Biotransformation of common bean and wheat flavonoid glycosides by Lactic Acid Bacteria

The human gut is populated by an array of bacterial species, which develop important metabolic functions, with a marked effect on the nutritional and health status of the host. A relevant health aspect regards the interaction between nutrients introduced with the diet and beneficial gut microrganisms, in particular Bidifobacterium spp. and Lactobacillus spp. Flavonoids are biologically active polyphenols present in legumes and cereals with high antioxidant properties and demonstrated role in the prevention of cardiovascular diseases and cancer. Flavonoids are mainly present in foods as O-glycosides, whereas the biological activity is generally ascribed to the aglyconic moiety. Generally, intestinal enzymes do not possess the -glycosidase activity able to hydrolyze the bond between the sugar moiety and the bioactive compound thus avoiding its uptake and subsequent health benefits. However, for some human intestinal Bifidobacterium species -glycosidase activity on bean flavonoids has been described (Marotti et al. 2007). The aim of the present research is to extend the monitoring of -glycosidase activity to lactic acid bacteria (LAB) commonly used in food biotechnology and to evaluate their capability of metabolizing bean and wheat flavonoids. Fifteen strains of LAB, belonging to the species: L. fermentum, L. buchneri, L. fructivorans, L. helveticus , L. acidophilus, L. plantarum, L. kefiri, L. jugurti, L. lactis, L. bulgaricus, have been included in this research . The maximal -glycosidase activity was observed for strains belonging to the species L. buchneri, L. acidophilus and L. plantarum. Further studies are in progress aimed at evaluating the capability of the selected strains of metabolizing typical legume and wheat glycosilated flavonoids. Moreover, the capability of these strains of metabolizing the flavonoids present both in common bean seed and seedling extracts and wheat fiber extracts will be assayed. The research will also include some C-glycosilated flavonoids typically present in these plant sources and particular recalcitrant to hydrolysis. The strains showing the highest activity are potential good candidates for developing functional foods. Marotti et al. 2007 J Agric Food Chem. 55: 3913-3919