Antibacterial and antioxidant activities of various extracts and essential oil from dried leaves of Artemisia herba-alba Asso of Tamanrasset (South Algeria)

The objective of this study was to evaluate the antibacterial and antioxidant activities of two extracts (aqueous and ethanolic) and essential oil from dried sheets of Artemisia herba alba collected in southern Algeria. The extracts were prepared separately with different polarity solvents (water and ethanol). Total phenolics, flavonoids and tanins contents were evaluated. The essential oil was isolated using hydrodistillation. Two tests were established to assess the antioxidant activity (DPPH and FRAP), agar-well diffusion method was used to evaluate the antibacterial effect: Escherichia coli, Enterococcus faecalis, Staphylococcus aureus and Bacillus cereus. The yield of the aqueous extract is higher than that of the ethanolic extract. The phytochemical study revealed the presence of phenolic compounds, flavonoids and tannins. The aqueous extract contains higher amounts of total phenolics (97.17 ± 1.06 mg/g DM), flavonoids (35.61 ± 0.39 mg/g DM) and tannins (46.58 ± 0.91 mg/g DM) compared to the ethanolic extract, 28.69 ± 0.99, 10.98 ± 0.64 and 15.11 ± 0.49 mg/g DM respectively. Antioxidant activity (IC50) of aqueous, ethanolic extracts and essential oil were 2.02, 0.753 and 1.088 mg/ml, respectively. Analysis of the antibacterial activity showed that aqueous extract exhibited much higher activity that the ethanolic extract and essential oil. RP HPLC analysis of aqueous extract show the presence of certain compounds that belong to flavonoids (cathecine and apigenin) and others to phenolic acids (caffeic acid and ferulic acid). The results of this study demonstrated that the essential oil and extracts can be used as antioxidant and antimicrobial agents.