Abstract

In addition to their nutritive value, foods provide health benefits or have a role in disease prevention since they contain a wide range of phytochemicals which represent functional or bioactive components. These bioactive molecules present in foods are based on a variety of chemical structures, from carotenoids, through sterols and fatty acids, to different types of polyphenols. In this review, the polyphenols which are common constituents of vascular plants are explored. They are also common constituents of fruits and vegetables, teas and cocoas. The extractable polyphenols, obtainable by solvent extraction of the forest biomass, are of special interest as they are readily available form different types of forest and wood transformation residues. Flavonoids, cinnamic acid derivatives and proanthocyanidins, which share a part of their biosynthetic pathway with lignins, and therefore are associated with “woody” character of the plants, are reviewed along with some non-flavonoids important as food constituents such as stilbenes and hydrolysable tannins. The foods rich in these polyphenols are reviewed along with the forest sources of the same classes of molecules. The emphasis is put on residues of wood transformation such as bark and knotwood as these materials represent particularly rich resources for bioactive polyphenol classes. One of the most notorious bioactive properties of polyphenols is their antioxidant activity. The most important results on antioxidant capacity of forest trees extracts are presented and compared to those obtained for the extracts from healthy foods rich in polyphenols. These results are discussed also in relation to total phenol content of the studied extracts. Finally, the results on the application of selected types of polyphenols or extracts from forest biomass in prevention and/or treatment of diseases which are related to oxidative stress, cardiovascular disease, Alzheimer and cancer, are presented. It is clear from all discussed results, that the forest biomass in general and the residues of wood transformation in particular, represent the important natural resources of bioactive polyphenols. These residues have a real potential to be used as raw materials for the development of food supplements and/or functional foods which can enhance the animal and human health by disease prevention. They are also applicable for cosmetics and pharmaceutical products development, but their application in disease prevention remains more straightforward.

Keywords: Polyphenols, phenylpropanoid pathway, food polyphenols, forest trees polyphenols, cinnamic acids, flavonoids, proanthocyanidins, stilbenes, hydrolysable tannins, antioxidants, oxidative stress, disease prevention, cardiovascular, Alzheimer