Comparison of Lignin-like Products Found Naturally or Induced in Tissues of Phleum, Elodea, and Coleus, and in a Paper Perioxidase System

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Abstract
Lignins were analyzed by means of a difference spectrum technique, a colorimetric determination of phenolic groups, and chromatographic detection of ether soluble components. After alkaline hydrolysis, the lignin-like products of peroxidation of a variety of phenolic compounds were strikingly similar in the above systems, and showed characteristics typical of the phenolic monomer itself. Before alkaline hydrolysis, lignins induced after incubation with ferulic acid and H2O2 differed from natural lignins in the absence of phloroglucinol reacting groups, and in the greater solubility of the product in NaHCO3. Neither saponification nor enzymatic hydrolysis released significant amounts of the ferulic or phydroxycinnamic acids associated with lignin of Phleum or in the product induced with ferulic acid in the above systems. It is postulated that lignin in grasses is made up of 2 components: one is a polymer of ferulic acid and its oxidation products, associated with varying amounts of a comparable phydroxycinnamic acid lignin; the other is a polymer of coniferyl aldehyde or its alcohol and their oxidation products, associated with varying amounts of syringyl units.