Determination of Sage Tea Polyphenols and Their Antioxidant Effects Using an Electrochemical DNA-Based Biosensor

This study describes two polyphenols, caffeic acid (CA) and (+)-catechin, as well as their antioxidant effects, detected by cyclic voltammetry (CV) using an electrochemical deoxyribonucleic acid (DNA)-based biosensor in sage tea. Square-wave voltammetry (SWV) was applied to investigate CA, as one of the derivatives of phenolic acids, and (+)-catechin, a representative of flavonoids, in sage tea. Square-wave voltammograms (SWVs) of CA showed one peak (0.197 V) and the presence of anodic and cathodic peaks, which suggests an unfolded reversible process on the surface of the glassy carbon electrode (GCE). Furthermore, SWVs of (+)-catechin showed two peaks, which proposes a reversible process at the first peak (0.232 V) and an irreversible process at the second peak (0.6 V) on the surface of the GCE. The determination of the antioxidant effects of sage tea polyphenols was carried out by a DNA-based biosensor. The obtained results indicated that the addition of sage tea to the cleavage solution significantly reduces the degree of DNA degradation. The adopted methods have proved to be simple and applicable tools for the electrochemical characterization of sage tea polyphenols and their antioxidant effects. The study also discusses total phenolic content.