Aryl glycosidases from Lactobacillus plantarum increase antioxidant activity of phenolic compounds

Glycosidases have great relevance in polyphenols, since their bioavailability is enhanced by these enzymatic activities. Glycosylated phenolic compounds are deglycosylated either in tissues or by the colonic microbiota. Lactobacillus plantarum is a widespread lactic acid bacteria commonly found in many fermented food products and in the gastrointestinal tract, some strains of which are employed as probiotics. The presence of glycosidase activities was assayed in L. plantarum strains isolated from different origins. The analyzed strains presented hydrolytic activity against α- and β-d-glucopyranoside and β-d-galactopyranoside. The latter activity could be related to the presence of a β-galactosidase encoding-gene present in all the L. plantarum strains analyzed. Glycosylated food phenolics, such as quercetin glucoside, phloridzin, esculin, salicin, and daidzin were deglycosylated by cell cultures or by cell extracts from L. plantarum CECT 748T as demonstrated by HPLC analysis. In this study was clearly demonstrated for the first time that the deglycosylation of specific aryl glycosides by L. plantarum was associated with an increase in their antioxidant activity measured by DPPH and SOD methods. Therefore, in addition to the improvement of their bioavailability, the presence of glycosidase activities on L. plantarum strains increases the antioxidant activity of glycosylated phenolic compounds.