Abstract
Plant proteins contain bioactive peptides with functional properties and physiological activities. In the present work, the bioactive peptides produced during in vitro gastrointestinal digestion of soya protein isolate were investigated. Protein samples were subjected to simulated gastrointestinal digestion with a generation of permeate (<3 kDa) and retentate (>3 kDa) fractions. The permeate was analysed by nano-liquid chromatography electrospray ionisation tandem mass spectrometry (LC-nano ESI MS/MS) using a shotgun peptidomic approach, and the retentate was further digested with trypsin and analysed using a shotgun proteomic approach. Based on protein profile observed, the retentate was further tested for its potential antimicrobial activity by evaluating the inhibitory effect on E. coli growth. In the present study the peptidomic/proteomic characterisation of permeate and retentate fractions revealed the presence of bioactive peptides and proteins associated with antioxidant, ACE-inhibitory, anti-hypertensive and antimicrobial activities. The presence of potentially antimicrobial proteins in the retentate fraction is supported by a marked E. coli F18+ growth inhibitory activity of the same fraction. In particular, the growth inhibitory effect was significant from one until six hours of incubation with 0.65–2.6 mg/ml of in vitro digested soya. The obtained data confirmed that soya-based supplements may have potential beneficial effects after human consumption, and they may be re-cycled for animal nutrition in line with the circular economy concept. Highlights Soya-based supplements are relevant sources of bioactive molecules. Soya based supplements could be re-cycled for animal feeding considering the circular economy concept.
Highlights
A growing body of scientific evidence has revealed that many food proteins and peptides exhibit specific biological activities in addition to their established nutritional value (Fekete et al 2016; 2018)
The final hydrolysate obtained represents a pool of peptides and polypeptides resembling those generated during the physiological digestion of soya proteins
With regard to Angiotensin-Converting Enzyme (ACE) inhibitory activity, it has been reported (Giromini et al 2017) that this property was significantly reduced in soya permeate fractions compared to the undigested and to retentate fraction (>3kDa). These findings demonstrate that digestion may modulate protein bio-activities, such as those related to ACE inhibition
Summary
A growing body of scientific evidence has revealed that many food proteins and peptides exhibit specific biological activities in addition to their established nutritional value (Fekete et al 2016; 2018). Besides the well-demonstrated functional activity of milk peptides derived from the digestion of proteins (Giromini et al 2019a; Giromini et al 2019b; Politis and Theodorou, 2016 ), several plant proteins have demonstrated that they contain bioactive molecules beneficial for the health (Giromini et al 2017). Many bioactive peptides have already been isolated from soya proteins and previous studies have demonstrated their potential functional properties and physiological activities, such as antihypertensive, hypocholesterolaemic, antioxidant, and anticancer (Wang and De Mejia 2005).
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