ABSTRACT
Microbial infections remain public health problems because of the upsurge of bacterial resistance. The presentstudy aimed to evaluate the anti-quorum sensing, antimicrobial activities, and chemical compositions ofAcacia macrostachya. Total phenolic, flavonoid, and condensed tannin content were determined according toFolin–Ciocalteu, aluminum chloride, and Broadhurst methods, respectively. The microdilution method usingp-iodonitrothétrazolium was used to evaluate the antibacterial activity. Inhibition of pyocyanin and violaceinproduction by extract and fraction was used to evaluate anti-quorum sensing activity. The antioxidant activitywas evaluated using 2,2-diphenyl-1-picryl-hydrazyl, Ferric reducing, and hydrogen peroxide scavengingmethods. The minimum inhibitory concentration of the extracts and fractions ranged from 0.312 to 5 mg/ml.At 100 µg/ml, ethyl acetate fraction significantly inhibited the production of violacein (56.45%) and pyocyanin(48.88%). The total phenolic, flavonoids, and condensed tannin contents ranged from 31.85 ± 0.31 to 21.26± 0.67 mg gallic acid equivalent (GAE)/100 mg, 26.35 ± 0.71 to 25.42 ± 0.36 mg quercetin equivalent (QE)/100mg, and 18.24 ± 0.12 to 15.9 ± 0.17 mg Catechin equivalent (CE)/100 mg, respectively. The antioxidantactivity correlates with phenolic, flavonoids, and tannin contents. High Pressure Liquide Chromatography(HPLC) analysis of the ethyl acetate fraction allowed to identify three phenolic acids and five flavonoids. Theresults described here could justify the use of A. macrostachya by traditional healers to treat infections, andparticularly, gastrointestinal disorders.