In vitro Evaluation of Antioxidant Activity of the Methanol and Ethanol Extracts of Pistacia atlantica Desf from Morocco

Abstract

The aim of this work is to evaluate the antioxidant effects of the extracts of Pistacia atlantica collected in the Khenifra region (Morocco) in 2016. Different methods were used to study these extract: 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, the ferric reducing ability of plasma (FRAP) assay, the phosphomolybdate method for determining the total antioxidant capacity, and the electrochemical method for cyclic voltammetry were employed to evaluate the antioxidant capacity of Pistacia atlantica Desf. Phytochemical screening helped us to highlight the presence of secondary metabolites. The extraction of the phenolic compounds was carried out by the Soxhlet method in the presence of different mixtures solvents (ethanol/water and methanol/water); the fractions of the different extracts were affected using ethyl acetate and n-butanol. The dosage results showed that the ethanolic extract was rich in total phenols (260.4 mg GAE/g of the extract) and in total flavonoids (129.15 mg QE/g of the extract), while the butanolic fraction was rich in condensed tannin (50.96 mg CE/g of the extract). The qualitative analysis was performed by high performance liquid chromatography (HPLC). The main compounds that were identified in the methanolic and ethanolic extracts of Pistacia atlantica Desf were ascorbic acid, gallic acid, tannic acid, rutin, and quercetin. The results of the antioxidant activity revealed that the butanolic and ethyl acetate fractions exhibit a good iron reduction capacity (concentration that gave half maximal response, EC50 = 0.02 mg/ml and 0.03 mg/ml, respectively) and a very interesting antiradical activity with an IC50 (concentration of inhibitor where the response is reduced by half) = 0.08 mg/ml and 0.04 mg/ml, respectively. Cyclic voltammetry presented a single oxidation peak between 400 and 500 mV. The ethanolic and methanolic extracts were recorded from the oxidation currents values of 15.75 and 10.41 i/μA cm.2 respectively at the concentration 0.1 mg/ml. Hence, it is clear that the leaves of Pistacia atlantica Desf, which are currently often considered as potential antioxidants, contain antioxidants that can usefully be extracted and added to foods.