Characterization and ACE-Inhibitory Activity of Amaranth Proteins

Exploration of the Nutritional and Functional Properties of Underutilized Grains as an Alternative Source for the Research of Food-Derived Bioactive Peptides

The estimated increase in world population will lead to a deterioration in global food security, aggravated in developing countries by hidden hunger resulting from protein deficiency. To reduce or avoid this crisis, a dietary shift towards the consumption of sustainable, nutrient-rich, and calorically efficient food products has been recommended by the FAO and WHO. Plant proteins derived from grains and seeds provide nutritionally balanced diets, improve health status, reduce poverty, enhance food security, and contain several functional compounds. In this review, the current evidence on the nutritional and functional properties of underutilized grains is summarized, focusing on their incorporation into functional foods and the role of their proteins as novel source of bioactive peptides with health benefits.

Comparison of the Effect of Amaranth Oil vs. Rapeseed Oil on Selected Atherosclerosis Markers in Overweight and Obese Subjects: A Randomized Double-Blind Cross-Over Trial

It is well known that rapeseed oil improves lipid profile and has antiatherosclerotic properties. Recently, amaranth oil has also become popular due to its potential health benefits. However, the effect of this oil on atherosclerosis markers in humans is not clear. Therefore, this study aimed to compare the effect of amaranth and rapeseed oils on selected atherosclerosis-related parameters in overweight and obese subjects. In this randomized cross-over study, 44 subjects were instructed to consume 20 mL of amaranth oil and rapeseed oil during two consecutive three-week intervention periods separated by a washout period of the same duration as the intervention. The outcome variables included changes in tumor necrosis factor-alpha, adiponectin, oxidized low-density lipoprotein, apolipoproteins (Apo) A1, B and E as well as glucose and insulin homeostasis markers. Compared to rapeseed oil, amaranth oil had a slight positive effect on adiponectin levels (mean (95% confidence interval): 0.55 (0.22-0.89) vs. -0.29 (-0.75-0.16), p = 0.0002) but negatively affected ApoB concentrations (0.05 (-0.01-0.11) vs. 0.03 (-0.07-0.00), p = 0.0004) and ApoB/A1 ratio (0.01 (-0.03-0.05) vs. -0.02 (-0.04-0.00), p = 0.0113). No differences between the other analyzed parameters were observed. In conclusion, amaranth oil does not have a greater beneficial effect on atherosclerosis markers than rapeseed oil. However, further studies with a longer intervention period are needed. The study was retrospectively registered with the German Clinical Trials Register within the number: DRKS00014046, date of registration: 3 May 2018.

Amaranth as a Source of Antihypertensive Peptides

Amaranth is an ancestral crop used by pre-Columbian cultures for 6000 to 8000 years. Its grains have a relevant chemical composition not only from a nutritional point of view but also due to the contribution of components with good techno-functional properties and important potential as bioactive compounds. Numerous studies have shown that amaranth storage proteins possess encrypted sequences that, once released, exhibit different physiological activities. One of the most studied is antihypertensive activity. This review summarizes the progress made over the last years (2008-2020) related to this topic. Studies related to inhibition of different enzymes of the Renin-Angiotensin-Aldosterone system, in particular Angiotensin Converting Enzyme (ACE) and Renin, as well as those referring to potential modulation mechanisms of tissue or local Renin-Angiotensin-Aldosterone system, are analyzed, including in silico, in vitro, in vivo, and ex vivo assays. Furthermore, the potential use of these bioactive peptides or products containing them, in the elaboration of functional food matrices is discussed. Finally, the most relevant conclusions and future requirements in research and development of food products are presented.

