ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF SIX ALGERIAN MEDICINAL PLANTS

Objective: This work had two objectives: the first, to evaluate the total phenolic or flavonoid contents of six Algerian medicinal plants and second, to determine whether these compounds have antioxidant properties and antimicrobial potential.Methods: The polyphenolic extractions of the dried powdered samples have been performed using 80 % methanol. Total phenols and flavonoids concentrations were analyzed using Folin-Ciocalteu's and aluminum chloride methods. The antioxidant activity was investigated with three different methods: the β-carotene bleaching (BCB) test, the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH)free radical scavenging method and the ferric reducing activity power (FRAP) assay. Polyphenols from the medicinal plants were screened for their antibacterial activities against pathogenic microorganisms (Staphylococcus aureus, Pseudomonas aeruginosa and Esherichia coli) using agar disc diffusion method and minimum inhibitory concentration.Results: The total phenolic and flavonoids contents of the samples varied from (30.34±0.52) mg GAE/g extract to (602.71±2.01) mg GAE/g extract and from (16.61±0.04) mg QE/g extract to (21.91±0.31) mg QE/g extract, respectively. The antioxidant activity measurement, expressed as percentage inhibition of DPPH free radical, ranged from (44.00±0.06) % to (95.70±0.49) %. With further data analysis, it was found that there was a positive correlation between the total phenolic content of a given sample and its antioxidant activity (R2= 0.8064). The results showed that a remarkable inhibition of the bacterial growth was shown against the tested microorganisms. The phytochemicals analyses of the plants were carried out. The microbial activity of the plants extracts was due to the presence of various active compounds.Conclusion: These results suggest that phenolic compounds in these plants provide substantial antioxidant and antibacterial activities which vary to a great extent. Hence, these plants can be used to discover bioactive natural products that may serve as leads for the development of new pharmaceuticals research activities.Â