Soybean peptide lunasin suppresses in vitro and in vivo 7,12-dimethylbenz[a]anthracene-induced tumorigenesis

"Top-down" overexpression optimization of butelase-1 in Escherichia coli and its application in anti-tumor peptides

Butelase-1, the fastest known Asn/Asp-specific peptide ligase capable of catalyzing peptide ligation and cyclization, holds promising application prospects in the fields of food and biology. However, limited research exists on its recombinant expression and potential applications in peptide drugs. In this study, the activity of recombinantly-produced butelase-1 was enhanced by co-expressing it with a molecular chaperone in the SHuffle T7 strain. By introducing single or multiple synonymous rare codons at the beginning of the coding regions of beta-strand or alpha-helix, in combination with ribosomal binding site engineering, the activity of butelase-1 could be further improved. Consequently, the butelase-1 with a specific activity of 386.93 U/mg and a catalytic efficiency of 11,048 M-1 s-1 was successfully prepared in E. coli, resulting in a total activity of 8183.54 U/L and a yield of about 100 mg/L. This optimized butelase-1 was then used to efficiently cyclize the redesigned anti-cancer peptide lunasin, leading to enhanced bioavailability and anti-cancer effects. Overall, this study not only provided valuable biotechnology strategies for improving the recombinant expression of butelase-1 but also demonstrated a successful application for enhancing the biological efficacy of anti-cancer peptides.

Steady-State Delivery and Chemical Modification of Food Nutrients to Improve Cancer Intervention Ability

Cancer is a crucial global health problem, and prevention is an important strategy to reduce the burden of the disease. Daily diet is the key modifiable risk factor for cancer, and an increasing body of evidence suggests that specific nutrients in foods may have a preventive effect against cancer. This review summarizes the current evidence on the role of nutrients from foods in cancer intervention. It discusses the potential mechanisms of action of various dietary components, including phytochemicals, vitamins, minerals, and fiber. The findings of epidemiological and clinical studies on their association with cancer risk are highlighted. The foods are rich in bioactive compounds such as carotenoids, flavonoids, and ω-3 fatty acids, which have been proven to have anticancer properties. The effects of steady-state delivery and chemical modification of these food's bioactive components on anticancer and intervention are summarized. Future research should focus on identifying the specific bioactive compounds in foods responsible for their intervention effects and exploring the potential synergistic effects of combining different nutrients in foods. Dietary interventions that incorporate multiple nutrients and whole foods may hold promise for reducing the risk of cancer and improving overall health.

Nano-liposomal zein hydrolysate for improved apoptotic activity and therapeutic index in lung cancer treatment

Lung cancer is one of the most common cancers in the world with a high mortality rate. Zein is a protein compound whose protein isolate is not useful and whose protein hydrolysis produces biological activity. By encapsulating this bioactive compound inside the nanoparticles (NPs), it causes itself to reach the tumor site and destroy it rapidly. In this study, the effects of zein hydrolysate (ZH) and nano-liposomal ZH (N-ZH) were investigated on the human A549 cell line. Western blotting and cell cycle analyses showed that ZH and N-ZH caused cytotoxicity. They induced apoptosis via cell cycle arrest at the G0 phase, as well as significant increases in pro-apoptotic genes, such as Bax, caspase-3, -8, -9, and p53, accompanied with significant decreases in the anti-apoptotic marker Bcl-2. Based on the results, the cytotoxic and anticancer effects of N-ZH were higher than those of free ZH. In conclusion, liposomes improved the performance of ZH and dramatically reduced the IC₅₀ value of ZH. These findings provided the experimental evidence that N-ZH with favorable anticancer activity can be used as a therapeutic agent and strategy for lung cancer treatment in future clinical trials.

Immunomodulatory peptides-A promising source for novel functional food production and drug discovery

Immunomodulatory peptides are a complex class of bioactive peptides that encompasses substances with different mechanisms of action. Immunomodulatory peptides could also be used in vaccines as adjuvants which would be extremely desirable, especially in response to pandemics. Thus, immunomodulatory peptides in food of plant origin could be regarded both as valuable suplements of novel functional food preparation and/or as precursors or possible active ingredients for drugs design for treatment variety of conditions arising from impaired function of immune system. Given variety of mechanisms, different tests are required to assess effects of immunomodulatory peptides. Some of those effects show good correlation with in vivo results but others, less so. Certain plant peptides, such as defensins, show both immunomodulatory and antimicrobial effect, which makes them interesting candidates for preparation of functional food and feed, as well as templates for design of synthetic peptides.