Pseudocereal grains: Nutritional value, health benefits and current applications for the development of gluten-free foods

Nowadays, consumers are more conscious of the environmental and nutritional benefits of foods. Pseudocereals grains, edible seeds belonging to dicotyledonous plant species, are becoming a current trend in human diets as gluten-free (GF) grains with excellent nutritional and nutraceutical value. Pseudocereals are a good source of starch, fiber, proteins, minerals, vitamins, and phytochemicals such as saponins, polyphenols, phytosterols, phytosteroids, and betalains with potential health benefits. The present review aims to summarize the nutritional quality and phytochemical profile of the three main pseudocereal grains: quinoa, amaranth and buckwheat. In addition, current evidence about their health benefits in animal models and human studies is also provided in detail. Based on the accumulating research supporting the inclusion of pseudocereals grains in the diet of celiac persons, this review discusses the recent advances in their application for the development of new GF products. Future directions for a wider cultivation and commercial exploitation of these crops are also highlighted.

Amaranth as a potential dietary adjunct of lifestyle modification to improve cardiovascular risk profile

The aim of this review was to summarize data regarding amaranth as a potential component of lifestyle modification to improve cardiovascular risk profiles by modifying cardiovascular risk factors such as cholesterol, diabetes, and hypertension. PubMed was searched for appropriate articles. The main inclusion criteria for articles were as follows: interventions with amaranth; conducted in humans or animals or in vitro; and reported serum lipids and lipoprotein levels, and antidiabetic, antihypertensive, and antioxidant abilities. The outcome measures were changes in serum lipids and the presence of antidiabetic, antihypertensive, and antioxidant activity. A total of 33 articles were included herein. Regarding hypolipidemic activity, most studies investigated the effect of intervention with amaranth in animals, and fewer studies were performed in humans. Most studies in animal models demonstrated the ability of amaranth to decrease total cholesterol and low-density lipoprotein cholesterol. Pilot studies in humans were not convincing regarding amaranth's lipid-lowering activity. Based on this search, it is not clear which constituents are potentially responsible for the hypocholesterolemic effect of amaranth. Some authors tend to think that squalene can play a role in this effect, whereas others suggest that different components of amaranth are of greater importance (eg, sterols, oil fractions rich in fatty acids, proteins, amino acids, or fiber) for its hypocholesterolemic effect. It is possible that several constituents are jointly responsible for this action. Regarding the antidiabetic, antihypertensive, and antioxidant activities, most studies were performed in vitro and showed good potential for all three biological effects. Future research should focus on clarifying the effect of amaranth on high-density lipoprotein cholesterol, identifying the constituents responsible for these beneficial effects, and providing more data regarding its use in humans, ideally using randomized controlled trials. The antidiabetic, antihypertensive, and antioxidant activities found in vitro should be confirmed further in animal or human models.

PepSAVI-MS Reveals a Proline-rich Antimicrobial Peptide in Amaranthus tricolor

Traditional medicinal plants are a rich source of antimicrobials; however, the bioactive peptide constituents of most ethnobotanical species remain largely unexplored. Herein, PepSAVI-MS, a mass spectrometry-based peptidomics pipeline, was implemented for antimicrobial peptide (AMP) discovery in the medicinal plant Amaranthus tricolor. This investigation revealed a novel 1.7 kDa AMP with strong activity against Escherichia coli ATCC 25922, deemed Atr-AMP1. Initial efforts to determine the sequence of Atr-AMP1 utilized chemical derivatization and enzymatic digestion to provide information about specific residues and post-translational modifications. EThcD (electron-transfer/higher-energy collision dissociation) produced extensive backbone fragmentation and facilitated de novo sequencing, the results of which were consistent with orthogonal characterization experiments. Additionally, multistage HCD (higher-energy collisional dissociation) facilitated discrimination between isobaric leucine and isoleucine. These results revealed a positively charged proline-rich peptide present in a heterogeneous population of multiple peptidoforms, possessing several post-translational modifications including a disulfide bond, methionine oxidation, and proline hydroxylation. Additional bioactivity screening of a simplified fraction containing Atr-AMP1 revealed activity against Staphylococcus aureus LAC, demonstrating activity against both a Gram-negative and a Gram-positive bacterial species unlike many known short chain proline-rich antimicrobial peptides.

