Effect of Protease Type and Peptide Size on the In Vitro Antioxidant, Antihypertensive and Anti-Diabetic Activities of Eggplant Leaf Protein Hydrolysates

Abstract

Solanum macrocarpon (eggplant) leaf protein isolate (ELI) was hydrolyzed using four different enzymes to produce hydrolysates from alcalase (AH), chymotrypsin (CH) pepsin (PH) and trypsin (TH). CH had an overall stronger antioxidant property and was separated using ultrafiltration membranes into <1, 1–3 and 3–5 kDa peptide fractions. Gel-permeation chromatography confirmed conversion of the ELI (average of 22 kDa) into protein hydrolysates that contained smaller peptides (<6 kDa). A total of 23 peptides consisting of tri and tetrapeptides were identified from the CH, which is a wider spectrum when compared to seven for AH and four each for TH and PH. CH exhibited stronger scavenging activities against DPPH and hydroxyl radicals. CH and TH exhibited the strongest inhibitions against angiotensin-converting enzyme. In contrast, AH was the strongest inhibitor of α-amylase while AH and PH had strong inhibitory activities against α-glucosidase when compared with other hydrolysates. Ultrafiltration fractionation produced peptides that were stronger (p < 0.05) scavengers of DPPH, and hydroxyl radicals, in addition to better metal-chelating and enzyme inhibition agents. The study concluded that the eggplant protein hydrolysates and the UF fractions may find applications in tackling oxidative stress-related diseases and conditions involving excessive activities of the metabolic enzymes.

Influence of ultrasonic pretreatment on structural properties and biological activities of lupin protein hydrolysate

“…The hydrolysate samples showed significantly (P < 0.05) higher inhibitory effects against the carbohydrase than LPI, suggesting that antidiabetic potentials of lupin protein can be enhanced by enzymatic hydrolysis. Proteolysis is known to facilitate the release of peptides with various improved inhibitory effects towards these enzymes in comparison with the original native proteins (Famuwagun et al, 2021).…”

“…The use of protein hydrolysate as a functional ingredient is becoming more popular because of the several physiological functions associated with bioactive peptides (BP) present in them. For instance, it has been documented that food protein-derived peptides can deliver potential benefits in the management of several chronic diseases, including hypertension and diabetics (Aluko, 2015;Famuwagun et al, 2021). Plant (soya bean, lentil, chickpea) and animal-based (eg milks, fish, egg) proteins contain distinct peptide sequences which are inactive within the protein matrix and only become active when cleaved, mostly during in vitro enzymatic hydrolysis (Aluko, 2018).…”

“…and known to have broad specificity to hydrophobic amino acids (Gao et al, 2014). In addition to the enzyme type, other factors such as molecular weight, degree of hydrolysis, peptide sequence, protein source and type of treatment applied to protein before hydrolysis can also influence the biological activities of protein hydrolysates (Fadimu et al, 2021;Famuwagun et al, 2021).…”

Purification, Identification and Molecular Docking of Novel Antioxidant Peptides from Walnut (Juglans regia L.) Protein Hydrolysates

“…DH is a measure of the rate of protein hydrolysis and captures the amount of peptide bond breakage in the protein [ 20 ]. The choice of the enzyme is key in the proteolytic process, which determines the location and number of hydrolyze peptide bonds and affects the reaction rate, yield and biological activity of the final product.…”

Albumin from Erythrina edulis (Pajuro) as a Promising Source of Multifunctional Peptides

“…In the case of α-glucosidase inhibitory activity, gastrointestinal digests from quinoa protein showed and IC 50 value of 1.81 mg protein/mL [ 49 ], and Alcalase hemp seed proteins hydrolyzates reached 50% enzyme inhibition at concentrations higher than 5 mg/mL [ 50 ]. A recent study reported inhibitory values of 38.9% (α-amylase) and 48.8% (α-glucosidase) for eggplant leaf protein hydrolyzates at 500 µg hydrolyzate/mL [ 51 ].…”