Production, Purification, and Potential Health Applications of Edible Seeds' Bioactive Peptides: A Concise Review

Edible seeds play a significant role in contributing essential nutritional needs and impart several health benefits to improve the quality of human life. Previous literature evidence has confirmed that edible seed proteins, their enzymatic hydrolysates, and bioactive peptides (BAPs) have proven and potential attributes to ameliorate numerous chronic disorders through the modulation of activities of several molecular markers. Edible seed-derived proteins and peptides have gained much interest from researchers worldwide as ingredients to formulate therapeutic functional foods and nutraceuticals. In this review, four main methods are discussed (enzymatic hydrolysis, gastrointestinal digestion, fermentation, and genetic engineering) that are used for the production of BAPs, including their purification and characterization. This article’s main aim is to provide current knowledge regarding several health-promoting properties of edible seed BAPs in terms of antihypertensive, anti-cancer, antioxidative, anti-inflammatory, and hypoglycemic activities.

The potential of lunasin extract for the prevention of breast cancer progression by upregulating E-Cadherin and inhibiting ICAM-1

Background: Research in natural substances for their anticancer potential has become increasingly popular. Lunasin, a soybean protein, is known to inhibit cancer progression via various pathways.  The aim of this study was to investigate the effect of Lunasin Extract (LE) on the expression of Intercellular Adhesion Molecule 1 (ICAM-1) and epithelial cadherins (E-Cadherin) in breast cancer. Methods: In this true-experimental in vivo study, 24 Sprague-Dawley rats that were induced by 7,12-Dimethylbenz[a]anthracene (DMBA), were used. Based on the therapy given, the groups were divided into, normal, positive control (PC), negative control (NC), adjuvant, curative, and preventive. Lunasin was extracted from soybean seeds of the Grobogan variety in Indonesia. Tissue samples were obtained, processed, stained with anti-ICAM-1 and anti-E-Cadherin antibodies, examined under a microscope, and quantified using H-score. The data were analyzed using ANOVA, which was then followed by Duncan's test.  Results: Statistically significant difference in ICAM-1 expression was observed between the following groups: adjuvant and NC, normal and NC, PC and NC, adjuvant and preventive, normal and preventive, PC and preventive, adjuvant and curative, normal and curative, PC and curative. E-Cadherin expression was significantly different between preventive and NC, adjuvant and NC, PC and NC, normal and NC, adjuvant and curative, PC and curative, normal and curative, normal and preventive. Significant negative correlation was found between ICAM-1 and E-Cadherin [-0.616 (-0.8165; -0.283)] with p = 0.001.  Conclusion: Preventive dose of LE was able to reduce ICAM-1 expression while increasing E-Cadherin expression.

Use of anticancer peptides as an alternative approach for targeted therapy in breast cancer: a review

Breast cancer is the most common cancer in women worldwide. Traditional therapies are expensive and cause severe side effects. Targeted therapy is a powerful method to circumvent the problems of other therapies. It also allows drugs to localize at predefined targets in a selective manner. Currently, there are several monoclonal antibodies which target breast cancer cell surface markers. However, using antibodies has some limitations. In the last two decades, many investigators have discovered peptides that may be useful to target breast cancer cells. In this article, we provide an overview on anti-breast cancer peptides, their sources and biological activities. We further discuss the pros and cons of using anticancer peptides with further emphasis on how to improve their effectiveness in cancer therapy.

Soy Intake and Colorectal Cancer Risk: Results from a Pooled Analysis of Prospective Cohort Studies Conducted in China and Japan

BACKGROUND

Soy is commonly consumed in east Asian countries and is suggested to reduce colorectal cancer (CRC) risk. However, results from epidemiologic studies are inconsistent, despite the anti-inflammatory and antiproliferative properties of soy isoflavones and soy protein.

