An arabinan isolated from the antioxidant active fraction of wild blackthorn fruits (Prunus spinosa L.)

Despite the many health benefits of wild blackthorn fruits, their use is negligible and little explored. Preliminary results suggest that this fruit is a rich source of natural antioxidants. Antioxidant active fraction, extracted from wild blackthorn fruits by cold water extraction (Cw), was subjected to ion-exchange chromatography, which gave ten fractions after a successive elution with water, sodium chloride and sodium hydroxide solutions. Fraction eluted by water contained an arabinan of a low molecular weight (Mw = 5000). Its chemical and spectroscopic studies have revealed a highly branched structure with backbone composed of 1,5-linked alpha-L- arabinofuranose residues; about 76% of them are branched dominantly through O3 and much less through O2, however, some arabinose units (similar to 8%) were fully branched. In addition to terminal alpha-L-Araf, the presence of beta-L-Araf unit was also identified in blackthorn L-arabinan. Antioxidant activity tests of Cw ion exchange fractions revealed significant effects only of fractions eluted with 1 M sodium chloride (6F) and sodium hydroxide (7F) solutions, while phenolic free arabinan did not possess this effect. Phenolic compounds linked via alpha-L-arabinosyl side chains appear to be responsible for the antioxidant effect of two Cw fractions.