Characterization of bioactive peptides released during the fermentation of amaranth seeds with their endophytic bacteria

Introduction

Increasing interest has been taken in the therapeutic potential of Bioactive Peptides (BAPs), which are released from native proteins through hydrolysis. A promising method for breaking down food proteins is fermenting high-protein grains and seeds. To date, the application of fermentation of amaranth seeds with their endophytic microorganisms to produce BAPs has not been explored. Therefore, this study aimed to characterize the peptidome of fermented amaranth seeds and evaluate the potential bioactivity of the released peptides.

Methods

Amaranth seed protein hydrolysis was performed by spontaneous fermentation at a 1:2.5 solid-liquid ratio for 72h. Extracted peptides were screened for bioactivity using in vitro assays, and peptidomic analysis was conducted by using LC-MS/MS.

Results and Discussion

Amaranth flour fermentation resulted in peptide enrichment below 3.5 kDa with a total protein degradation percent of 79.5%. More than 250 unique peptides were identified and tested in BIOPEP-UWM to assess their potential bioactivities. The most prevalent was the dipeptide Glu-Glu, which has been linked to neuroprotective, antihypertensive, anticancer, and antibacterial activities. Furthermore, released peptides exhibited DPPH–inhibitory activity in vitro with IC₅₀ values of 0.96 ± 0.1 mg/mL, 1.06 ± 0.1 mg/mL, and 1.36 ± 0.1 mg/mL for peptides under 3 kDa, below 3kDa, and the whole peptide population, respectively.

Conclusions

Data show that spontaneous fermentation of amaranth seeds is an effective and reliable method for producing BAPs. The assay to test the neuroprotective and antihypertensive potential of these peptides is in progress.