Effect of amaranth proteins on the RAS system. In vitro, in vivo and ex vivo assays

The aim of this work was to analyse the hypotensive effect of amaranth protein/peptides on spontaneously hypertensive rats (SHR). The mechanism of action of these peptides was studied in vivo and ex vivo. We also tested the effect of protection against gastrointestinal digestion (GID) exerted by an O:W emulsion on the integrity of the antihypertensive peptides. All samples tested produced a decrease in blood pressure (SBP). The animals treated with emulsion (G_E) and emulsion + peptide (G_E+VIKP) showed the most significant reduction in the SBP (42 ± 2 mmHg and 35 ± 2 mmHg, respectively). The results presented suggest that after GID, a variety of peptides with biological activities were released or were resistant to this process. These peptides play a role in the regulation of the SBP by acting on plasma ACE, plasma renin and the vascular system. These results support the use of amaranth protein/peptides in the elaboration of functional foods for hypertensive individuals.

Sequence Identification of Bioactive Peptides from Amaranth Seed Proteins (Amaranthus hypochondriacus spp.)

Amaranthus hypochondriacus spp. is a commonly grown cereal in Latin America, known for its high protein content. The objective of this study was to separate and identify bioactive peptides found in amaranth seeds through enzymatically-assisted hydrolysis using alcalase and flavourzyme. Hydrolysis was carried out for each enzyme separately and compared to two-step continuous process where both enzymes were combined. The biological activity of the resulting three hydrolysates was analyzed, finding, in general, higher bioactive potential of the hydrolysate obtained in a continuous process (combined enzymes). Its fractions were separated by RP-HPLC, and their bioactivity was analyzed. In particular, two fractions showed the highest biological activity as ACE inhibitors with IC50 at 0.158 and 0.134, thrombin inhibitors with IC50 of 167 and 155, and antioxidants in ABTS assay with SC50 at 1.375 and 0.992 mg/L, respectively. Further sequence analysis of the bioactive peptides was carried out using MALDI-TOF, which identified amino acid chains that have not been reported as bioactive so far. Bibliographic survey allowed identification of similarities between peptides reported in amaranth and other proteins. In conclusion, amaranth proteins are a potential source of peptides with multifunctional activity.

Pasta Enrichment with an Amaranth Hydrolysate Affects the Overall Acceptability while Maintaining Antihypertensive Properties

BACKGROUND

Alcalase-treated amaranth proteins generate angiotensin-1-converting enzyme (ACE-1) inhibitory peptides, which could be useful for functional foods development. Our aim was to evaluate the technological, sensory, and antihypertensive properties of pasta enriched with an amaranth hydrolysate.

METHODS

Pasta with 11% (A; control), 15% (B), and 20% (C) of protein content were formulated. Pastas B and C were supplemented with an alcalase-treated amaranth protein concentrate. Cooking time, cooking lost, color, and texture were assessed. An untrained panel (n = 30) evaluated sensory attributes. The antihypertensive effect was evaluated in hypertensive rats.

RESULTS

The hydrolysate IC50 was 0.014 mg/mL. Optimum cooking time and cooking loss decreased in products B and C vs. A (p < 0.05). The L* values decreased in pasta C. Firmness increased in pasta C vs. A (p < 0.05). Adhesiveness was different among groups (p < 0.05). Pasta A had the highest acceptability (p < 0.05). The products B and C, and captopril (positive control) showed antihypertensive properties after 3 h of supplementation (p < 0.05). This effect remained after 7 h, 8 h, or 9 h.

CONCLUSIONS

The addition of amaranth hydrolysates to pasta negatively impacts on the overall acceptability and, to a lesser extent, on pasta taste. However, it is possible to maintain the antihypertensive properties of the supplemented pasta under physiological conditions.

Release of multifunctional peptides from kiwicha (Amaranthus caudatus) protein under in vitro gastrointestinal digestion

BACKGROUND

The multifactorial origin of many chronic diseases provides a new framework for the development of multifunctional foods. In this study, the effect of in vitro simulated gastrointestinal digestion of kiwicha (Amaranthus caudatus) proteins on the release of multifunctional peptides was evaluated.

