ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF PLANTAGO MAJOR

Objective: The purpose of this research is to evaluate the antioxidant and antibacterial properties of different leaf extracts of Plantago major , using in vitro methods. Methods: The antimicrobial activity of different extracts (petroleum ether, ethyl acetate and aqueous fractions) from Plantago major leaves and their synergistic effect with standard antibiotic (Gentamicin) were evaluated using the disc diffusion method. The total phenolic and total flavonoid content of these extracts was determined according to the Folin-Ciocalteu procedure and Aluminum chloride colorimetric assay respectively. Antioxidant properties were determined via the DPPH free radical scavenging, β-carotene bleaching assay and ferrous ion chelating activity. Results: The total phenols and total flavonoid content of the extracts ranged from 5.79 to 114.45 mg GAE/g dry extract and from 1.24 to 5.48 µg QAE/mg dry extract respectively. The ethyl acetate fraction showed the highest DPPH scavenging capacity (IC 50 = 12.85±0.27 µg/ml) and relative antioxidant activity of 70.48% in the β-carotene bleaching assay. While, aqueous and petroleum ether fractions have the lowest activities. On the other hand, only the aqueous fraction has a capacity of chelating iron (IC 50 = 1.02±0.02 mg/ml). The findings indicated also that an ethyl acetate fraction was the most active in vitro against Gram-negative and Gram-positive bacteria strains. High inhibition zone of 16.7±1 mm and 14.3±0.6 was exhibited on Staphylococcus aureus and Bacillus cereus . Moderate one of 13.3±0.6 and 11.3±0.6 mm was obtained against Pseudomonas aeroginosa and Acinetobacter bowie . However, lowest antibacterial activity was obtained against Klebsiella pneumonia , Proteus mirabilis and Salmonella typhimurium . Furthermore, synergistic antibacterial activity was either obtained by the combination of standard antibiotic (Gentamicin) with the tested extracts. Conclusion: Our results showed a potent antioxidant and antibacterial activities of this species. This plant could be exploited as a potential source of natural antioxidant and antimicrobial agents for dreadful human diseases and oxidation prevention.