Adeola M. Alashi

Antioxidant properties of Australian canola meal protein hydrolysates

Antioxidant activities of canola protein hydrolysates (CPHs) and peptide fractions prepared using five proteases and ultrafiltration membranes (1, 3, 5, and 10kDa) were investigated. CPHs had similar and adequate quantities of essential amino acids. The effective concentration that scavenged 50% (EC50) of the ABTS(+) was greatest for the <1kDa pancreatin fraction at 10.1μg/ml. CPHs and peptide fractions scavenged DPPH(+) with most of the EC50 values being <1.0mg/ml. Scavenging of superoxide radical was generally weak, except for the <1kDa pepsin peptide fraction that had a value of 51%. All CPHs inhibited linoleic acid oxidation with greater efficiency observed for pepsin hydrolysates. The oxygen radical absorbance capacity of Alcalase, chymotrypsin and pepsin hydrolysates was found to be better than that of glutathione (GSH) (p<0.05). These results show that CPHs have the potential to be used as bioactive ingredients in the formulation of functional foods against oxidative stress.

Antihypertensive and free radical scavenging properties of enzymatic rapeseed protein hydrolysates

In this study, rapeseed protein isolate (RPI) was digested with various proteases to produce rapeseed protein hydrolysates (RPHs), which were then separated into different peptide fractions (<1, 1-3, 3-5, and 5-10kDa) by membrane ultrafiltration. Membrane fractionation showed that peptides with sizes <3 kDa had significantly (p<0.05) reduced surface hydrophobicity when compared to the RPHs and peptide fractions with sizes >3 kDa. In contrast, the <3 kDa peptides showed significantly (p<0.05) higher oxygen radical scavenging ability when compared to the >3 kDa peptides and RPHs. In vitro inhibition of angiotensin I-converting enzyme (ACE) was significantly (p<0.05) higher for the Thermolysin, Proteinase K and Alcalase RPHs when compared to the pepsin+pancreatin (PP) and Flavourzyme RPHs. The Alcalase RPH had significantly (p<0.05) higher renin inhibition among the RPHs, while with the exception of Thermolysin, the 5-10 kDa peptide fraction had the least renin-inhibitory ability when compared to the <5 kDa peptide fractions. Oral administration (100mg/kg body weight) of the RPHs and RPI to spontaneously hypertensive rats (SHR) showed the Alcalase RPH to be the most effective in blood pressure (BP) reduction (∼24 mm Hg) while Proteinase K RPH was the least effective (∼5 mm Hg) after 8h. However, the PP RPH had the most prolonged effect with BP reduction of ∼20 mm Hg after 24h of oral administration. We conclude that the strong BP-lowering ability of Alcalase and PP RPHs could be due to high resistance of the peptides to structural degradation coupled with high absorption rate within the gastrointestinal tract.

A novel hemp seed meal protein hydrolysate reduces oxidative stress factors in spontaneously hypertensive rats.

This report shows the antioxidant effects of a hemp seed meal protein hydrolysate (HMH) in spontaneously hypertensive rats (SHR). Defatted hemp seed meal was hydrolyzed consecutively with pepsin and pancreatin to yield HMH, which was incorporated into rat feed as a source of antioxidant peptides. Young (8-week old) SHRs were divided into three groups (8 rats/group) and fed diets that contained 0.0%, 0.5% or 1.0% (w/w) HMH for eight weeks; half of the rats were sacrificed for blood collection. After a 4-week washout period, the remaining 20-week old SHRs were fed for an additional four weeks and sacrificed for blood collection. Plasma total antioxidant capacity (TAC) and superoxide dismutase (SOD), catalase (CAT) and total peroxides (TPx) levels were determined. Results showed that plasma TAC, CAT and SOD levels decreased in the older 20-week old SHRs when compared to the young SHRs. The presence of HMH in the diets led to significant (p < 0.05) increases in plasma SOD and CAT levels in both young and adult SHR groups; these increases were accompanied by decreases in TPx levels. The results suggest that HMH contained antioxidant peptides that reduced the rate of lipid peroxidation in SHRs with enhanced antioxidant enzyme levels and total antioxidant capacity.