OBJECTIVE

We evaluated the association between soy isoflavones and soy protein and CRC risk using 4 prospective cohort studies from China and Japan.

METHODS

Data were pooled from the Shanghai Women's Health Study (SWHS), Shanghai Men's Health Study (SMHS), Japan Public Health Center-based Prospective Study Cohort 1 (JPHC1), and Cohort 2 (JPHC2). Cox proportional hazards models estimated HRs and corresponding 95% CIs for the association of soy protein and isoflavone intake with CRC risk. The study included 205,060 individuals, among whom 2971 were diagnosed with incident CRC over an average follow-up of 12.7 y.

RESULTS

No statistically significant associations with CRC risk were observed for soy protein or isoflavone intake. No association was observed among ever smokers consuming higher isoflavones (HRisoflavones: 0.83; 95% CI: 0.68, 1.00) and soy protein (HRsoy protein: 0.81; 95% CI: 0.39, 1.10). However, risk reductions were observed among premenopausal women with a body mass index [BMI (kg/m2)] <23.0 at baseline for higher isoflavone (HRisoflavones: 0.58, 95% CI: 0.34, 0.98).

CONCLUSIONS

No evidence for an overall reduction in CRC risk by increasing soy food intake (i.e., protein or isoflavones) was observed. However, the association between soy and CRC risk may vary by BMI, smoking, and menopausal status among women. Future investigations are needed to further understand the biologic mechanisms observed.

Oral Administration of CardioAid and Lunasin Alleviates Liver Damage in a High-Fat Diet Nonalcoholic Steatohepatitis Model

BACKGROUND

Several of the drugs in development for treatment of nonalcoholic steatohepatitis (NASH) target liver fibrosis or have side effects that prohibit their long-term use in patients with mild to moderate disease. Lunasin is a soy-derived peptide with anti-inflammatory properties. ADM's CardioAid™ is a plant sterol extract that exerts cholesterol- and triacylglycerol-lowering effects.

AIM

To determine the immunomodulatory effects of CardioAid and lunasin in a high-fat diet (HFD) animal model of NASH.

METHODS

C57BL/6 mice on an HFD were orally administered CardioAid or lunasin for 25 weeks. The effects on the immune system, liver function, insulin resistance and lipid profile were studied.

RESULTS

Treatment with CardioAid and lunasin was associated with a significant decrease in the CD4/CD8 ratio and an increase in CD4+CD25+ lymphocytes. A decrease in interleukin 1-alpha serum levels and an increase in transforming growth factor beta serum levels were noted. These were associated with alleviation of liver damage as indicated by a significant decrease in liver enzymes and improvement in the histological nonalcoholic fatty liver disease activity score (NAS). Decreases in both serum triglyceride and serum glucose levels were observed in treated mice. A decrease in total body fat measured by EchoMRI was also observed in treated mice.

CONCLUSIONS

CardioAid and lunasin exerted hepatoprotective and glucose-protective effects in an HFD NASH model. These data and the high-safety profiles of CardioAid and Lunasin support their use in patients in the early stages of NASH to prevent deterioration due to the disease.

Updating the research on the chemopreventive and therapeutic role of the peptide lunasin

Chronic diseases have become the medical challenge of the 21st century because of their high incidence and mortality rates. Modulation of diet and lifestyle habits is considered as the best strategy for the prevention of these disorders. Health promoting benefits beyond their nutritional effects have been described for multiple dietary compounds. Among these compounds, the peptide lunasin is considered as one of the most promising. Naturally present in soybean, lunasin has been extensively studied in the last two decades because of its potential against chronic diseases such as cancer, cardiovascular and immunological disorders. The purpose of this article is to summarise the evidence on the presence of lunasin in soybean and derived foods, and its bioavailability once it is orally ingested. The protective and therapeutic effects of this peptide against cancer, oxidative stress, inflammation, and high cholesterol levels as well as the molecular mechanisms of action involved in these effects are also described in this review. © 2017 Society of Chemical Industry.

