Phenolic profile, antioxidant capacity and antimicrobial activity of Calligonum arich L., desert endemic plant in Tunisia

Abstract

Calligonum arich L. is an endemic plant belonging to the Polygonaceae family and growing in North Africa, particularly in Tunisia. This study aims to determine the phenolic profile and to evaluate the antioxidant and antibacterial activities of C. arich grown in Southern Tunisia environmental conditions. The samples were extracted using methanol solvent. Spectrophotometric methods were used to assess the total polyphenol content (TPC) and total flavonoid content (TFC) using respective standards (gallic acid and quercetin). Individual phenolic compounds were identified using high performance liquid chromatography (HPLC). The in vitro antioxidant capacity was studied adopting three different tests including total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-Azino-bis(3-ethylbenothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities. Results showed that total polyphenol content ranged from 32.02 mg GAE/g DW in roots to 34.27 mg GAE/g DW in leaves. Total flavonoid content ranged from 22.79 to 26.41 mg QE/g DW, respectively in stem and leaves. Qualitative and quantitative HPLC analysis revealed the presence of 14 phenolic compounds that varied significantly with plant parts. Interestingly, the antimicrobial test showed that C. arich leaves extract exhibited the highest antibacterial activity against five microorganisms (two Gram-positive and three Gram-negative bacteria). Moreover, both leaves and roots present a valuable source of phenolic compounds providing to C. arich a high antioxidant capacity with significant variability. This plant could be exploited as a potential source of natural bioactive molecules which confers on this species a greater nutritional value replacing synthetic antioxidants.