Technological and Bioactive Functionalities of Canola Meal Proteins and Hydrolysates

Canola meal proteins have been credited with some technological food functional abilities, including foaming, water absorption, solubility, gelling, emulsifying, and foaming properties, despite the presence of other nonprotein moieties in the preparations studied to date. Unfortunately, these proteins have found limited practical use in food processing, presumably due to their poor solubility in aqueous systems at neutral pH. Consequently, canola meal proteins are undervalued as food ingredients. There is, however, high potential to improve the value of canola meal proteins via modification, especially by enzymatic hydrolysis to improve their solubility, and, hence, many of these functional properties. Enzymatic hydrolysis can also be employed to generate nutritionally functional hydrolysates and bioactive peptides. The most studied bioactive properties of canola protein hydrolysates was found to be the angiotensin-converting enzyme (ACE) inhibitor and antioxidant activities, whereas others such as the antimicrobial and anticancer properties have been less investigated. Therefore, this review looks into some of the studies carried out on canola proteins and gives an insight to the future research needs.

Enzyme inhibition kinetics and molecular interactions of patatin peptides with angiotensin I-converting enzyme and renin

In this work, the inhibitory effects of potato patatin-derived peptides Trp-Gly (WG) and Pro-Arg-Tyr (PRY) on angiotensin I-converting enzyme (ACE) and renin activities were investigated using kinetics, intrinsic fluorescence and molecular docking. The results indicated that PRY was a more potent ACE- and renin-inhibitory peptide than WG. Enzyme inhibition kinetics showed that WG and PRY inhibited ACE activity through mixed-type and competitive modes, respectively. The inhibitory mechanism of WG and PRY towards renin was determined to be mixed-type. PRY exhibited stronger affinity towards ACE and renin molecules, when compared to WG as determined by intrinsic fluorescence intensity. Molecular docking data confirmed that the higher inhibitory potency of PRY might be attributed to formation of more hydrogen bonds with the enzymes active site or non-active sites that distorted the configuration necessary for catalysis.

Inhibitory properties of bambara groundnut protein hydrolysate and peptide fractions against angiotensin‐converting enzymes, renin and free radicals

BACKGROUND An increased rate of high blood pressure has led to critical human hypertensive conditions in most nations. In the present study, bambara protein hydrolysates (BPHs) obtained using three different proteases (alcalase, trypsin and pepsin) and their peptide fractions (molecular weight: 10, 5, 3 and 1 kDa) were investigated for antihypertensive and antioxidant activities. RESULTS Alcalase hydrolysate contained the highest amount of low molecular weight (LMW) peptides compared to pepsin and trypsin hydrolysates. LMW peptides fractions (<1 kDa) exhibited the highest inhibitory activity against angiotensin-converting enzyme (ACE) for all the enzymes hydrolysates. For renin inhibition, alcalase hydrolysate showed the highest inhibition at 59% compared to other hydrolysates and their corresponding membrane fractions. The antioxidant power of bambara protein hydrolysates and peptide fractions was evaluated through the inhibition of linoleic acid peroxidation and ABTS scavenging activity. Among the hydrolysates, alcalase exhibited the highest inhibition of linoleic acid oxidation. Furthermore, all BPHs were able to scavenge ABTS•+ to a three-fold greater extent compared to the isolate. CONCLUSION BPH and LMW peptide fractions could potentially serve as useful ingredients in the formulation of functional foods and nutraceuticals against high blood pressure and oxidative stress.

Antihypertensive properties of aqueous extracts of vegetable leaf‐fortified bread after oral administration to spontaneously hypertensive rats

This study investigated the potential cardiovascular health benefits of leavened bread produced from wheat flour that contained 1%, 2% and 3% additions of leafy vegetable powders obtained from Amaranthus viridis (AO), Solanum macrocarpon (SM) or Telfairia occidentalis (TO). Dried breads were extracted with water at 60 °C followed by analysis for total polyphenolic content (TPC), as well as in vitro inhibitions of angiotensin-converting enzyme and renin activities. HPLC analysis of the bread extracts indicated the presence of mainly rutin, gallic acid, myricetin and caffeic acid. TPC of the vegetable-fortified breads was significantly (P < 0.05) higher (5.8–7.6 mg gallic acid equivalent, GAE/g) than that of control bread (5.5 mg GAE/g). Oral administration of 100 mg dried extract/kg body weight to spontaneously hypertensive rats led to reductions (up to 42 mmHg) in systolic, diastolic and mean arterial blood pressure in comparison with 20 mmHg for the control bread.

