Antioxidant and antimicrobial activities of the edible medicinal halophyte Tamarix gallica L. and related polyphenolic constituents

Tamarix gallica is a halophytic species having hepatotonic and stimulant properties, as it was traditionally used in the treatment of various liver disorders. Leaf and flower infusion have anti-inflammatory and anti-diarrheic proprieties. In this work, we have investigated antioxidant and antimicrobial activities of leaf and flower extracts and their phenolic composition. Results showed that flowers exhibit a higher antioxidant activity as compared to the leaves, IC₅₀ values of the flower extracts are being 1.3 (β-carotene bleaching) to 19 times (lipid peroxidation inhibition) lower than those for leaves. Accordingly, flower extracts exhibited the highest total phenolic content (135.35 mg GAE/g DW) and RP-HPLC analysis showed that syringic acid, isoquercitin as well as catechin were the major phenolics. Furthermore, Tamarix extracts showed appreciable antibacterial properties against human pathogen strains. The mean inhibition zone was from 0 to 6.5 mm when the concentration increased from 2 to 100 mg/l. The strongest activity was recorded against Micrococcus luteus and the lowest activity was observed against Escherichia coli. Moreover, organ extracts show a weakly to moderate activity against the tested Candida. These findings suggest that Tamarix may be considered as an interesting source of antioxidants for therapeutic or nutraceutical industries and for food manufactures.