Phytochemical Analysis, Acetylcholinesterase Inhibition, Antidiabetic and Antioxidant Activities of Atriplex halimus L. (Amaranthaceae Juss.)

Abstract

Mediterranean saltbush Atriplex halimus L. (Amaranthaceae) from different bioclimatic arid zones (ten wild populations) were studied. Phenols contents, flavonoids, flavonols, tannins and anthocyanins were determined and then tested for their antioxidants, antidiabetic and anti-acetylcholinesterase (AChE) activities. Levels of total polyphenols including flavonoids and flavonols, tannins and anthocyanins were high and varied significantly among analyzed populations. Nine phenolic acids and four flavonoids were identified for the first time in the methanolic fraction and quantified by liquid high-performance chromatography system HPLC (DAD). All extracts showed a substantial antioxidant activity, as assessed by DPPH assay (1,1-diphenyl-2-picrylhydrazyl free radical) (IC_50DPPH=147.3for population of Seliena), Ferric Reducing Antioxidant Power (FRAP; IC_50FRAP=3.2 for populations of Sousse and Kairouan), and Chelation Fer test (IC_50FerCh=1.5 μg/mL for populations of El-hamma and Mednine). Atriplex halimus possessed a high inhibitory effect against α-amylase activity (up to 2.6 mg ACE/gE), a moderate activity for α-glucosidase (up to 91.0 mg ACE/gE) and AChE (up to 147.2 μg/mL) compared to standard. The analyzed populations were isolated and subdivided into three distinct groups, without any bioclimatic structuration. Enzymatic activities seem to be associated with the presence, in plant extracts, of other classes of compounds then phenols such as terpenes, sterols, saponins, coumarins and carotenoids.

Keywords: Antioxidants activities; Atriplex halimus; phenolic compounds; α-amylase inhibition effect; α-glucosidase inhibition effect.