Antioxidant Activity of Zein Hydrolysates from Zea Species and Their Cytotoxic Effects in a Hepatic Cell Culture

In recent years, food proteins with bioactivity have been studied for cancer treatment. Zein peptides have shown an important set of bioactivities. This work compares the cytotoxic activity of zein hydrolyzed, extracted from four Zea species: teosinte, native, hybrid, and transgenic (Teo, Nat, Hyb, and HT) in a hepatic cell culture. Zein fraction was extracted, quantified, and hydrolyzed. Antioxidant capacity and cytotoxicity assays were performed on HepG2 cells. The levels of expression of caspase 3, 8, and 9 were evaluated in zein-treated cell cultures. Zea parviglumis showed the highest zein content (46.0 mg/g) and antioxidant activity (673.40 TE/g) out of all native zeins. Peptides from Hyb and HT showed high antioxidant activity compared to their native counterparts (1055.45 and 724.32 TE/g, respectively). Cytotoxic activity was observed in the cell culture using peptides of the four Zea species; Teo and Nat (IC50: 1781.63 and 1546.23 ng/mL) had no significant difference between them but showed more cytotoxic activity than Hyb and HT (IC50: 1252.25 and 1155.56 ng/mL). Increased expression of caspase 3 was observed in the peptide-treated HepG2 cells (at least two-fold more with respect to the control sample). These data indicate the potential for zein peptides to prevent or treat cancer, possibly by apoptosis induction.

Water dynamics of Ser-His-Glu-Cys-Asn powder and effects of moisture absorption on its chemical properties

BACKGROUND

This study has elucidated moisture dynamics in the soybean peptide, Ser-His-Glu-Cys-Asn (SHECN) powder by using dynamic vapor sorption (DVS) and nuclear magnetic resonance (NMR). We also tried to investigate the effects of moisture absorption on the biological activity and chemical properties of SHECN with some effective methods such as mid-infrared (MIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).

RESULTS

DVS results showed that the moisture absorption of SHECN could reach a maximum of 33%, and the SHECN powder after synthesis actually existed in a trihydrate state of SHECN.3H2 O. Low-field NMR revealed that three water proportions including strong combined water, binding water and bulk water were involved in SHECN moisture absorption and absored water dominantly existed in the form of combined water. Magnetic resonance imaging (MRI) and MIR spectroscopy results indicated that moisture absorption could change the morphology and structure of SHECN. After moisture absorption at 50% and 75% relative humidity, 19 volatiles were identified by GC-MS analysis. Additionally, this study showed that a part of reductive groups in SHECN was oxidized and its antioxidant ability declined significantly (P < 0.05) after moisture absorption.

CONCLUSION

Water absorbed into SHECN powder can significantly change its microstructure and cause its activity to decrease. We must prevent SHECN from absorbing moisture during storage because the water can accelerate the oxidation of samples and promote microbial reactions. © 2016 Society of Chemical Industry.

Potential role of bioactive peptides in prevention and treatment of chronic diseases: a narrative review

In the past few years, increasing interest has been directed to bioactive peptides of animal and plant origin: in particular, researchers have focused their attention on their mechanisms of action and potential role in the prevention and treatment of cancer, cardiovascular and infective diseases. We have developed a search strategy to identify these studies in PubMed (January 1980 to May 2016); particularly those papers presenting comprehensive reviews or meta-analyses, plus in vitro and in vivo studies and clinical trials on those bioactive peptides that affect cardiovascular diseases, immunity or cancer, or have antioxidant, anti-inflammatory and antimicrobial effects. In this review we have mostly focused on evidence-based healthy properties of bioactive peptides from different sources. Bioactive peptides derived from fish, milk, meat and plants have demonstrated significant antihypertensive and lipid-lowering activity in clinical trials. Many bioactive peptides show selective cytotoxic activity against a wide range of cancer cell lines in vitro and in vivo, whereas others have immunomodulatory and antimicrobial effects. Furthermore, some peptides exert anti-inflammatory and antioxidant activity, which could aid in the prevention of chronic diseases. However, clinical evidence is at an early stage, and there is a need for solid pharmacokinetic data and for standardized extraction procedures. Further studies on animals and randomized clinical trials are required to confirm these effects, and enable these peptides to be used as preventive or therapeutic treatments.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Lunasin: A promising polypeptide for the prevention and treatment of cancer

