Antibacterial synergism of extracts from climbers belonging to Bignoniaceae family and commercial antibiotics against multi-resistant bacteria

- Synergism of all extracts with antibiotics was demonstrated.
- The F. caudigera extract was the best in enhancing the effect of oxacillin.
- This combination inhibited to methicillin resistant S. aureus (MRSA) strains.
- Apigenin, chrysin and luteolin were identified in the extract of F. caudigera.
- MIC values were between 62.5-250 μg/mL. Luteolin was active against MRSA strains.

The objective of this work was to study the effect of interactions between four extracts of climbers belonging to the Bignoniaceae family and commercial antibiotics against multi-resistant pathogenic bacteria and to identify the main antibacterial compounds in the most active extract. The plant species tested were Adenocalymma marginatum, Amphilophium vauthieri, Cuspidaria convoluta and Fridericia caudigera. Synergy between the plant extracts with ampicillin, gentamicin and oxacillin was studied by the checkerboard assay method against multi-resistant Staphylococcus strains and Gram negative bacteria. A synergistic effect was observed in all extracts. The F. caudigera leaf extracts were most active. The main antibacterial compounds present in these extracts were isolated and identified by UV-VIS spectra and HPLC/MS/MS. Three main active compounds were identified, apigenin, chrysin and luteolin. Our results indicated that the combinations of species extracts of Bignoniaceae family and commercial antibiotics could be useful in the treatment of many infectious diseases caused by multi-resistant bacteria. In addition, the results highlighted the potential phyto-therapeutic of a total set of phytochemical compounds within a single plant.

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