Polycommunin A, a dihydrocinnamoyl bibenzyl isolated from the moss Polýtrichum commúne, and its antioxidant activity.

A novel polyphenolic compound named Polycommunin A (1) was discovered in the aerial part of the common haircap moss (Polýtrichum commune) widely spread in boreal and temperate climate zones. Aqueous ethanol and extraction of the plant material with further isolation of polyphenolic fraction and preparative HPLC separation allowed obtaining individual compound and identifying it as dimeric dihydrocinnamoyl bibenzyl by NMR spectroscopy and high-resolution tandem mass spectrometry. Polycommunin A demonstrated high in vitro antioxidant activity determined by FRAP and PCL assays and comparable to that of Trolox and Quercetin.

Analysis of the functional group composition of the spruce and birch phloem lignin.

In this article, the functional group composition of the spruce (Pícea ábies) and birch (Bétula péndula) phloem lignin is described. The features of the chemical structure were studied by analyzing dioxane lignin using the elemental analysis, UV-Vis, FT-IR, and 1D NMR spectroscopy. For comparison, samples of xylem dioxane lignin isolated from the corresponding wood species were also analyzed. FT-IR spectroscopy data suggest that the lignins of birch phloem and xylem are similar in chemical structure. However, there are differences in absorption bands in the spectra of spruce dioxane lignin, which indicate the opposite. Quantitative analysis of the functional group composition was performed using 13C and 31P NMR data. It was found that free phenolic hydroxyl groups of catechol and p-hydroxyphenyl types are dominated in the composition of spruce phloem lignin. Birch phloem lignin has a qualitative and quantitative composition of functional groups characteristic of hardwood lignins. However, the content of G-units is greater than S-units, in contrast to the birch xylem lignin, where S-units predominate. The revealed differences are relevant from the point of view of plant physiology. The practical significance of the study is connected with understanding the reactivity of lignins when considering the chemical processing of tree bark.

Structural characterization of the lignin from Saxifraga (Saxifraga oppositifolia L.) stems.

As a renewable source of unique aromatic compounds, lignin attracts the attention of many researchers. However, for its successful application, it is necessary to have a clear and accurate idea of its chemical structure. Therefore, it is necessary to expand knowledge about the structure of lignins of various nature using the informative analytical methods. The aim of this study was to characterize the dioxane lignin of the Saxifraga oppositifolia L. - the northernmost angiosperm. The lignin of plants growing in the Arctic zone may differ significantly from other plants, both due to species differences and peculiarities of growing conditions. Studies were conducted on an isolated lignin preparation obtained by the Pepper's method. Analysis of Py-GC/MS data and NMR spectroscopy showed that saxifrage lignin belongs to GH-type. This is evidenced by a significant proportion of p-hydroxyphenyl units (40%), while the content of syringyl units is about 14%. The major substructures of the studied lignin were ß-aryl ether, phenylcoumaran, and resinol. It was found that the γ­carbon of the lignin side chains are partly acetylated, and forms ester bonds with the p-hydroxybenzoate structure. In addition, the NMR spectrum showed a signal of the phenylglycoside evidenced the presence of the lignin-carbohydrate complex.