Preparation of bioactive peptides with high angiotensin converting enzyme inhibitory activity from winged bean [Psophocarpus tetragonolobus (L.) DC.] seed

Protein Hydrolysate from Underutilized Legumes: Unleashing the Potential for Future Functional Foods

Proteins play a vital role in human development, growth, and overall health. Traditionally, animal-derived proteins were considered the primary source of dietary protein. However, in recent years, there has been a remarkable shift in dietary consumption patterns, with a growing preference for plant-based protein sources. This shift has resulted in a significant increase in the production of plant proteins in the food sector. Consequently, there has been a surge in research exploring various plant sources, particularly wild, and underutilized legumes such as Canavalia, Psophocarpus, Cajanus, Lablab, Phaseolus, and Vigna, due to their exceptional nutraceutical value. This review presents the latest insights into innovative approaches used to extract proteins from underutilized legumes. Furthermore, it highlights the purification of protein hydrolysate using Fast Protein Liquid Chromatography. This review also covers the characterization of purified peptides, including their molecular weight, amino acid composition, and the creation of three-dimensional models based on amino acid sequences. The potential of underutilized legume protein hydrolysates as functional ingredients in the food industry is a key focus of this review. By incorporating these protein sources into food production, we can foster sustainable and healthy practices while minimizing environmental impact. The investigation of underutilized legumes offers exciting possibilities for future research and development in this area, further enhancing the utilization of plant-based protein sources.

Produksi Hidrolisat Protein Kacang Koro Benguk dengan Aktivitas Penghambat Kerja Enzim Pengkonversi Angiotensin melalui Kombinasi Fermentasi dan Hidrolisis Enzimatik

Mucuna bean (Mucuna pruriens L.) is a legume having high protein content which has the potential as a source of bioactive peptides. One of the bioactive peptides is an angiotensin-converting enzyme (ACE) inhibitor, thus, mucuna beans might be used as a potential source of antihypertensive compounds. This study aimed to increase the functionality of proteins from mucuna beans as ACE inhibitors using a combination of fermentation and enzymatic hydrolysis followed by membrane filtration. The mucuna beans were fermented for 0, 24, 48, 96, and 144 h. The highest ACE inhibitory activity of 54.37%, was obtained by fermentation of the beans at 48 h, with a protein content of 20.82 mg/mL. The 48 h fermented mucuna beans were further hydrolyzed using alcalase or neutrase and subsequently filtered with UF membranes having 20,10 and 5 kDa cut-off. The enzymatic hydrolysis followed by membrane filtration increased the ACE inhibitory activity of mucuna beans. The neutrase hydrolysates resulting from 5 kDa membrane filtration showed the best ACE inhibitory activity (62.96% with a protein content of 10.39 mg/mL). A combination of fermentation and enzymatic hydrolysis followed by filtration using UF-membrane was able to produce ACE inhibitory peptides from mucuna beans. The potential of mucuna beans peptides as ACE inhibitors was due to the presence of negatively charged amino acid residues such as Asp and Glu, positively charged amino acids such as Arg and Lys, and hydrophobic amino acids such as Val, Leu, Ala, and Ile.

Next-generation nutraceuticals: bioactive peptides from plant proteases

Bioactive peptides are short and specific fragments of proteins with a wide range of biological activities that provide health benefits to the host. These natural peptides are safe and nontoxic and do not show any side effects. Nowadays, the production and characterization of bioactive peptides have been a key area of research as they show great potential as nutraceuticals and functional foods. Thus, bioactive peptides are considered next-generation therapeutic agents that can replace pharmaceutical products with profound adverse effects in the near future. So far, proteolytic hydrolysis has been used as the method of choice for the large-scale production of bioactive peptides. Studies have reported that peptides with specific characteristics can be generated using a particular type of protease. Microbial proteases are the predominantly used ones because of the ease in their production and purification. However, recently, plant proteases have gained a renewed interest as they offer diversity and better specificity compared with other proteases. This review highlights the potential of plant proteases for the production of bioactive peptides and also describes the benefits of bioactive peptides as nutraceuticals.

