Abstract
Phenolic contents were determined in S. kali leaves, stems, and roots at the beginning, the mid and the end of the vegetative period, as well as the floral bud and open flower at the reproductive stage. Antioxidant and antimicrobial activities were also assessed. Moreover, the major metabolites were identified by HPLC. Results showed a maximum of total phenol contents in the photosynthetic organs, followed by stems and roots. A similar tendency was found for the flavonoids and condensed tannins. Concerning antioxidant analysis, antiradical and Fe-reduced activities were higher in leaves and stems whereas Fe-chelating activity was higher in leaves and roots. Independently of the plant organ, total phenol and flavonoid contents were maximal at the end of the vegetative period whereas tannin content was maximal at the reproductive one. Phenolic contents were related to the organ, the development stage, and their interaction. Concerning the antimicrobial activity, stem extracts were the most efficient against human pathogen strains (Bacteria: Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus luteus, Escherichia coli and Pseudomonas aeruginosa. Fungi: Candida kefyr, C. holmii, C. albicans, C. sake and C. glabrata). Moreover, nine natural products were identified in leaf and stem extracts of S. kali known for their biological activities. As a whole, biological activities of S. kali seem to be strongly related to organs and to the development stage. The phytochemical tests by HPLC demonstrated the presence of nine compounds among them two alkaloids: salsoline and fraxidin. Some molecules are presented in both organs (salsoline, resorcinol, luteolin 7-o-glucoside; and hyperoside). Therefore, endogenous factors greatly account for the biological potential of this medicinal halophyte.
•Total polyphenols, flavonoid and condensed tannin contents vary by organ and growth•Antioxidant and antimicrobial activities are related to endogenous factors•Nine compounds among them two alkaloids were identified by HPLC