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Antioxidant/pro-oxidant activity of Teucrium arduini L.: phytochemical, molecular and cell- based approaches

Oxidative stress has been recognized as the main cause of many types of chronic diseases. Therefore antioxidants, which may directly react with the reactive radicals and inhibit their prooxidative nature, attract much attention in the prevention of chronic diseases development. Synthetic antioxidants are not preferred for pharmacologic use due to toxicological concerns, thus more interest has been focused on identifying plant extracts to use as dietary antioxidant supplements. One of the most thoroughly studied groups of plant secondary metabolites with antioxidant properties are polyphenolic compounds. In research presented here, we investigated antioxidant/pro-oxidant capacity of endemic Teucrium arduini L. extracts using biochemical and biological approaches. In details, phytochemicals were investigated with respect to influence of growing location, antioxidant activity was determined using three in vitro antioxidant activity assays (DPPH, ABTS, FRAP), and antioxidant/prooxidant effect of plant extract was evaluated on macromolecule (DNA, protein, lipids) and cell (human laryngeal carcinoma -HEp2) levels. Extract with the highest polyphenolic content, free radical scavenging activity and ferric reducing-antioxidant power showed also DNA protective effect, inhibition of lipid peroxidation and cytotoxic activity. However, the same extract showed pro-oxidant effect in the protein oxidation assay, and such action was confirmed in HEp2 cells in which treatment with T. arduini extract at higher concentration induced the ROS formation. Thus, the paradox situation could be caused by the chemistry of phenolic compounds. It is known that polyphenols have the capacity to participate in redox reactions, and may act as reducers and oxidizers i.e. antioxidants and pro-oxidants. Causally, T. arduini extracts with antioxidant/pro-oxidant activities could be interesting as source of phytochemicals useful in treatment of disease in which cell death through apoptosis or necrosis, induced via oxidative stress-related mechanisms, is a desired outcome.

phytochemical; plant extract

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