Biologically Synthesized Peptides Show Remarkable Inhibition Activity against Angiotensin-Converting Enzyme: A Promising Approach for Peptide Development against Autoimmune Diseases

Angiotensin-converting enzyme (ACE) regulates several biological functions besides its vital role in immune functions. ACE is elevated in immune cells in inflammatory diseases including atherosclerosis, granuloma, chronic kidney disease, and also autoimmune diseases, like multiple sclerosis, rheumatoid arthritis, and type I diabetes. No significant information prevails in the literature regarding the isolation, identification, and profiling of potential ACE inhibitory peptides. In the present study, indigenous crop varieties like seeds (peanut, corn, oat, sunflower, chickpea, parsley, cottonseed, papaya, sesame, and flaxseed) were used to evaluate their ACE inhibition activity. Variables including hydrolysis time, enzyme-to-substrate ratio (E/S), pH, and temperature were standardized to acquire the most suitable and optimum ACE inhibition activity. Seeds of cotton, chickpea, and peanuts displayed remarkably maximum ACE inhibition activity than other plants. The study disclosed that maximum ACE inhibitory activity (86%) was evaluated from cottonseed at pH 8.0, temperature of 45°C, hydrolysis time of 2 hrs, and enzyme to the substrate (E/S) ratio of 1 : 5 followed by peanuts (76%) and chickpea (55%). SDS-PAGE confirmed that vicilin protein is present in cottonseed and peanut seed while cruciferin and napin proteins are present in chickpeas. LC-MS/MS analysis disclosed potential novel peptides in hydrolyzed cottonseed that can be ascribed as potential ACE inhibitors which have never been reported and studied earlier. The current study further showed that cottonseed peptides due to their promising ACE inhibitory activity can be a valuable source in the field of ACE inhibitor development.

Orphan Crops: A Best Fit for Dietary Enrichment and Diversification in Highly Deteriorated Marginal Environments

Orphan crops are indigenous and invariably grown by small and marginal farmers under subsistence farming systems. These crops, which are common and widely accepted by local farmers, are highly rich in nutritional profile, good for medicinal purposes, and well adapted to suboptimal growing conditions. However, these crops have suffered neglect and abandonment from the scientific community because of very low or no investments in research and genetic improvement. A plausible reason for this is that these crops are not traded internationally at a rate comparable to that of the major food crops such as wheat, rice, and maize. Furthermore, marginal environments have poor soils and are characterized by extreme weather conditions such as heat, erratic rainfall, water deficit, and soil and water salinity, among others. With more frequent extreme climatic events and continued land degradation, orphan crops are beginning to receive renewed attention as alternative crops for dietary diversification in marginal environments and, by extension, across the globe. Increased awareness of good health is also a major contributor to the revived attention accorded to orphan crops. Thus, the introduction, evaluation, and adaptation of outstanding varieties of orphan crops for dietary diversification will contribute not only to sustained food production but also to improved nutrition in marginal environments. In this review article, the concept of orphan crops vis-à-vis marginality and food and nutritional security is defined for a few orphan crops. We also examined recent advances in research involving orphan crops and the potential of these crops for dietary diversification within the context of harsh marginal environments. Recent advances in genomics coupled with molecular breeding will play a pivotal role in improving the genetic potential of orphan crops and help in developing sustainable food systems. We concluded by presenting a potential roadmap to future research engagement and a policy framework with recommendations aimed at facilitating and enhancing the adoption and sustainable production of orphan crops under agriculturally marginal conditions.

Techniques, perspectives, and challenges of bioactive peptide generation: A comprehensive systematic review

Due to the digestible refractory and absorbable structures of bioactive peptides (BPs), they could induce notable biological impacts on the living organism. In this regard, the current study was devoted to providing an overview regarding the available methods for BPs generation by the aid of a systematic review conducted on the published articles up to April 2019. In this context, the PubMed and Scopus databases were screened to retrieve the related publications. According to the results, although the characterization of BPs mainly has been performed using enzymatic and microbial in-vitro methods, they cannot be considered as suitable techniques for further stimulation of digestion in the gastrointestinal tract. Therefore, new approaches for both in-vivo and in-silico methods for BPs identification should be developed to overcome the obstacles that belonged to the current methods. The purpose of this review was to compile the recent analytical methods applied for studying various aspects of food-derived biopeptides, and emphasizing generation at in vitro, in vivo, and in silico.

