Abstract

Frankenia thymifolia Desf. is an endemic xero-halophyte species common in the salted and arid region of Tunisia. In this study, two kinds of Frankenia shoot fractions were assessed on their polyphenol contents and biological activities. Then, the main phenolic and fatty acid compositions were identified. Results showed that polar fraction contains a highest polyphenol, flavonoïd and tannin contents (14.2 mg GAE g^-1 DW, 4.8 and 4.6 mg CE g^-1 DW, respectively). The higher phenolic content in this fraction reflect the best total antioxidant capacity (8.8 mg GAE g^-1 DW), antiradical activity, β-carotene bleaching and Fe-reducing tests with the lowest IC₅₀ and EC₅₀values as compared to apolar fraction. However, chloroformic fraction was more efficient against pathogen strains. In fact, this fraction was active against all strains. Whereas, polar extract exhibited slight and moderate antibacterial activity (Staphylococcus aureus and Enterococcus faecium, respectively). The high performance liquid chromatography (HPLC) analysis showed that salicylic and transcinnamic acids were the major phenolics. The major fatty acids were palmitic, elaïdic and linoleic acids. Such variability in antioxidant and antimicrobial capacities between the two fractions can be explained by different bioactive compounds contain in each fraction and might be of great importance in terms of valorizing this halophyte as a source of bioactive molecules for cosmetic and pharmaceutical industries.

Key words: Biological activities, fatty acid, Frankenia thymifolia, phenolic, fractionation, high performance liquid chromatography (HPLC).