دراسة القدرة المضادة للأكسدة وللبكتيريا وللتآكل للمستخلصات Limoniastrum Guyonianum )dur.( الفينولية لنبات

Résumé: The present study aims to evaluate the antioxidant, antibacterial and anticorrosion activities for phenolic extracts of the Limoniastrum guyonianum (Dur.) plant of the family Plumbaginaceae in two zones in the South-East of Algeria namely: Ouargla and Oued Souf, in which the phenolic compounds are extracted by four organic systems MeOH/H2O, EtOH/H2O, At/H2O and A.Ac /H2O. At the time of liquid-liquid extraction we have used for each system ethyl acetate and butanol solvents. The chemical detection of the most effective compounds has revealed the existence of phenols, flavonoids, coumarins and tannins, while the absence of alkaloid, glycosides, steroids, terpenes and proteins is recorded. The results of the quantitative evaluation of the phenolic and flavonoid compounds revealed that all the extracts contain a considerable quantity of these compounds whose highest level in the extraction system A.Ac/H2O reached respectively 14235.389mgGAE/100gDWE and 1595.145mgQE/100gDWE in the butanol phase and ethyl acetate for Ouargla plants. In addition, the activity of antioxidants was evaluated by three methods, using the DPPH radical, ferric reducing power (RF) phosphate molybdate (PM) tests, all are chemical methods All phenolic extracts showed considerable antioxidant activity compared to industrial antioxidants. The greatest capacity for inhibition of the DPPH radical in the system A.Ac/H2O in ethyl acetate at a rate of IC50 is 0.0096g/l of the plants, In addition, the At /H2O system in the butanol phase of Ouargla plants has a high AEAC value of 4239μg /ml for the reduction test of Fe+3 to Fe+ 2. This antioxidant activity has also been proved by the TAC value at 6385 mg/g of the reduction of MO (VI) to MO (V) In the electrochemical method, we used Cyclic voltammetry to determine the antioxidant capacity of the extracts by inhibiting the superoxide anion radical 〖 O〗_2^(.-),Butanol extract has shown efficacy in the system A.Ac/H2O to curb the free radical 〖 O〗_2^(.-)in IC50 value 0.009g/l plants Ouargla. The results of antibacterial activity have shown that all the extracts presented an inhibition toward three bacterial strains Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli by using disc agar diffusion method, the ethyl acetate extract in the MeOH/H2O system of the Ouargla plant showed a good activity where the diameter is 46.333 mm against S.aureus and 43mm against E.coli, whereas for the Ethyl acetate extract in the EtOH/H2O system of the Ouargla plant showed good activity where the diameter is 29.666mm against P. aeruginosa. The inhibitory effect of Phenolic components A.Ac/H2O has been estimated from the corrosion of XC52 Carbon Steel in an acid medium by various conventional methods; weight loss; the estimated efficacy was 64.106% at the 20ppm concentration in the butanol of Ouargla plants, but for the Tafal method the inhibitory yield was 93.433% at the 15ppm concentration on the same extract; but for the polarization curve method, the inhibitory yield is 61.464% in the Acetate ethyl extract of the Ouargla plants.

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