Psophocarpus tetragonolobus: An Underused Species with Multiple Potential Uses

Natural products, particularly those extracted from plants, have been used as therapy for different diseases for thousands of years. The first written records on the plants used in natural medicine, referred to as "medicinal plants", go back to about 2600 BC. A thorough and complete understanding of medicinal plants encompasses a multiplex of overlapping and integrated sciences such as botany, pharmacognosy, chemistry, enzymology and genetics. Psophocarpus tetragonolobus, a member of Fabaceae family also called winged bean, is a perennial herbaceous plant characterized by its tuberous roots and its winged pod twinning and a perennial legume rich in proteins, oils, vitamins and carbohydrates. Besides nutrients, winged bean also contains bioactive compounds that have therapeutic activities like anti-oxidant, anti-inflammatory, antinociceptive, antibacterial, antifungal, antiproliferative and cytotoxic activity, a few of which already been reported. This plant can also be used as a medicinal plant for future benefits. With this concept in mind, the present review is designed to shed the light on the interests in the various phytochemicals and pharmacological pharmacognostical aspects of Psophocarpus tetragonolobus.

Membrane-based preparative methods and bioactivities mapping of tempe-based peptides

This study was aimed to produce bioactive peptides from optimally fermented tempe, and map their overall bioactivities. There were three preparative methods utilized for producing tempe-based peptides, such as water-facilitated extraction, alcalase, and papain hydrolysis, and in combination with membrane filtration. Fermenting soybean at 144 h was selected as the optimum time based on protein content and degree of hydrolysis. Through SDS-PAGE analysis, an increased degree of hydrolysis with longer fermentation time was confirmed. The best preparative method for producing bioactive peptides was through papain hydrolysis and followed by 5 kDa membrane filtration. By this, the enhancement was distinct for antioxidant activity, ACE-, α-glucosidase-, and Kunitz trypsin-inhibitory activity. The annotated peptide sequences resulting from Nano LC Ultimate 3000 Series System tandem Q Exactive™ Hybrid Quadrupole-Orbitrap™ Mass Spectrometer were matched with the BIOPEP database. The major bioactivities of tempe peptides obtained were as an ACE inhibitor, antioxidant, and antithrombotic.

Antioxidant, Angiotensin-Converting Enzyme Inhibitory Properties and Blood-Pressure-Lowering Effect of Rice Bran Protein Hydrolysates

This research aimed to investigate the biological properties of different hydrolysates derived from industrial and laboratory defatted rice bran proteins. Industrial and laboratory defatted rice bran protein concentrates were hydrolyzed with alcalase or flavorzyme. The degree of hydrolysis (DH), oxygen radical absorbance capacity (ORAC), reducing power, total phenolic compounds (TPC), and angiotensin-converting enzyme (ACE) inhibitory activity, were determined in the hydrolysates and the molecular fractions lower than 3 kDa. Systolic blood pressure (SBP) was measured using the tail-cuff method before and after oral administration of 80 mg/kg of different rice bran protein hydrolysate (RBPH) fractions lower than 3 kDa in male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. The highest values of in vitro antioxidant activity and TPC were observed in RBPH with alcalase defatted by industry (RBPH2A), and, in all cases, these bioactivities were higher in the molecular fractions lower than 3 kDa. Once again, fractions lower than 3 kDa obtained with alcalase showed a potent ACE inhibitory activity (RBPH1A<3 and RBPH2A<3). The administration of RBPH1A<3 caused a significant decrease in the SBP in SHR, where the maximum decrease was reached at 8 h after administration. SBP in WKY rats was not modified after the administration of RBPH1A<3. These results suggest that the rice bran protein hydrolysates obtained from industry after treatment with alcalase could be an interesting source of bioactive peptides, with potential action on hypertension and other related pathologies.

