Role of Amaranthus caudatus (kiwicha) protein as source of multifunctional peptides

Abstract

[Introduction]: The multifactorial origin of many chronic diseases provides a new framework for the development of multifunctional foods. Bioactive peptides have become very popular because of their demonstrated multiple activities. No data on the potential role of Amaranthus caudatus (kiwicha) proteins as source of bioactive peptides have been reported. [Methods]: A kiwicha protein concentrate was characterized by gel electrophoresis (SDS-PAGE) and subjected to gastrointestinal digestion simulating physiological conditions. The gastric and gastroduodenal digests and the peptidic fractions lower and higher than 5 kDa were analyzed by their antioxidant, angiotensin I-converting enzyme (ACE), dipeptidyl peptidase IV (DPP-IV), α-amylase, and colon cancer cells viability inhibitory activities. Peptides contained in the most active digest were identified by liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). [Results]: The sequential incubation with pepsin and pancreatin resulted in the total degradation of kiwicha proteins. Gastric digest showed higher ACE inhibitory activity while 60 minutes gastroduodenal digest showed the highest antioxidant, dipeptidyl peptidase IV (DPP-IV), α-amylase, and Caco-2 cell viability inhibitory activities. Peptides > 5 kDa were more effective inhibiting colon cancer 32 cell viability whereas peptides < 5 kDa were mainly responsible for the antioxidant, ACE, DPP-IV, and α-amylase inhibitory activities. Thirteen peptides were identified in the most active gastroduodenal digest. Among them, and according to their structure, sequences FLISCLL, SVFDEELS, and DFIILE, might be responsible for the multifunctional effects observed. [Conclusions]: The role of kiwicha proteins as source of multifunctional peptides released under in vitro conditions simulating gastrointestinal digestion is confirmed. Thus, these proteins might be used as ingredients for functional foods to prevent and/or manage chronic diseases related to oxidative stress, hypertension and/or diabetes.