Antioxidant and antimicrobial activity of extracts obtained from rosemary (Rosmarinus officinalis) and vine (Vitis vinifera) leaves

The antioxidant properties and antimicrobial activity of rosemary extracts were compared to those of vine leaf extracts. The phenolics were quantified by HPLC. Rosemary extracts were stronger in reducing power than vine leaf extracts but possessed weaker superoxide anion radical (O2 ) scavenging capability. The antimicrobial activity was confirmed by the broth microdilution test using minimal inhibitory (MIC) concentrations against gram-positive (Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes) and gram-negative bacteria (Campylobacter jejuni, Salmonella Infantis, Escherichia coli O157:H7). The kinetics of survival was assessed using the broth macrodilution method. The study confirmed the stronger antibacterial activity of rosemary extracts, especially against gram-positive bacteria and C. jejuni. The antioxidant and antimicrobial activity of vine leaf extracts did not correlate with their contents of flavan-3-ols and flavonols. For rosemary extracts the absence of a correlation between their activities and the content of carnosic acid suggests that protective efficiency is achieved through interactions among phenolic constituents.