Pearl millet protein hydrolysates exhibiting effective in‐vitro antioxidant, antidiabetic and anti‐lipidemic properties as potential functional food ingredient

Abstract

Millets are well-known for protein with high nutritional value and a range of health benefits. Milletderived proteins can thus be a rich source of bioactive peptides with multiple bioactive properties. In this study three proteolytic enzymes, i.e. alcalase, bromelain, and chymotrypsin were used to generate pearl millet protein hydrolysates (PMPHs) and explored for multifunctional bioactive properties. Degree of hydrolysis (DH) ranged between 28.69% and 59.21% with maximum DH observed for PMPs hydrolysed with bromelain for 9 h. The PMPs digested with alcalase exhibited enhanced in-vitro anti-diabetic potential with greater inhibition towards α-amylase and dipeptidyl peptidase-IV (DPP-IV) with IC 50 inhibitory concentration of 5.06 and 3.44 μg mL −1 , respectively. Alcalase PMPHs demonstrated the strongest ABTS radical scavenging activity (976 mM TEAC) while chymotrypsin-generated PMPHs showed significant scavenging of DPPH free radicals (222.3 mM TEAC). In addition, bromelain-treated hydrolysates displayed the highest α-glucosidase inhibitory activity (6.71 μg mL −1 ) and Ferric reducing anti-oxidant power (585.7 mM TEAC). Moreover, PMPHs generated by alcalase showed potential anti-lipidemic activity by inhibiting pancreatic lipase and cholesteryl esterase with maximum IC 50 values of 3.46 and 3.61 μg mL −1 , respectively. These findings suggest that PMPs could be used as a potential source for bioactive hydrolysates with improved anti-diabetic, anti-lipidemic, and anti-oxidant activities.

Improved Bioactivity and Functional Qualities of Millet Protein Enzyme Hydrolysates by Ultrasonication

“…This could be due to cavitational waves that induce synergistic effects on the structural modifications in proteins, which leads to the exposure of buried active antioxidant sites within the protein structure and makes them more accessible for interactions with free radicals, like DPPH, compared to the parent protein . Also, the scavenging activity is aided by their abundance of amino acid peptide residues, which may transfer the electrons to free DPPH radicals at physiological pH and contribute to their antioxidant activities . In addition, US followed by protease hydrolysis can break the disulfide bonds in the protein, leading to the release of free SH groups.…”

“…The bromelain-derived UBMPHs resulted in an increase in CEase inhibition activity as the sonication time increased from 5 to 15 min (IC 50 values = 0.54 to 0.34 mg/mL) but decreased after that; this might be due to the degradation of active peptides, which inhibit the CEase enzyme, and were unavailable to bind CEase active sites. Recently, previous studies reported that pearl millet hydrolysates 81 and amaranth protein hydrolysates 82 show higher CEase inhibition activity than intact protein. Moreover, Soares et al, 2015, 83 reported that the amaranth protein peptides showed inhibitors of HMG-CoA reductase, resulting in a hypocholesterolaemia effect.…”

“…82 In addition, one study reported that trypsin and alcalase-hydrolyzed pea protein hydrolysates showed high PL inhibition activities at 3.95 and 3.92 mg/ mL 31 , respectively. Recently, Mudgil et al, 2022 81 reported pearl millet hydrolysates generated by alcalase, bromelain, and chymotrypsin. They reported that alcalase hydrolysates (3.46 μg/mL) after 6 h of reaction time had low IC 50 values, indicating a higher PL inhibition activity.…”

“…67 Also, the scavenging activity is aided by their abundance of amino acid peptide residues, which may transfer the electrons to free DPPH radicals at physiological pH and contribute to their antioxidant activities. 81 In addition, US followed by protease hydrolysis can break the disulfide bonds in the protein, leading to the release of free SH groups. These SH groups can directly react with free radicals and neutralize them.…”

Advances in the novel and green-assisted techniques for extraction of bioactive compounds from millets: A comprehensive review

“…The seed coat of millet contains the highest concentration of bioactive compounds, while the starchy endosperm has a relatively low concentration [ 8 , 9 ]. The extraction of bioactive compounds is an important process in food processing [ 10 ] as it allows for the isolation and concentration of compounds offering antioxidant and anti-inflammatory activities, which can help to reduce the risk of chronic diseases such as cancer, cardiovascular disease, and diabetes [ [11] , [12] , [13] ].…”