Identification by NMR and accumulation of a neolignan, the dehydrodiconiferyl alcohol-4-β-D-gluco side, in Linum usitatissimum cell cultures

Phenylpropanoids represent a broad range of secondary metabolites in plants, in which they are involved in defense mechanisms. This study deals with the NMR identification of a phenylpropanoid, which belongs to the class of neolignans, dehydrodiconiferyl alcohol-4-beta-d-glucoside (DCG), in in vitro cultures of Linum usitatissimum. The combination of 1- and 2-D NMR experiments such as COSY, HMBC and HMQC allowed the identification of this compound's structure unambiguously. In order to evaluate its implication in defense mechanism, the L. usitatissimum suspension cells were placed together with fungal extracts. Consequently, the DCG concentration decreased dramatically after 96 h of treatment. In correlation, the phenylcoumaran benzylic ether reductase (PCBER) expression increased rapidly and constantly immediately after elicitation until 96 h post elicitation, as shown by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). These two results are in agreement, since the aglycone form of DCG is one of the two substrates of PCBER, thus suggesting PCBER activation in plant defense mechanisms.