Chemical composition, mineral content and antioxidant activity of Verbena officinalis L.

Abstract

Aqueous and hydroalcoholic extracts from Verbena officinalis L. were obtained and characterised. The analysis by HPLC-DAD and LC–MS allowed the detection and identification of three iridoids, fifteen flavonoids and four phenolic acid derivatives. Four flavonoids, scutellarein 7-diglucuronide ( 9), scutellarein 7-glucuronide ( 13), pedalitin 6-galactoside ( 15) and scutellarein 7-glucoside ( 19) are reported for the first time from this plant. In addition, three new flavonoids have been isolated: scutellarein 7- O-(2- O-feruloyl)-diglucuronide ( 5), pedalitin 6- O-diglucuronide ( 6) and pedalitin 6- O-(2- O-feruloyl)-diglucuronide ( 13). To our knowledge, these flavonoids have not been reported as natural products. Both extracts showed significant antioxidant activity using three in vitro model systems and the results have been correlated with total phenolic and total flavonoid contents. The results have allowed establishing an important relation structure–activity and significant correlations have also been found between the mineral content and the flavonoids present in both extracts.