Flavonoid tannins linked to long carbohydrate chains - MALDI-TOF analysis of the tannin extract of the African locust bean shells

Neré (Parkia biglobosa) or African locust bean tree tannins have been extracted in two different ways: (i) by an artisanal maceration method and (ii) by a commercial-like extraction in presence of bisulfite. The type of oligomers obtained in the two cases were rather different. Mostly polyphenolic oligomers are present in the case of the commercial like extraction, while for the artisanal maceration technique the unusual presence of long carbohydrate residues attached to the flavonoids were obtained. MALDI-TOF analysis showed short flavonoid oligomers linked to chains presenting up to 22 carbohydrate residues. Some stilbenes were also noticed in the extracts. These differences in the extracts obtained by different methods indicates that an extraction procedure needs to be chosen according to the final use the tannin extract is destined to.