Quantification of total phenols, flavonoides and tannins from Ziziphus jujuba (mill.) and Ziziphus lotus (l.) (Desf). Leaf extracts and their effects on antioxidant and antibacterial activities

This work was performed to determine the biochemical composition, antioxidant and antimicrobial activities of leaf extracts collected from four different provenances: Mahdia and Mahres (Ziziphus jujuba); Kairouan and Rouhia (Ziziphus lotus). Total phenols, flavonoids, tannins contents and antioxidant activity were evaluated using the Folin ciocalteux, Aluminum trichloride, vanillin and scavenging activity on 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals methods, respectively. The antimicrobial activity was evaluated against three bacterial strains (Escherichia coli, Staphylococcus aureus and klebsiella pneumoniea) and three fungal strains (Fusarium culmorum, Fusarium solani and Botrytis cinerea), according to well Agar diffusion method. Total phenols and flavonoids were present at levels of 21.98 mg GAE /g DW and 7.80 mg ER/g DW; respectively in Ziziphus lotus. These levels did not exceeded 13.70 mg GAE /g DW and 6.73 mg ER/g DW for Ziziphus jujuba. The tannin contents were present in equal levels (7.9 mg EC/g DW) in two species. The high antioxidant activity (0.01 µg/ml) was noted in Rouhia provenance. The Ziziphus lotus leaf extracts showed promising efficiency against all tested microorganisms with a zone of inhibition ranging between 22 and 23.5 mm. This study could validate the medicinal potential of Ziziphus specie and explain why tunisian people traditionally use it in medicine to treat several pathologies. Ziziphus leaf extracts may be suggested in foods and pharmaceutical industries. Leaf extracts proved also to be effective against tested microorganisms. So, an adequate toxicological study must be carried out to verify the possibility of using these plants for fighting microorganisms