Utilization of hardened Phaseolus lunatus beans as a source of 2 naturally occurring bioactive peptides

Abstract

Hardened beans are rejected by consumers and frequently used as animal feed despite their unchanged nutritional content afterhardening. Particularly, hardened beans remain a rich source of protein and carbohydrates in a hungry world. There are several studies describing encrypted bioactive peptides; however, little is known about naturally occurring peptides and their functionalities. In this study, naturally occurring peptides from hardened Phaseolus lunatus were extracted, partially purified and examined regarding their biological potential. Extractor solutions were tested to obtain the maximum yield and antioxidant activity. The most nonpolar was the more effective for obtaining antioxidant peptides (DPPH -962±29 and FRAP -2567±83 μmol Trolox/mg protein). Treatment for 30 minutes/90 ºC increased 2.6-fold (2497 μmol Trolox/mg protein) the antioxidant activity by DPPH and 1.2-fold (3149 μmol Trolox/mg protein) the FRAP assay. Antioxidant peptides in the <3kDa-fraction resisted gastric/intestinal digestion and presented anti-peroxidative activity close to the BHT. Finally, peptides presented vasorelaxant activity in the range of 30% (F<3 kDa) and 17% (hydrolyzed F<3 kDa) and ACE-inhibitory activity in the range of 15% (F<3 kDa) and 85% (hydrolyzed F<3 kDa).