HPLC/UV Analysis and In Vitro, Promising Antioxidant, Antidiabetic, Anti-Alzheimer, and Anti-Tyrosinase Potentials of the Algerian Pistacia atlantica Desf. Methanolic Extract

Abstract

The main objective of this work is to evaluate the species Pistacia atlantica by analyzing the chemical composition of the methanolic extract of the plant leaves; then by determining its content on phenolic compounds, flavonoids and condensed tannins; and finally by testing its antioxidant and inhibitory activities against some enzymes involved in several diseases. To identify phenolic compounds, a high-performance liquid chromatography analysis with ultraviolet detector was used; Folin–Ciocalteu trichloroaluminum and vanillin methods were carried out for phenolic compounds, flavonoids, and condensed tannins quantification, respectively. The antioxidant effect was tested by five different methods. Acetylcholinesterase, butyrylcholinesterase, α-glucosidase, and tyrosinase were used to evaluate the inhibitory power of the plant against those enzymes. The results indicated the presence of phenolic compounds in the extract, including phenolic acids and flavonoids. The total phenolic compounds, flavonoids, and condensed tannins contents obtained, respectively, were equal to 36.089 ± 0.047 mg equivalent of galic acid per gram, 0.775 ± 0.01 mg equivalent of quercetin per gram, and 5.44 ± 0.5 mg of equivalent catechin per gram of dry plant. High antioxidant activity was observed and it was expressed by IC50 ranging from 3.50 ± 0.05 to 11.11 ± 4.03 μg/ml and concentrations at absorbance 0.5 from 0.84 ± 0.08 to 54.57 ± 0.24 μg/ml values. Strong antidiabetic effect was recorded which far exceeds the effect of acarbose, and interesting anti-Alzheimer and anti-tyrosinase effects were noted.