Response Factorial Design Analysis on Papain-Generated Hydrolysates from Actinopyga lecanora for Determination of Antioxidant and Antityrosinase Activities

Actinopyga lecanora (A. lecanora) is classified among the edible species of sea cucumber, known to be rich in protein. Its hydrolysates were reported to contain relatively high antioxidant activity. Antioxidants are one of the essential properties in cosmeceutical products especially to alleviate skin aging. In the present study, pH, reaction temperature, reaction time and enzyme/substrate ratio (E/S) have been identified as the parameters in the papain enzymatic hydrolysis of A. lecanora. The degree of hydrolysis (DH) with antioxidant activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays were used as the responses in the optimization. Analysis of variance (ANOVA), normal plot of residuals and 3D contour plots were evaluated to study the effects and interactions between parameters. The best conditions selected from the optimization were at pH 5.00, 70 °C of reaction temperature, 9 h of hydrolysis time and 1.00% enzyme/substrate (E/S) ratio, with the hydrolysates having 51.90% of DH, 42.70% of DPPH activity and 109.90 Fe²⁺μg/mL of FRAP activity. The A. lecanora hydrolysates (ALH) showed a high amount of hydrophobic amino acids (286.40 mg/g sample) that might be responsible for antioxidant and antityrosinase activities. Scanning electron microscopy (SEM) image of ALH shows smooth structures with pores. Antityrosinase activity of ALH exhibited inhibition of 31.50% for L-tyrosine substrate and 25.40% for L-DOPA substrate. This condition suggests that the optimized ALH acquired has the potential to be used as a bioactive ingredient for cosmeceutical applications.

Two novel ACE inhibitory peptides isolated from longan seeds: purification, inhibitory kinetics and mechanisms

Angiotensin converting enzyme (ACE) inhibition offers a useful means of managing hypertension, because ACE inhibitors (ACEIs) are known to serve as agents with antihypertensive properties in addition to generating positive metabolic and cardioprotective outcomes. However, current ACEIs are linked to adverse consequences, and so there is a requirement for effective but safer compounds, which might be achieved through chemical synthesis or the isolation of naturally obtained bioactive molecules. Protein hydrolysates with ACEI activity can be produced by the combined pepsin and pancreatin proteolysis (to mimic gastrointestinal digestion) of longan seed protein. This study examined longan seed protein hydrolysates, obtained from a sequential 3 h digestion with pepsin and then pancreatin. The resulting hydrolysate underwent sequential ultrafiltration membrane fractionation with a 10, 5, and 3 kDa molecular weight cut-off (MWCO). The permeate derived from the <3 kDa MWCO demonstrated the highest ACEI activity. This permeate subsequently underwent separation by reverse-phase high performance liquid chromatography to give the main fractions on the basis of differing elution times. The ACEI IC50 values for these fractions were then identified. Quadrupole time-of-flight tandem mass spectrometry was employed to determine the peptide mass for the major peak (F 5), which was shown to be Glu-Thr-Ser-Gly-Met-Lys-Pro-Thr-Glu-Leu (ETSGMKPTEL) and Ile-Ser-Ser-Met-Gly-Ile-Leu-Val-Cys-Leu (ISSMGILVCL). These two peptides were stable over a temperature and pH range of -20 to 90 °C and 2-12, respectively, for 60 min. From the Lineweaver-Burk plot, both peptides inhibited ACE non-competitively. Molecular docking simulation of the peptides with ACE supported the formation of hydrogen bonds by the peptides with the ACE active pockets. This research indicates that it may be possible to use both of these peptides or longan seed protein hydrolysates in order to create ingredients for functional foods, or to produce pharmaceutical products, capable of lowering hypertension.