RESULTS

Gastric digest showed higher angiotensin I converting enzyme (ACE) inhibitory activity while 60 min gastroduodenal digest showed the highest antioxidant, dipeptidyl peptidase IV (DPP-IV), α-amylase and Caco-2 cell viability inhibitory activities. Peptides >5 kDa were more effective in inhibiting colon cancer cell viability, whereas peptides <5 kDa were mainly responsible for the antioxidant, ACE, DPP-IV and α-amylase inhibitory activities. Thirteen peptides from amaranth sequenced proteins were identified. Structure-activity relationship analysis of the identified sequences pointed to three amaranth fragments, namely FLISCLL, SVFDEELS and DFIILE, as potential peptides able to concurrently exert antioxidant capacity and ability to inhibit both ACE and α-amylase.

CONCLUSIONS

Five of thirteen peptides identified in kiwicha protein digests show high potential to exert multifunctional properties. Thus kiwicha proteins might start to gain importance as ingredients for functional foods for the prevention and/or management of chronic diseases related to oxidative stress, hypertension and/or diabetes. © 2018 Society of Chemical Industry.

Functional properties of amaranth, quinoa and chia proteins and the biological activities of their hydrolyzates

Amaranth, quinoa and chia are non-conventional sources of proteins whose interest has increased in recent years due to their excellent nutritional value. Vegetable proteins can be used as food ingredients to replace animal proteins in human diet. The present article provides a comprehensive analysis of amaranth, quinoa and chia proteins and focuses on their solubility, superficial, gelling and textural properties as well as on the biological activities of enzymatic hydrolyzates.

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.

Amaranth Protein Hydrolysates Efficiently Reduce Systolic Blood Pressure in Spontaneously Hypertensive Rats

Alcalase is the enzyme of choice to release antihypertensive peptides from amaranth proteins, but the hydrolysis conditions have not been optimized yet. Furthermore, in vivo assays are needed to confirm such a hypotensive effect. Our aim was to optimize the hydrolysis of amaranth protein with alcalase and to test in vivo the hypotensive effect of the hydrolysates. A response surface analysis was carried out to optimize the hydrolysis reaction. The response variable was the Angiotensin Converting Enzyme (ACE-I) inhibition. The hydrolysis degree was determined (free alpha-amino groups measurement). The optimized hydrolysate bioavailability was assessed in the sera of mice and the hypotensive effect was assessed in spontaneously hypertensive rats. Control groups were administered captopril or water. The optimized hydrolysis conditions were: pH = 7.01, temperature = 52 °C, enzyme concentration 0.04 mU/mg, and time = 6.16 h. The optimized hydrolysate showed a 93.5% of ACE-I inhibition and a hydrolysis degree of 74.77%. After supplementation, the hydrolysate was bioavailable in mice from 5 to 60 min, and the hypotensive effect started at 4 h in spontaneously hypertensive rats (p < 0.05 vs. water group). This effect was similar to the captopril hypotensive effect for the next 3 h (p > 0.05). The use of amaranth-optimized hydrolysates as hypotensive supplements or ingredient for functional foods seems feasible.

Recent Research in Antihypertensive Activity of Food Protein-derived Hydrolyzates and Peptides

Year to year obesity prevalence, reduced physical activities, bad habits/or stressful lifestyle, and other environmental and physiological impacts lead to increase in diseases such as coronary heart disease, stroke, cancer, diabetes, and hypertension worldwide. Hypertension is considered as one of the most common serious chronic diseases; however, discovery of medications with high efficacy and without side effects for treatment of patients remains a challenge for scientists. Recent trends in functional foods have evidenced that food bioactive proteins play a major role in the concepts of illness and curing; therefore, nutritionists, biomedical scientists, and food scientists are working together to develop improved systems for the discovery of peptides with increased potency and therapeutic benefits. This review presents a recent research carried out to date for the purpose of isolation and identification of bioactive hydrolyzates and peptides with angiotensin I converting enzyme inhibitory activity and antihypertensive effect from animal, marine, microbial, and plant food proteins. Effects of food processing and hydrolyzation conditions as well as some other impacts on formation, activity, and stability of these hydrolyzates and peptides are also presented.

