Gentiana asclepiadea exerts antioxidant activity and enhances DNA repair of hydrogen peroxide- and silver nanoparticles-induced DNA damage

► We performed a quantitative analysis of Gentiana asclepiadea aqueous and methanolic extracts. ► Mangiferin and an unidentified polar compound are the most pronounced antioxidants. ► Extract from haulm exhibited stronger antioxidant properties compared with flower extracts. ► Flower and haulm extracts enhanced repair of H2O2-induced DNA damage in human lymphocytes. ► Repair of DNA damage induced by nanosilver was stimulated by plant extracts in HEK 293 cells.