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Antioxidant and antimicrobial activity of plant phenolics

Introduction: Some researchers suggest that more than two-thirds of the world's plant species have medicinal value. Recent studies have shown that the benefits of plants are usually connected to the presence of phenolics which have an array of biological, pharmacological and health-promoting effects. Antioxidant activity of phenolics is the result of various possible mechanisms such as: radical scavenging activity, reducing ability, metal-chelating activity and/or singlet oxygen-quenching capacity. On the other hand, the mechanism of their antibacterial activity has not yet been elucidated, but it is well known that their activity depend on their chemical structure and concentration. Materials and Methods: In this regard we investigated the phenolics of selected Mediterranean herbs with the aim of finding the connection between their chemical composition and activity. Antioxidant properties were tested by multiple method approach (FRAP, DPPH, ABTS, superoxide anion, Briggs-Rauscher reaction, β-caroten, chelating activity) while antibacterial activity was tested against major food born pathogens (Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Campylobacter coli, Escherichia coli, Salmonella Infantis). Results: The best antioxidant activity was obtained for Lamiaceae plants with high content of rosmarinic acid. Regarding their antimicrobial activity, Gram-negative bacteria were more resistant probably due to presence of the outer membrane surrounding the cell wall which restricts diffusion of compounds through its lipopolysaccharide covering. Conclusion: The research on antioxidant/antimicrobial activity of plant phenolics is important topic to the scientists oriented toward pharmacology and medicinal chemistry. The obtained results point out the differences in phenolic profile of investigated plant extracts, as well as in their antioxidant and antimicrobial properties.

phenolics; SAR; antioxidants; antimicrobials

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