Supplementation with fruit and okara soybean by-products and amaranth flour increases the folate production by starter and probiotic cultures

The ability of two starter cultures (Streptococcus (S.) thermophilus ST-M6 and St. thermophilus TA-40) and eleven probiotic cultures (St. thermophilus TH-4, Lactobacillus (Lb.) acidophilus LA-5, Lb. fermentum PCC, Lb. reuteri RC-14, Lb. paracasei subsp. paracasei, Lb. casei 431, Lb. paracasei subsp. paracasei F19, Lb. rhamnosus GR-1, and Lb. rhamnosus LGG, Bifidobacterium (B.) animalis subsp. lactis BB-12, B. longum subsp. longum BB-46, and B. longum subsp. infantis BB-02) to produce folate in a modified MRS broth (mMRS) supplemented with different fruit (passion fruit, acerola, orange, and mango) and okara soybean by-products and amaranth flour was investigated. Initially, the folate content of each vegetable substrate was determined: passion fruit by-product showed the lowest folate content (8±2ng/mL) and okara the highest (457±22ng/mL). When the orange by-product and amaranth flour were added to mMRS, all strains were able to increase folate production after 24h of fermentation. B. longum subsp infantis BB-02 produced the highest concentrations (1223±116ng/mL) in amaranth flour. Okara was the substrate that had the lowest impact on the folate production by all strains evaluated. Lb. acidophilus LA-5 (297±36ng/mL) and B. animalis subsp. lactis BB-12 (237±23ng/mL) were also able to produce folate after growth in mMRS containing acerola and orange by-products, respectively. The results of this study demonstrate that folate production is not only strain-dependent but also influenced by the addition of different substrates in the growth media.

Preparation of nanoliposome loaded with peanut peptide fraction: stability and bioavailability

Nanoliposome loaded with peanut peptide fraction (PPF) prepared by high pressure microfluidization (HPM) treatment was investigated as well as its stability and bioavailability.

Intake of heat-expanded amaranth grain reverses endothelial dysfunction in hypercholesterolemic rabbits

Feeding amaranth grain to hypercholesterolemic rabbits showed the property of recovering the lost endothelial function even without removing the hypercholesterolemia-inducing diet. Results suggest an underlying protective effect.

Angiotensin I-Converting Enzyme inhibitory and antioxidant activities and surfactant properties of protein hydrolysates as obtained of Amaranthus hypochondriacus L. grain

Even though some research has been carried out on surfactant properties of amaranth protein hydrolysates, their bio-functionality has not been studied yet. In this work amaranth grain Alb 1 and Glob were hydrolyzed (Alb 1H, Glob H) and foams and emulsions at optimal conditions (t, E/S, pH5) were prepared in order to assess techno-functional properties such as foaming (F) and emulsifying (E) (capacity (C) and stability (S)). FC and EC were much better for Glob H than for Alb H. Angiotensin I-converting enzyme-inhibitory activity was higher for Alb 1H (roughly 50 %) than that of Glob H (roughly 30 %). Scavenging of radicals activity (DPPH· or ABTS· (+) ) of Alb 1H and Glob H, at 2 mg/mL, was similar (approx. 40 %), but lower than Alb 1 (approx. 70 %), which was the best antioxidant. The low reducing power showed that hydrolysates barely donate an electron or hydrogen. Chelating activity on Cu(2+) was lower than that exhibited by Fe(2+,) which was remarkable, approx. 80 % as long as DH% > 10 %, where hydrolysates displayed high solubility (Alb 1H = 85 %, Glob H = 70 %) because of occurrence of 1-10 kDa peptides. Amaranth foams and emulsions prepared with protein hydrolysates have a potential as a nutraceutical food.