Nutrient and Antinutrient Composition of Winged Bean (Psophocarpus tetragonolobus (L.) DC.) Seeds and Tubers

Many people in sub-Saharan Africa suffer from protein malnutrition; this results in negative health and economic impacts. Winged bean (Psophocarpus tetragonolobus (L.) DC.) is a tropical underutilized legume with beneficial nutritional characteristics such as high protein content, which may help to alleviate these problems. The proximate composition (fat, moisture content, crude protein, ash, and carbohydrate) and antinutrient (tannin and phytate) level of winged bean seeds and tubers were determined using 50 accessions. In the processed seeds, accession Tpt17 had the highest protein content (40.30%) and Tpt48 the lowest (34.18%). In the unprocessed seeds, Tpt17 also recorded the highest crude protein (31.13%) with Tpt125 having the lowest (28.43%). In the tubers, protein content ranged from 19.07% (Tpt42) to 12.26% (Tpt10). The moisture content in the processed seeds ranged from 8.51% (Tpt42) to 6.72% (Tpt6); in the unprocessed seeds, it was between 8.53% (Tpt53) and 3.76% (Tpt14). In the processed seeds, the values of ash ranged from 4.93% (Tpt126) to 4.45% (Tpt15-4); in the unprocessed seeds, it ranged from 4.98% (Tpt17) to 4.55% (Tpt125). In the processed seeds, the fat content ranged from 18.91% (Tpt51) to 14.09% (Tp43) while in the unprocessed seeds, the values ranged from 19.01% (Tpt15) to 13.87% (Tpt3-B). The crude fiber in the processed samples ranged from 13.82% (Tpt6) to 10.40% (Tpt125) while in the unprocessed seeds, it ranged from 7.29% in Tpt51 to 4.83% in Tpt11. Carbohydrate content in the processed seeds ranged from 26.30% (Tpt3-B) to 20.94% (Tpt125) and 39.76% in Tpt3-B to 34.53% in Tpt18 in the unprocessed seeds. The tannin and phytate contents showed remarkably significant differences. In the tubers harvested, significant variation was observed in the parameters evaluated. Winged bean flour could be formulated into various meals for children and adults to reduce malnutrition in sub-Saharan Africa.

Chia Seed (Salvia hispanica L.) Pepsin Hydrolysates Inhibit Angiotensin-Converting Enzyme by Interacting with its Catalytic Site

High blood pressure can lead to cardiovascular diseases. The objective of this work was to obtain protein hydrolysates with antihypertensive potential from chia oil industry meal byproduct. Chia seed protein isolates (CPIs) were obtained from chia seed meal byproduct. CPI was hydrolyzed using different proteases (alcalase, pepsin, trypsin, and α-chymotrypsin) and their biological potential was evaluated using in vitro and in silico approaches. Chia seed pepsin protein hydrolysate showed the highest angiotensin-converting enzyme inhibition potential IC₅₀ of 0.128 mg/mL (P < 0.05) compared to the rest of hydrolysates. Peptide sequence LIVSPLAGRL presented the lowest predicted binding energy and highest inhibition potential (-9.5 kcal/mol) compared to other sequenced peptides and positive controls (captopril and lisinopril). Chia peptides showed potential to block angiotensin-converting enzyme by interacting with its catalytic site. Chia seed oil industry meal byproduct could be used as an inexpensive source of protein and bioactive peptides with antihypertensive potential. PRACTICAL APPLICATION: This research shows an upcycling alternative for chia oil industry byproduct. Chia meal is a rich source of protein and can be used to generate bioactive peptides with antihypertensive potential. Chia protein isolate was obtained from chia meal and hydrolyzed using different enzymes, pepsin showed the highest antihypertensive potential. Chia meal waste could be a low-cost source of protein and protein hydrolysates that could be used as a food ingredient with antihypertensive potential.

Peptides derived from lupin proteins confer potent protection against oxidative stress

BACKGROUND

Lupin seeds are rich in proteins, which are utilized in the food industry. There is an increased interest in lupin research due to its association with health-related benefits, such as reduction of hypertension and hyperglycemia. However, studies on the peptides derived from lupin proteins are rare.

