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.
ABSTRACT
In the Benin pharmacopoeia, the use of Ocimum gratissimum Linn (Lamiaceae) based on the empiricalknowledge is widespread. The objective of this work is the matching of the virtues attributed to this plant in folkmedicine with the biomolecules present through a thorough phytochemical exploration. Standard screeningis based on the differential reactions of precipitation and staining. Phenolic compounds, total flavonoids,and condensed tannins were quantified by colorimetric Folin–Ciocalteu, AlCl3, and acid vanillin methods,respectively. Phenolic acids were investigated by the HPLC Ultimate 3000 chain and the antioxidant capacityevaluated by the ferric reducing antioxidant power method coupled with that of 2,2-diphenyl-1-picrylhydrazyl.Standard screening revealed the presence of flavonoids, alkaloids, tannins, anthracene derivatives, steroids, andterpenoids. The total contents of phenolics, flavonoids, and tannins were 56.59 mg gallic acid equivalent /100mg, 13.71 mgEQ/100 mg, and 8.6 mgEC/100 mg, respectively. For specific assays, three flavonoids (chrysin,isorhamnetin, and quercetin) and six phenolic acids (tannic, ellargic, ferrulic, syringic, chlorogenic, and caffeic)have been identified. The antioxidant activity ranges from 78.92 to 106.25 mmol. Ascorbic acid equivalent /gextract with free radical inhibition ranging from 5.24% to 76.59%. The 50% inhibitory concentration givinga value of 6.175 mg ml−1 is greater than that of the pure molecule. The presence of these phytocompoundsendowed with antiradical power testifies to the medicinal potentialities of O. gratissimum. These resultsconfirm the empirical use of O. gratissimum in this study area