Structure and Biomedical Properties of Lignins (A Review)

This literature review is in line with current trends in the development of nature-like technologies and is devoted to the analysis of the chemical structure and to the search for new ways to use lignins for biomedical applications. Lignins are unique biopolymers of plant origin, whose structural organization is multivariate and largely depends on the biological species of a plant. Basic structural and chemical studies on various native lignins increasingly refine our knowledge of the macromolecules structure of this key plant biopolymer, and examining lignins of various taxonomic origins shows to what extent evolution and natural variability have resulted in a complication of the chemical structure of the lignin macromolecules, in particular, through the incorporation of “non-traditional” phenolic monomers. This suggests that lignins contain much more structural units than the three traditional monolignol variants described in lignin chemistry textbooks. As a result, the very definition of lignin continues to be expanded and refined. Currently, there is a dramatic increase in interest in lignin-based materials, mainly due to their diverse beneficial properties such as biodegradability, chemical reactivity, biocompatibility, low toxicity, and a wide range of biological activities. One of the main objectives of this review article was to identify and discuss the mechanisms of the biological action of lignins on living organisms with the view to assessing the biomedical potential and substantiating the possibility of use of lignins as innovative drugs with antioxidant, radiation-protective, and geroprotective effects. Finding new ways to use lignins is necessary to meet the challenge of preservation of health, improvement of quality of life, and extension of life expectancy of people.