RESULTS

Lupin protein hydrolysates (LPHs) were prepared by proteolysis using alcalase, trypsin and pepsin, respectively. All the hydrolysates demonstrated higher antioxidant and angiotensin I-converting enzyme (ACE) inhibitory activities compared to lupin proteins. The hydrolysates were fractionated into three fractions based on molecular weight (MW), and the peptides with MW < 3 kDa (LPH3) had the highest antioxidant and ACE inhibitory activities compared to other fractions. Cell model study revealed that LPH3 fraction had the highest protection against the generation of reactive oxygen species in HepG2 cells, which was associated with increased activities of superoxide dismutase and glutathione peroxidase through upregulation of SOD1, GPX1, GCLM, SLC7A11 and SRXN1 expression.

CONCLUSIONS

The analysis of amino acid composition indicated that the peptides were characterized with high content of hydrophobic amino acids, which may be responsible for the greatest antioxidant activity. This study highlights the promising potential of lupin peptides as a functional ingredient in healthy foods. © 2018 Society of Chemical Industry.

High angiotensin-I converting enzyme (ACE) inhibitory activity of Alcalase-digested green soybean (Glycine max) hydrolysates

As a protein-rich, underutilized crop, green soybean could be exploited to produce hydrolysates containing angiotensin-I converting enzyme (ACE) inhibitory peptides. Defatted green soybean was hydrolyzed using four different food-grade proteases (Alcalase, Papain, Flavourzyme and Bromelain) and their ACE inhibitory activities were evaluated. The Alcalase-generated green soybean hydrolysate showed the highest ACE inhibitory activity (IC50: 0.14 mg/mL at 6 h hydrolysis time) followed by Papain (IC50: 0.20 mg/mL at 5 h hydrolysis time), Bromelain (IC50: 0.36 mg/mL at 6 h hydrolysis time) and Flavourzyme (IC50: 1.14 mg/mL at 6 h hydrolysis time) hydrolysates. The Alcalase-generated hydrolysate was profiled based on its hydrophobicity and isoelectric point using reversed phase high performance liquid chromatography (RP-HPLC) and isoelectric point focusing (IEF) fractionators. The Alcalase-generated green soybean hydrolysate comprising of peptides EAQRLLF, PSLRSYLAE, PDRSIHGRQLAE, FITAFR and RGQVLS, revealed the highest ACE inhibitory activity of 94.19%, 99.31%, 92.92%, 101.51% and 90.40%, respectively, while their IC50 values were 878 μM, 532 μM, 1552 μM, 1342 μM and 993 μM, respectively. It can be concluded that Alcalase-digested green soybean hydrolysates could be exploited as a source of peptides to be incorporated into functional foods with antihypertensive activity.

Camel milk protein hydrolysates with improved technofunctional properties and enhanced antioxidant potential in in vitro and in food model systems

Camel milk protein hydrolysates (CMPH) were generated using proteolytic enzymes, such as alcalase, bromelain, and papain, to explore the effect on the technofunctional properties and antioxidant potential under in vitro and in real food model systems. Characterization of the CMPH via degree of hydrolysis, sodium dodecyl sulfate-PAGE, and HPLC revealed that different proteins in camel milk underwent degradation at different degrees after enzymatic hydrolysis using 3 different enzymes for 2, 4, and 6 h, with papain displaying the highest degradation. Technofunctional properties, such as emulsifying activity index, surface hydrophobicity, and protein solubility, were higher in CMPH than unhydrolyzed camel milk proteins. However, the water and fat absorption capacity were lower in CMPH compared with unhydrolyzed camel milk proteins. Antioxidant properties as assessed by 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities and metal-chelating activity were enhanced after hydrolysis, in contrast to ferric-reducing antioxidant power which showed a decrease after hydrolysis. The CMPH were also tested in real food model systems for their potential to inhibit lipid peroxidation in fish mince and grape seed oil-in-water emulsion, and we found that papain-produced hydrolysate displayed higher inhibition than alcalase- and bromelain-produced hydrolysates. Therefore, the CMPH demonstrated effective antioxidant potential in vitro as well as in real food systems and showed enhanced functional properties, which guarantees their potential applications in functional foods. The present study is one of few reports available on CMPH being explored in vitro as well as in real food model systems.

