Characterisation of phenolic antioxidants in aqueous extract of Orthosiphon grandiflorus tea by LC-ESI-MS/MS coupled to DPPH assay

► Orthosiphon grandiflorus tea was investigated for its antioxidant components. ► An LC-MS/MS coupled with DPPH assay was used in the study. ► Rosmarinic acid was found as a major antioxidant of this plant. ► The rest were danshensu, caftaric acid, sagerinic acid and salvianolic acid B.