Phytochemical Screening and Assessment of Antioxidant, Antibacterial and Cytotoxicity Activities of Five Tunisian Medicinal Plants

The present study was carried out to investigate the phytochemical compositions, antioxidant and antibacterial activities, and the cytotoxicity of aqueous and methanolic crude extracts of five wild medicinal plants from the south of Tunisia. The phytochemical screening was quantified by calorimetric techniques in terms of the total contents of phenolic compounds and total condensed tannin content. The results showed that the methanolic extracts of Thymelaea hirsuta L (44. 23 ± 1.96 mg GAE/g DW) possessed the highest total phenolic content and the total condensed tannins. The antioxidant activity was assessed in vitro by using both the scavenging activity of DPPH radical and phosphomolybdenum total antioxidant assay. The findings showed that the methanolic extract of Thymelaea hirsuta L, and the aqueous extract of Artemesia campestris L showed the strongest radical scavenging activity by the DPPH assay (IC50 values = 1.74 ± 0.12 μg/mL and 0.77 ± 0.18 μg/mL, respectively) compared to the standard, ascorbic acid and BHT. The height antioxidant capacity by the formation of phosphomolybdenum complex was obtained for the methanolic extracts of T. hirsute and A. campestris (57.54± 0.46 mg AAE /g and 55.75± 3.76 mg AAE /g). Furthermore, the extracts were evaluated for its antibacterial activity using the disc agar diffusion. The results have demonstrated that the methanolic extracts of Thymelaea hirsuta L and Artemesia campestris L were most effective against the selected bacteria. The cytotoxicity was analyzed by examining haemolytic activity against chicken erythrocytes, the results clarified that only the methanolic extract of Cleome arabica L was able to generate haemolytic activity with 30.45 ± 0.63 %.