In vitro Antioxidant and Antibacterial Activity of Lamiaceae Phenolic Extracts: A Correlation Study

Ivana Generalić Mekinić^1*, Danijela Skroza¹, Ivica Ljubenkov², Vida Šimat³, Sonja Smole Možina⁴ and Višnja Katalinić<sup>1

1</sup>University of Split, Faculty of Chemistry and Technology, Teslina 10, HR-21000 Split, Croatia
²University of Split, Faculty of Science, Teslina 12, HR-21000 Split, Croatia
³University of Split, University Department of Marine Studies, Livanjska 5/III, HR-21000 Split, Croatia
⁴University of Ljubljana, Biotechnical Faculty, Jamnikarjeva 101, SI-1111 Ljubljana, Slovenia

Article history:
Received August 29, 2013
Accepted January 14, 2014

Key words:
Lamiaceae, phenolics, rosmarinic acid, antioxidant properties, antimicrobial activity, principal component analysis

Summary:
Total phenols and phenolic subgroups of five Lamiaceae plant extracts (sage, thyme, lemon balm, peppermint and oregano) were determined spectrophotometrically, whereas the individual phenolics were determined by high-performance liquid chromatography. The antioxidant activity of the extracts was evaluated by means of a multiple method approach, while the antibacterial activity was tested against major foodborne pathogens such as Campylobacter coli, Escherichia coli, Salmonella Infantis, Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. The highest content of total phenolics and non-flavonoids was detected in the sage extract, which also showed the best antibacterial activity, especially against Gram-positive bacteria and C. coli. The best reducing power and free radical scavenging activity were obtained in lemon balm extract, with the highest content of rosmarinic acid. Additionally, the effect of the phenolics, especially rosmarinic acid, on biological properties of Lamiaceae plant extracts was investigated using principal component analysis. Rosmarinic acid showed good correlation with all antioxidant parameters, confirming its significant contribution to antioxidant activity of investigated plant extracts.

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