Comparative biological evaluation and identification of multifunctional endogenous and exogenous bioactive peptides in different matured Izmir Tulum cheeses

Bioactive peptides redefine health and disease by triggering unique biological functions in the body. The aim of this study was to evaluate and identify the endogenous and exogenous peptides (in vitro gastrointestinal digestion) of 360-day ripened Izmir Tulum cheese manufactured using cow, sheep, and goat milk. Peptide extracts from Izmir Tulum cheeses were found to have DPP-IV inhibitory, deglycation, antioxidant, metal chelating, and ACE-inhibitory activity. After the activity guided purification of peptide extracts were performed by HPLC, 8 peptide fractions were selected according to their biological activity, and the peptide sequence of each peptide were identified by mass spectrometry. It was observed that the use of different types of milk in the manufacture of Izmir Tulum cheese affects peptide diversity, that endogenous and exogenous peptides had a wide range of potential biological activities, and that new bioactive peptides were obtained from Izmir Tulum cheese. The potential peptide sequences obtained from the identified fractions ETFHPLKHQ, EVVPGPFPQ, and TLGLHTPK are the first peptide sequences that do not overlap with sequences published in the literature. In conclusion, these endogenous and exogenous peptides of Izmir Tulum cheeses have significant biological activities associated with type 2 diabetes, deglycation, antioxidants, and metal chelating agents to support the immune system, and ACE-inhibitory effects to treat hypertension. These new peptides could open a new avenue for the noval peptide-based drug and contribute to therapeutic applications.