Strategies for the treatment of cancer remain unsatisfactory due to the poor understanding of the complicated underlying molecular mechanisms of carcinogenesis. A number of types of cancer exhibit a marked association with dietary habits and lifestyles. Therefore, the modulation of dietary habits or lifestyles may be an effective strategy for preventing the formation and progression of cancer. Proteins and polypeptides from soybean have been developed as healthcare products due to their marked activity in inhibiting the progression of cancer at various stages. Lunasin, containing 43 amino acid residues, is one such example of a soybean-derived polypeptide that has been demonstrated to exhibit marked anti-cancer activity. In the present review, studies of the underlying molecular mechanisms and potential advantages of lunasin in the prevention and treatment of cancer have been examined, to provide a theoretical reference for the development of natural product-based agents or healthcare products for the prevention and treatment of cancer.

Isolation and identification of anti-proliferative peptides from Spirulina platensis using three-step hydrolysis

BACKGROUND

Spirulina platensis is an excellent source of proteins (>60%) that can be hydrolyzed into bioactive peptides.

RESULTS

In this study, whole proteins of Spirulina platensis were extracted and hydrolyzed using three gastrointestinal endopeptidases (pepsin, trypsin and chymotrypsin). Subsequently, gel filtration chromatography was employed to separate hydrolysates, and four fractions (Tr1-Tr4) were obtained. Among them, Tr2 showed the strongest anti-proliferation activities on three cancer cells (MCF-7, HepG-2 and SGC-7901), with IC₅₀ values of <31.25, 36.42 and 48.25 µg mL^-1 , respectively. Furthermore, a new peptide, HVLSRAPR, was identified from fraction Tr1. This peptide exhibited strong inhibition on HT-29 cancer cells with an IC₅₀ value of 99.88 µg mL^-1 .

CONCLUSION

Taken together, these peptides possessed anti-proliferation activities on cancer cells and low cytotoxicity on normal cells, suggesting that they might serve as a natural anticancer agent for nutraceutical and pharmaceutical industries. © 2016 Society of Chemical Industry.

Lunasin is a redox sensitive intrinsically disordered peptide with two transiently populated α-helical regions

Lunasin is a 43 amino acid peptide with anti-cancer, antioxidant, anti-inflammatory and cholesterol-lowering properties. Although the mechanism of action of lunasin has been characterized to some extent, its exact three-dimensional structure as well as the function of the N-terminal sequence remains unknown. We established a novel method for the production of recombinant lunasin that allows efficient isotope labeling for NMR studies. Initial studies showed that lunasin can exist in a reduced or oxidized state with an intramolecular disulfide bond depending on solution conditions. The structure of both forms of the peptide at pH 3.5 and 6.5 was characterized by CD spectroscopy and multidimensional NMR methods. The data indicate that lunasin belongs to the class of intrinsically disordered proteins. The analysis of secondary structure propensities indicates the presence of two helical regions and an extended (beta strand) conformation at the C-terminus. We hypothesize that the transient secondary structure elements could be stabilized upon interaction with the histones H3 and H4. The newly discovered redox properties of lunasin could explain its antioxidant and anti-inflammatory activity.

The potential of food protein-derived anti-inflammatory peptides against various chronic inflammatory diseases

Inflammation is considered as one of the major causes for the initiation of various chronic diseases such as asthma, cancer, cardiovascular disease, diabetes, obesity, inflammatory bowel disease, osteoporosis and neurological diseases like Parkinson's disease. Increasing scientific evidence has delineated that inflammatory markers such as TNF-α, IL-1, IL-6, IL-8 and CRP and different transcription factors such as NF-κB and STAT are the major key factors that regulate these inflammatory diseases. Food protein-derived bioactive peptides have been shown to exhibit anti-inflammatory activity by inhibiting or reducing the expression of these inflammatory biomarkers and/or by modulating the activity of these transcription factors. This review aims to discuss various molecular targets and underlying mechanisms of food protein-derived anti-inflammatory peptides and to explore their potential against various chronic inflammatory diseases. © 2015 Society of Chemical Industry.

Inhibitory effects of small molecular peptides from Spirulina (Arthrospira) platensis on cancer cell growth

Anti-proliferation activities of the identified peptide YGFVMPRSGLWFR.

