EFFECTS OF CINNAMIC ACID ON POLYPHENOL PRODUCTION IN PLANTAGO-LANCEOLATA

Ribwort (Plantago lanceolata) contains two main caffeic acid glycoside esters, plantamoside and verbascoside. These two polyphenols were inv estigated in the aerial and underground parts of in vitro cultured rib worts. For the first time, it is reported that, whatever the age of th is plant, plantamoside and verbascoside are concentrated in the roots with plantamoside levels double those of verbascoside. When P. lanceol ata was transferred into a medium containing 10(-3)M (E)-cinnamic acid , this chemical stress induced a slow degeneration of the initial root s. These were superseded by neoroots whose morphology was atypical dur ing the first eight days following their appearance. In the initial ro ots, (E)-cinnamic acid induced a temporary appearance of two cinnamic acid derivatives (NCD), but did not change the plantamoside and verbas coside levels. In the neoroots, high NCD levels were detected for only eight days. After the large decrease of these NCD, plantamoside and v erbascoside 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, p robably arose from a (E)-cinnamic acid detoxification pathway. (C) 199 8 Elsevier Science Ltd. All rights reserved.