Antihypertensive properties of tilapia (Oreochromis spp.) frame and skin enzymatic protein hydrolysates

ABSTRACT Proteins from tilapia frame and skin can potentially be precursors of antihypertensive peptides according to the result of BIOPEP analyses. The aim was to generate peptides with inhibitory effects against angiotensin-converting enzyme (ACE) and renin from tilapia frame and skin protein isolates (FPI and SPI). The most active hydrolysate was then tested for blood pressure-lowering ability in spontaneously hypertensive rats (SHRs). Tilapia frame and skin protein hydrolysates (FPHs and SPHs) were respectively produced from FPI and SPI hydrolysis using pepsin, papain, or bromelain. The ACE-inhibitory activities of tilapia protein hydrolysates with varying degree of hydrolysis (DH) were evaluated. In order to enhance the activity, the hydrolysate was fractionated into four fractions (<1 kDa, 1–3 kDa, 3–5 kDa, and 5–10 kDa) and the one with the greatest ability to inhibit in vitro ACE and renin activities was subjected to oral administration (100 mg/kg body weight) to SHRs. Systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure (MAP), and heart rates (HR) were subsequently measured within 24 h. The pepsin-hydrolyzed FPH (FPHPe) with the highest DH (23%) possessed the strongest ACE-inhibitory activity (IC50: 0.57 mg/mL). Its <1 kDa ultrafiltration fraction (FPHPe1) suppressed both ACE (IC50: 0.41 mg/mL) and renin activities more effectively than larger peptides. In addition, FPHPe1 significantly (p < 0.05) reduced SBP (maximum −33 mmHg), DBP (maximum −24 mmHg), MAP (maximum −28 mmHg), and HR (maximum −58 beats) in SHRs. FPHPe1 showed both in vitro and in vivo antihypertensive effects, which suggest tilapia processing coproducts may be valuable protein raw materials for producing antihypertensive peptides.

Proteins From Canola/Rapeseed: Current Status

Abstract Canola/rapeseed (Brassica napus, Brassica rapa, and Brassica juncea of canola quality) is the world’s second-largest oilseed crop. The primary product of canola/rapeseed (C/RS) is vegetable oil (40% by seed weight) and the protein-rich meal (38% protein by meal weight) is a coproduct. Nutritionally, C/RS proteins are comparable with soybean and contain more S-amino acids than many other oilseed meals. Current knowledge on C/RS protein is extensive, however the main research emphasis in the past has been in the use of meal protein in animal feed rather than food-grade protein products. Customized processing interventions for C/RS are required to obtain a suitable protein for food use and current commercial oil extraction techniques amplify these challenges. To date, there has been limited effort to improve the C/RS protein quality or quantity through plant breeding compared to the efforts to improve oil quality and yield. The essential combination of economically competitive technologies, formulation of compatible food products and satisfactory scientific data for regulatory approval is needed for C/RS proteins to succeed as an ingredient in consumer foods.Canola/rapeseed (Brassica napus, Brassica rapa, and Brassica juncea of canola quality) is the world’s second-largest oilseed crop. The primary product of canola/rapeseed (C/RS) is vegetable oil (40% by seed weight) and the protein-rich meal (38% protein by meal weight) is a coproduct. Nutritionally, C/RS proteins are comparable with soybean and contain more S-amino acids than many other oilseed meals. Current knowledge on C/RS protein is extensive, however the main research emphasis in the past has been in the use of meal protein in animal feed rather than food-grade protein products. Customized processing interventions for C/RS are required to obtain a suitable protein for food use and current commercial oil extraction techniques amplify these challenges. To date, there has been limited effort to improve the C/RS protein quality or quantity through plant breeding compared to the efforts to improve oil quality and yield. The essential combination of economically competitive technologies, formulation of compatible food products and satisfactory scientific data for regulatory approval is needed for C/RS proteins to succeed as an ingredient in consumer foods.

Effects of canola proteins and hydrolysates on adipogenic differentiation of C3H10T/2 mesenchymal stem cells

This study assessed the ability of canola protein isolate (CPI) and enzymatic hydrolysates (CPHs) to inhibit adipogenic differentiation of C3H10T1/2 murine mesenchymal stem cells in vitro. Cell viability was maintained at concentrations of 60 μg/ml of sample. Cells treated with Alcalase hydrolysate demonstrated a higher reduction in anti-adipogenic differentiation through quantitation by oil-red O staining. qPCR analysis showed that CPI and CPH-treated cells significantly inhibited PPARγ expression, a key transcription factor involved in adipocyte differentiation, as evident in an ∼ 60-80% fold reduction of PPARγ mRNA. Immunofluorescence staining for PPARγ protein also showed a reduced expression in some treated cells when compared to differentiated untreated cells. The 50% inhibition concentration (IC50) of CPI, CPHs and their membrane ultrafiltration fractions on pancreatic lipase (PL) activity ranged between 0.75 and 2.5 mg/ml, (p < 0.05) for the hydrolysed and unhydrolysed samples. These findings demonstrate that CPI and CPHs contain bioactive components which can modulate in vitro adipocyte differentiation.