Isolation, identification and activity of natural antioxidants from horehound (Marrubium vulgare L.) cultivated in Lithuania

► Two extracts and 8 fractions were prepared from Marrubium vulgare (horehound). ► Fractions were screened for antioxidant activity in four different assays. ► The butanol fraction of the aqueous methanolic extract showed strongest activity. ► On-line HPLC radical scavenging detection was used to pinpoint 5 antioxidants. ► Forsythoside B and verbascoside were not previously reported in M. vulgare.