllene (43.55%), germacrene D (16.44%), elemol (10.33%), eucalyptol (6.41%), humulene (3.28%), α-phellandrene (2.68%) and β-ocimene (2.62%). Conclusion: These results showed that the essential oils of L. multiflora flowers are a promising candidate in the fight against bacterial resistance.