Optimization of Antioxidant and Antimicrobial Activities by Fractionation of Artemisia judaica subsp. sahariensis Crude Extract from Ahaggar (Algerian Arid Region): UPLC-ESI-MS/MS Analysis of Fractions

Background: In recent years, medicinal plants have received considerable attention due to the search for novel bioactive compounds. In this optic, we have been interested in Artemisia judaica subsp. sahariensis, a Saharan species widely used in phytotherapy by the Tuaregs of the Ahaggar. Objectives: This study aims to evaluate and optimize the biological activities of this plant in order to valorize its bioactive compounds. Methods: For this purpose, an extraction with methanol (70%) was carried out, then a liquid-liquid fractionation, using solvents with increasing polarity: diethyl ether, ethyl acetate, n-butanol and water. We realized an analysis of phenols, flavonoids and evaluation of antioxidant and antimicrobial activities in addition to the UPLC-ESI-MS/MS analysis of the fractions. Results: The reducing effect was proportional to the solvent polarity. The crude extract gave the best reducing power (17.55 ± 3.06 μg/mL), better phenols and flavonoids contents (20.35 ± 0.5 mgGAE/gTDM), (10.35 ± 0.56 mgGAE/gTDM) respectively compared to its fractions. The DPPH (2,2-Diphenyl-1-Picrylhydrazyl) radical scavenging assay showed that the ethyl acetate fraction was the most active with the lowest IC50 value (inhibitory concentration to 50% of DPPH) (41.43 ± 0.24 μg/ml) followed by n-butanol (58.53 ± 0.20 μg/mL), diethyl ether (135.07 ± 6.18 μg/mL) and aqueous (226.41 ± 1.51 μg/mL) fractions (p <0.0001). Moreover, hydromethanolic extract gave an IC50 value of 114.05 ± 3.37 μg/mL. The antimicrobial effect was observed on all clinical multiresistant bacteria tested except Klebsiella pneumoniae, which was resistant. The most important effect was observed by the ethyl acetate fraction against the fungal strain Candida albicans. Various phenolic acids and flavonoids (flavones, flavonols, flavanones) were detected and could be responsible for these bioactivities. Conclusion: We can conclude that liquid-liquid extraction with solvents of increasing polarity plays a major role in optimizing the biological activity of this plant, which contains polyphenols and can therefore be valued as a source of natural antioxidants and antimicrobials.