Total phenolic, flavonoid and tannin contents and antioxidant and antimicrobial activities of organic extracts of shoots of the plant Limonium delicatulum

Abstract The aim of this study was to assess the antioxidant and antimicrobial activities in vitro of 10 extracts of the halophyte Limonium delicatulum harvested in two physiological stages, flowering and vegetative, and to determine their phenolic compounds by reverse-phase high-performance liquid chromatography. The solvent and the physiological development stage significantly affected the quantity of phenols and the biological activity; the best antioxidant and antimicrobial activities and the most phenolic compounds were found at the flowering stage. Ethanol extracts had the most total antioxidant activity, while the acetone extracts had the greatest radical scavenging capacity (IC50 = 2 μg/mL) and the methanol extract the best inhibition of β-carotene bleaching. The ethanol extract showed the highest total antioxidant activity (177 mg gallic acid equivalents/g dry weight) and antibacterial activity, mainly against Salmonella (16 mm inhibition diameter). The main phenolic compounds were p-coumaric acid and chlorogenic acid.