The protective role of the Bowman-Birk protease inhibitor in soybean lunasin digestion: the effect of released peptides on colon cancer growth

Lunasin is a naturally-occurring peptide demonstrating chemopreventive, antioxidant and anti-inflammatory properties. To exhibit these activities, orally ingested lunasin needs to survive proteolytic attack of digestive enzymes to reach target tissues in active form/s. Preliminary studies suggested the protective role of protease inhibitors, such as the Bowman-Birk inhibitor and Kunitz-trypsin inhibitor, against lunasin's digestion by both pepsin and pancreatin. This work describes in depth the behaviour of lunasin under conditions simulating the transit through the gastrointestinal tract in the absence or presence of soybean Bowman-Birk isoinhibitor 1 (IBB1) in both active and inactive states. By liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), the remaining lunasin at the end of gastric and gastro-duodenal phases was quantified. Protection against the action of pepsin was independent of the amount of IBB1 present in the analyzed samples, whereas an IBB1 dose-dependent protective effect against trypsin and chymotrypsin was observed. Peptides released from lunasin and inactive IBB1 were identified by MS/MS. The remaining lunasin and IBB1 as well as their derived peptides could be responsible for the anti-proliferative activity against colon cancer cells observed for the digests obtained at the end of simulated gastrointestinal digestion.

Lunasin alleviates allergic airway inflammation while increases antigen-specific Tregs

Lunasin is a naturally occurring peptide isolated from soybeans and has been explored in cancer treatment. Lunasin inhibits NF-κB activation and thus pro-inflammatory cytokine and mediator production in macrophages. In this study we demonstrate that lunasin can effectively suppress allergic airway inflammation in two murine models of asthma. In an OVA+Alum sensitization model, intranasal lunasin treatment at the time of OVA challenges significantly reduced total cells counts in bronchoalveolar lavage (BAL) fluid and eosinophilia, peribronchiolar inflammatory infiltration, goblet cell metaplasia and airway IL-4 production. In an OVA+LPS intranasal sensitization model, lunasin treatment either at the time of sensitization or challenge has similar effects in suppress allergic airway inflammation including significantly reduced total cell and eosinophil counts in BAL fluid, inflammatory gene Fizz1 expression in the lung, and IL-4 production by OVA re-stimulated cells from mediastinal lymph nodes. We further show that intranasal instillation of OVA+lunasin significantly increases OVA-specific regulatory T cell (Treg) accumulation in the lung comparing to OVA only treatment. Taken together, our results suggest lunasin as an anti-inflammatory agent can be potentially used in asthma therapy or as an adjuvant to enhance the induction of antigen-specific Tregs and thus boost the efficacy of allergy immunotherapy.

Antiproliferative effect of Dendrobium catenatum Lindley polypeptides against human liver, gastric and breast cancer cell lines

Ten sub-peptides from Dendrobium catenatum Lindley contained in fraction A3 were separated. Fraction A3 exhibited anti-proliferative activity against cancer cells.

Efficient production of native lunasin with correct N-terminal processing by using the pH-induced self-cleavable Ssp DnaB mini-intein system in Escherichia coli

To develop an efficient and cost-effective approach for the production of small preventive peptide lunasin with correct natural N terminus, a synthetic gene was designed by OPTIMIZER & Gene Designer and cloned into pTWIN1 vector at SapI and PstI sites. Thus, lunasin was N-terminally fused to the pH-induced self-cleavable Ssp DnaB mini-intein linked to a chitin binding domain (CBD) with no extra residues. The resultant fusion protein was highly expressed by lactose induction in Escherichia coli BL21 (DE3) in a 7-l bioreactor and bound to a chitin affinity column. After washing the impurities, the Ssp DnaB intein mediated on-column self-cleavage was easily triggered by shifting pH and temperature to allow the native lunasin released. The final purified lunasin yielded up to 75 mg/l medium. Tricine/SDS-PAGE and matrix-assisted laser desorption time-of-flight (MALDI-TOF)/mass spectrometry (MS) verified the structural authenticity of the product, implying the correct cleavage at the junction between Ssp DnaB intein and lunasin. MTT assay confirmed its potent proliferation inhibitory activity to human cancer cells HCT-116 and MDA-MB-231; however, no cytotoxicity to normal human lens epithelial cell SRA01/04 and hepatoma HepG2. Taken together, we provide a novel strategy to produce recombinant native lunasin with correct N-terminal processing by using the pH-induced self-cleavable Ssp DnaB mini-intein.