State of knowledge on amaranth grain: a comprehensive review

Amaranth grain is a highly nutritional pseudocereal with a superior amount of proteins when compared to true cereals. It is a reasonably well-balanced food with functional properties that have been shown to provide medicinal benefits. The health benefits attributed include decreasing plasma cholesterol levels, stimulating the immune system, exerting an antitumor activity, reducing blood glucose levels and improving conditions of hypertension and anemia. In addition, it has been reported to possess anti-allergic and antioxidant activities. The present article provides a comprehensive overview of amaranth grain that focuses on recent research reporting its use in the clinical practice and its possible benefits to human health.

Angiotensin-converting enzyme inhibitory and antioxidative activities and functional characterization of protein hydrolysates of hard-to-cook chickpeas

BACKGROUND

The potential use of hard-to-cook (hardened) chickpeas to obtain value-added functional food ingredients was evaluated. For that purpose, some nutraceutical and functional attributes of several chickpea protein hydrolysates (CPHs) prepared from both fresh and hard-to-cook grains were evaluated.

RESULTS

All the CPHs prepared from both fresh and hard-to-cook grains, with the enzymes alcalase, pancreatin and papain, showed high angiotensin converting enzyme inhibitory (ACE-I) activity with IC₅₀ values ranging from 0.101 to 37.33 µg mL⁻¹; similarly, high levels of antioxidant activity (around 18.17-95.61 µmol Trolox equivalent antioxidant capacity µg⁻¹ CPH) were obtained through both the 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) methods. Regarding functional characterization of the CPHs, oil absorption values ranged from 1.91 to 2.20 mL oil g⁻¹ CPH, with water solubility almost 100% from pH 7 to 10.

CONCLUSION

The high antioxidant and ACE-I activities as well as the good functional properties of the CPH prepared from both fresh and hard-to-cook grains, suggest its use in food formulations with value added in human health.

Chemical composition and bile acid binding activity of products obtained from amaranth (Amaranthus cruentus) seeds

Cardiovascular diseases are currently the greatest cause of mortality in the world, and dislipidemia is appearing as one of the most important risk factors. The binding of bile acids (BAs) has been hypothesized as a possible mechanism by which dietary fibers lower blood cholesterol levels. Besides the fibers, other components in the amaranth seeds may be related to this hypocholesterolemic effect. The objective of the present study was to evaluate the BA binding capacity of some products obtained from defatted amaranth flour (DAF) and from the amaranth protein concentrate (APC). The alkaline residue, rich in fibers (8.6%), presented the lowest binding activity for the BAs tested, with the exception of glycocholic acid. The DAF showed intermediary binding activity for all the BAs tested, although similar to that of the APC for deoxycholic acid, and to that of the amaranth protein hydrolysate (APH) for taurocholic acid. The DAF and APC showed binding activity for secondary bile acids toxic to the intestinal mucus. From the results, amaranth products were shown to have the ability to bind BAs, but it was not possible to affirm whether the main component responsible for this activity was the proteins, fibers or eventually some other non-evaluated component.

Amaranth lunasin-like peptide internalizes into the cell nucleus and inhibits chemical carcinogen-induced transformation of NIH-3T3 cells

Because an unbalanced diet is an important risk factor for several illnesses, interest has increased in finding novel health-promoting foods. Amaranth produces seeds that not only have substantial nutritional properties but that also contain phytochemical compounds as rutin and nicotiflorin and peptides with antihypertensive and anticarcinogenic activities. We report that a cancer-preventive peptide in amaranth has activities similar to those of soybean lunasin. The amaranth lunasin-like peptide, however, requires less time than the soybean lunasin to internalize into the nucleus of NIH-3T3 cells, and inhibits histone acetylation (H(3) and H(4) in a 70 and 77%, respectively). The amaranth lunasin-like peptide inhibited the transformation of NIH-3T3 cells to cancerous foci. The open reading frame (ORF) of amaranth lunasin corresponds to a bifunctional inhibitor/lipid-transfer protein (LTP). LTPs are a family of proteins that in plants are implicated in different functions, albeit all linked to developmental processes and biotic and abiotic stress resistance. Our results open new intriguing questions about the function of lunasin in plants and support that amaranth is a food alternative containing natural peptides with health-promoting benefits.