Cold alkali can extract phenolic acids that are ether linked to cell wall components in dicotyledonous plants (buckwheat, soybean and flax)

Experiments were carried out to estimate the amounts and nature of bonding of ferulic acid to cell walls of various dicotyledonous plant materials inc luding soybean heterotrophic and mixotrophic cell suspension cultures, soyb ean leaves, buckwheat callus, flax phloem and xylem. Isolated cell walls we re oxidized, with CuSO4-NaOH, with phenol aldehyde products and ferulic aci d produced estimated by GC. Ferulic acid content was also analyzed in the c ell wall fraction extracted by 1 M alkali at room temperature, which cleave s ester linkages, and in the fraction extracted by hot concentrated alkali, which cleaves ether linkages. Overall, the bulk of the cell wall ferulic a cid (60-80%) was found to be ether linked to cell-wall components. Room tem perature alkali treatment may release from the cell wall a portion of the f erulic acid that is esterified to cell wall components via saponification. This treatment, however, also extracts a portion of the etherified ferulic acid that is bound to some cell wall components like proteins or glycoprote ins that are acid precipitable. Our results demonstrate that hydroxycinnami c acids can form a significant part (0.01-0.19% of cell wall dry weight) of primary cell wall phenolics of dicots and the nature of linkages between f erulic acid and polymers of the primary cell wall varies in different plant materials. (C) 1998 Elsevier Science Ltd. All rights reserved.