A Review on Current Status and Future Prospects of Winged Bean (Psophocarpus tetragonolobus) in Tropical Agriculture

Winged bean, Psophocarpus tetragonolobus (L.) DC., is analogous to soybean in yield and nutritional quality, proving a valuable alternative to soybean in tropical regions of the world. The presence of anti-nutritional factors and high costs associated with indeterminate plant habit have been major concerns in this crop. But occurrence of good genetic variability in germplasm collections offers precious resources for winged bean breeding. However, lack of germplasm characterization is hindering such efforts. From a genomic standpoint, winged bean has been little studied despite rapid advancement in legume genomics in the last decade. Exploiting modern genomics/breeding approaches for genetic resource characterization and the breeding of early maturing, high yielding, determinate varieties which are disease resistant and free of anti-nutritional factors along with developing consumer friendly value-added products of local significance are great challenges and opportunities in the future that would boost cultivation of winged bean in the tropics. We review past efforts and future prospects towards winged bean improvement.

Angiotensin-I-Converting Enzyme (ACE)-Inhibitory Peptides from Plants

Hypertension is an important factor in cardiovascular diseases. Angiotensin-I-converting enzyme (ACE) inhibitors like synthetic drugs are widely used to control hypertension. ACE-inhibitory peptides from food origins could be a good alternative to synthetic drugs. A number of plant-based peptides have been investigated for their potential ACE inhibitor activities by using in vitro and in vivo assays. These plant-based peptides can be obtained by solvent extraction, enzymatic hydrolysis with or without novel food processing methods, and fermentation. ACE-inhibitory activities of peptides can be affected by their structural characteristics such as chain length, composition and sequence. ACE-inhibitory peptides should have gastrointestinal stability and reach the cardiovascular system to show their bioactivity. This paper reviews the current literature on plant-derived ACE-inhibitory peptides including their sources, production and structure, as well as their activity by in vitro and in vivo studies and their bioavailability.

Preparation and characterisation of nanoliposomes containing winged bean seeds bioactive peptides

The aim of this study was to produce and characterise nanosize liposomes containing bioactive peptides with antioxidative and ACE-inhibitory properties, derived from winged bean seeds (WBS) protein. WBS powder was papain-proteolysed, at 70 °C and pH 6.5 for six hours, followed by encapsulation via a solvent-free heating method. The results showed that the WBS proteolysate was successfully incorporated into spherical, unilamellar liposomal particles, with particle diameter, polydispersity index, zeta potential and encapsulation efficiency of 193.3 ± 0.12 nm, 0.4 ± 0.02 (unit less), -70.5 ± 0.30 mV and 27.6 ± 1.17%, respectively. It also demonstrated good storage stability over eight weeks at 4 °C, indicated by slight increment (15.1%) in particle size and a zeta potential only weaker by 17.2% at the end of the study period. These results suggested the feasibility of entrapping water soluble peptides in hydrophobic liposomal system that, upon optimisation, has the potential to act as bioactive food ingredient.

ACE Inhibitory and Antioxidant Activities of Collagen Hydrolysates from the Ribbon Jellyfish (Chrysaora sp.)

Collagen isolated from the ribbon jellyfish (Chrysaora sp.) was hydrolysed using three different proteases (i.e. trypsin, alcalase and Protamex) to obtain bioactive peptides. Angiotensin-I-converting enzyme (ACE) inhibitory activity and antioxidant activities (i.e. ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity) of the peptides were measured and compared, and the effect of the duration of hydrolysis on the bioactivity (ACE inhibitory and antioxidant activities) of peptides was also evaluated. FRAP activity was the highest in Protamex-induced (25-27 mM) and trypsin-induced hydrolysates (24-26 mM) at 7 and 9 h, respectively. Conversely, hydrolysates produced by trypsin for 1 and 3 h showed the highest DPPH radical scavenging activities (94 and 92%, respectively). Trypsin-induced hydrolysates (at 3 h) also showed the highest ACE inhibitory activity (89%). The peptide sequences with the highest activities were identified using tandem mass spectrometry, and the results show that the hydrolysates had a high content of hydrophobic amino acids as well as unique amino acid sequences, which likely contribute to their biological activities.