Production and evaluation of ellagitannase activity using a pure geraniin substrate

Ellagitannins biodegradation produces ellagic acid, a high bioactive compound. An enzyme called ellagitannase has been proponed as the responsible of biodegrading ellagitannins, but the mechanisms have not been completely cleared. The aim of this work was to produce and purify partially an enzymatic extract able to biodegrade ellagitannins and test the enzymatic activity against a pure ellagitannin substrate (geraniin). Enzymatic extract was produced by solid-state fermentation using rambutan ellagitannins as substrate and Aspergillus niger GH1 as microorganism. Enzymatic extract was partially purified by dialysis and ultrafiltration and β-glucosidase, α-L-arabinofuranosidase and ellagitannase activities were tested. Ellagitanase activity was also tested using pure geraniin as substrate. Values of enzymatic activity after partial purification were obtained for the three enzymes tested, but the only inducible enzyme produced by the presence of ellagitannins was ellagitannase. Finally, the enzymatic assay using pure geraniin as substrate proved that this pure compound was effectively biodegraded into two compounds: dimers of tergallagic-O-hexoside and ellagic acid.