Effects of cinnamic acid on polyphenol production in Plantago lanceolata

Abstract

Ribwort ( Plantago lanceolata) contains two main caffeic acid glycoside esters, plantamoside and verbascoside. These two polyphenols were investigated in the aerial and underground parts of in vitro cultured ribworts. For the first time, it is reported that, whatever the age of this plant, plantamoside and verbascoside are concentrated in the roots with plantamoside levels double those of verbascoside. When P. lanceolata was transferred into a medium containing 10 −3 M ( E)-cinnamic acid, this chemical stress induced a slow degeneration of the initial roots. These were superseded by neoroots whose morphology was atypical during the first eight days following their appearance. In the initial roots, ( E)-cinnamic acid induced a temporary appearance of two cinnamic acid derivatives (NCD), but did not change the plantamoside and verbascoside levels. In the neoroots, high NCD levels were detected for only eight days. After the large decrease of these NCD, plantamoside and verbascoside appeared and increased. These NCDs have been identified as glucoside esters of ferulic and p-coumaric acids. These two compounds, which are absent from the traditional chemical profile of ribwort, probably arose from a ( E)-cinnamic acid detoxification pathway.