Antiradical and antibacterial activity of Echium altissimum extracts on human infective bacteria and chemical composition analysis

The evolution of bacterial strains with greater resistance to conventional antibiotics has led to the use of new generations of antibiotics. This research aimed to investigate the antiradical and antibacterial properties of a methanol extract from the aerial and underground parts and seeds of Echium altissimum (Syn. Echium italicum) on pathogenic bacteria. The samples (i.e., aerial and underground parts and seeds) of E. altissimum were collected from Urmia, Iran. The antibacterial properties were analyzed by agar well diffusion assay. In addition, the minimum inhibitory and bactericidal concentrations were measured by the serial dilution method. However, the phenolic and flavonoid contents were obtained by the Folin-Ciocalteu and Aluminum chloride methods, respectively. Furthermore, free radical scavenging activity was measured by 2, 2-diphenyl-1-picrylhydrazyl. The most susceptible was obtained for Micrococcus luteus on the seed methanol extract of E. altissimum. Next, the IC50 of the aerial and underground parts and seeds were determined as 0.1054, 0.1278, and 0.1508 mg mL^-1, respectively. The methanol extract of seed exhibited a MIC of 0.75 mg mL^-1 against M. luteus. Lastly, the highest phenol and flavonoid contents were determined as 246.12 (mgGA/g) and 6.29 (mgQ/g) from the seed methanol extract. The major compounds were determined to be rosmarinic acid (28.36%) and myricitrin (12.38%). In general, E. altissimum exhibited antibacterial and antioxidant activity and is therefore suggested for producing natural antibiotics and rare drugs, especially anti-infective drugs for the pharmaceutical science.