Inhibitory Activity of β-lactamases by Hydro-Ethanolic Extracts of Harungana madagascariensis, a Plant of the Ivorian Pharmacopoeia

Infection due to multi-resistant bacteria is a public health concern. Unfortunately, the prospect of developing new antibiotics seem not to be on the horizon. Faced with this impasse, medicinal plants could be an alternative for the development of new molecules. The aim of this study was to determine the inhibitory effect of H. madagascariensis extracts on β-lactamases. Extraction of bioactive compounds from trunk barks and leaves of the plant was done in an ethanol-water mixture (70:30). Anti-β-lactamase activity was evaluated by spectrophotometry after the removal of tannins and a phytochemical screening was used to identify the groups of compounds. Concentrations inhibiting 50% of enzyme activity were 0.005±0.001 mg/mL (CTX-M-15), 0.01±0.001 mg/mL (P99) and 0.027±0.009 mg/mL (NDM-1) for bark extracts and 0.704 mg/mL for leaves extracts. Phytochemical screening revealed the presence of flavonoids in bark extracts. The ethanolic extracts of the trunk bark exert a good inhibitory activity on CTX-M-15, P99 and NDM-1 β-lactamases and this activity could be attributed to the presence of the flavonoids. Further studies by bio-guided fractionation of the ethanolic extracts of the bark could yield fractions with high inhibitory potential of β-lactamases.