Extracts from pine and oak barks: phenolics, minerals and antioxidant potential.

Residues of wood, such as bark, represent an attractive source for natural antioxidants. The aim of this study was to evaluate the total polyphenols, heavy metals content and antioxidant capacity from oak (Quercus robur L.) and pine (Pinus sylvestris L.) barks grown in the central region of Poland. Identification and quantification of flavonoids and phenolic acids were done by HPLC-MS analysis. The phenolic extraction yields for oak barks were higher than for pine barks, while higher content of total flavonoids was determined in pine bark extracts. Generally, the content of the metals in raw barks and their extracts decreased in the order: Zn > Cu > Cr > Pb > Ni > Cd. The extracts were able to quench DPPH· radicals and to reduce the cupric complex exhibiting good antioxidant properties. They can be utilised as additives in nutraceutical and cosmetic products as well as for wood preservative materials. [ABSTRACT FROM AUTHOR]