Total phenol content, total flavonoid content and, In vitro, antibacterial activity of Polygonum aviculare and Zygophyllum album extracts from algeria against multidrug-resistant gram-negative bacteria (MDR-GNB)

This study aimed to evaluate in-vitro the antibacterial activity of Polygonum aviculare and Zygophyllum album extracts against multidrug-resistant Gram-negative bacteria (MDR-GNB) and to determine their total phenol content (TPC) and total flavonoid content (TFC). The effect of methanol and ethanol plant extracts was investigated against 3 Gram-negative reference strains (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 700603) and four clinical MDR-GNB strains (Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli 1 and Escherichia coli 2) by disc diffusion using 2 concentrations (100 and 200 mg/mL). The results revealed that P. aviculare extracts (methanol or ethanol) exhibited significant activity against different MDR-GNB strains with inhibitory zones ranging from 9 to 19 mm, while Z. album extracts showed antibacterial activity against E. coli 1, P. aeuginosa, E. coli ATCC 25922 and K. pneumoniae ATCC 700603 with inhibitory zones varying between 9 to 10.66 mm. The TFC values of plants extracts showed that the highest phenolic contents were found in methanol and ethanol extracts of P. aviculare (161.99±11.93 and 158.73±8.36μg GAE/mg respectively). Whereas both Z. album methanol and ethanol extracts contained considerably lower content of phenols (19.55±1.79 and 25.40±2.39μg GAE/mg). The TFC values also showed similar trends with that of TPC values. The highest TFC values were obtained for P. aviculare extracts (30.87±3.76μg QE/mg for methanol extract and 46.43±5.82μg QE/mg for ethanol extract), and the lowest were for Z. album extracts (19.14±6.11 for methanol extract and 21.40±0.98 μg QE/mg for ethanol extract).