Phenolic Profiling, Antioxidant, and Antibacterial Activities of Selected Medicinal Plants from Tunisia.

Phytochemical screening of aqueous extract from six medicinal wild plants grown in South-eastern of Tunisia: Atriplex halimus, Teucrium polium, Moricandia arvensis, Deverra tortuoa, Haplophyllum tuberculatum and Polygonum equisetiforme were evaluated. Both decoction and ultrasound assisted extraction were used. Antioxidant, antibacterial proprieties, and phenolic profiling, using LC-ESI-MS method, were assessed. Total polyphenols, flavonoids, and condensed tannins contents ranged from 7.47±0.19 to 22.25±0.49 mg GAE/g Dw, 5.47±0.06 to 7.55±0.07 mg RE/g Dw, and 0.33±0.02 to 19.43±0.64 mg TAE/g Dw, respectively. Moreover, the reducing power and DPPH tests showed that P. equisetiforme (EC50 : 12.50±0.50 µg/ml; DPPH⋅+ : 213.49±4.24 mg TEAC/g DW), T. polium (EC50 : 25.00±1.00 µg/ml; DPPH⋅+ : 181.39±9.47 mg TEAC/g DW) as well as H. tuberculatum (EC50 : 56.25±0.25 µg/ml; DPPH⋅+ : 177.83±5.85 mg TEAC/g DW) extracts were the most effective natural antioxidants. For anti-bacterial activity, the ultrasonic extract of H. tuberculatum showed the highest activity against both P. aeruginosa (13.50±0.71 mm) and S. aureus (13.00±0.00 mm) at 10 mg/ml. Furthermore 24 phenolic compounds were identified, with predominance of quinic acid, gallic acid, protocatechuic acid, syringic acid, p-coumaric acid, trans-ferulic acid, catechin (+), trans-cinnamic and silymarin. These results were further consolidated by to heatmap clustering with P. equisetiforme, H. tuberculatum, T. polium as the main antioxidant and antibacterial sources which supports their domestication and industrial use.

Influence of Extraction Techniques and Solvents on the Antioxidant and Biological Potential of Different Parts of Scorzonera undulata.

The genus Scorzonera has various medicinal values. Species belonging to this genus were traditionally used as drugs or in food. The current study aimed to determine the phytochemical composition, antioxidant activity, and biological properties of the tuber, leaf, and flower of Scorzonera undulata extracts, collected from the southwest of Tunisia. Phenolic compounds from the three parts were extracted using two solvents (water and ethanol) and two extraction techniques (maceration and ultrasound). The total phenolic content was measured by the Folin-Ciocalteu assay. Furthermore, the chemical composition of Scorzonera undulata extract was also investigated by the LC-ESI-MS method using phenolic acid and flavonoid standards. The variation of the extraction methods induced a variation in the real potentialities of the three parts in terms of bioactive molecules. However, the aerial part of S. undulata (leaves and flowers) showed, in general, the highest phenolic contents. Twenty-five volatile compounds have been detected by GC-MS in S. undulata extracts; among them, fourteen were identified before derivatization. The DPPH test showed that the aerial part of the plant has a higher antioxidant activity compared to the tuber (25.06% at 50 µg/mL for the leaf ethanolic extract obtained by ultrasound extraction). For most biological activities (anti-Xanthine, anti-inflammatory, and antidiabetic (alpha-amylase and alpha-glucosidase)), the aerial parts (flowers and leaves) of the plant showed the highest inhibition than tubers.