Functional significance of bioactive peptides derived from soybean

Biologically active peptides play an important role in metabolic regulation and modulation. Several studies have shown that during gastrointestinal digestion, food processing and microbial proteolysis of various animals and plant proteins, small peptides can be released which possess biofunctional properties. These peptides are to prove potential health-enhancing nutraceutical for food and pharmaceutical applications. The beneficial health effects of bioactive peptides may be several like antihypertensive, antioxidative, antiobesity, immunomodulatory, antidiabetic, hypocholesterolemic and anticancer. Soybeans, one of the most abundant plant sources of dietary protein, contain 36-56% of protein. Recent studies showed that soy milk, an aqueous extract of soybean, and its fermented product have great biological properties and are a good source of bioactive peptides. This review focuses on bioactive peptides derived from soybean; we illustrate their production and biofunctional attributes.

Four conventional soybean [Glycine max (L.) Merrill] seeds exhibit different protein profiles as revealed by proteomic analysis

Soybeans have several functional properties due to their composition and may exert beneficial health effects that are attributed to proteins and their derivative peptides. The present study aimed to analyze the protein profiles of four new conventional soybean seeds (BRS 257, BRS 258, BRS 267, and Embrapa 48) with the use of proteomic tools. Two-dimensional (2D) and one-dimensional (1D) gel electrophoreses were performed, followed by MALDI-TOF/TOF and ESI-Q-TOF mass spectrometry analyses, respectively. These two different experimental approaches allowed the identification of 117 proteins from 1D gels and 46 differentially expressed protein spots in 2D gels. BRS 267 showed the greatest diversity of identified spots in the 2D gel analyses. In the 1D gels, the major groups were storage (25-40%) and lipid metabolism (11-25%) proteins. The differences in protein composition between cultivars could indicate functional and nutritional differences and could direct the development of new cultivars.

Cholesterol-lowering Effect of Rice Protein by Enhancing Fecal Excretion of Lipids in Rats

The aim of this study was to investigate the effects of isolated protein from white rice on lipid metabolism in a hypercholesterolemic animal model. Male Sprague-Dawley rats were divided into three groups and fed either a normal diet or a high-cholesterol diet (HCD) containing either casein or isolated rice protein for 4 weeks. Compared with rats fed a HCD with casein, the total cholesterol (TC) level in the plasma was significantly reduced in the rats fed rice protein. However, no significant differences were observed in the triglycerides, high-density lipoprotein (HDL), and glucose levels among the experimental groups. Hepatic total lipids and TC levels were significantly decreased by supplementation with rice protein. In addition, rice protein significantly increased the levels of TC and bile acids in the feces. These results suggest that rice protein may improve HCD-induced hypercholesterolemia by enhancing fecal excretion of cholesterol.

Current scenario of peptide-based drugs: the key roles of cationic antitumor and antiviral peptides

Cationic antimicrobial peptides (AMPs) and host defense peptides (HDPs) show vast potential as peptide-based drugs. Great effort has been made in order to exploit their mechanisms of action, aiming to identify their targets as well as to enhance their activity and bioavailability. In this review, we will focus on both naturally occurring and designed antiviral and antitumor cationic peptides, including those here called promiscuous, in which multiple targets are associated with a single peptide structure. Emphasis will be given to their biochemical features, selectivity against extra targets, and molecular mechanisms. Peptides which possess antitumor activity against different cancer cell lines will be discussed, as well as peptides which inhibit virus replication, focusing on their applications for human health, animal health and agriculture, and their potential as new therapeutic drugs. Moreover, the current scenario for production and the use of nanotechnology as delivery tool for both classes of cationic peptides, as well as the perspectives on improving them is considered.

Structural property of soybean lunasin and development of a method to quantify lunasin in plasma using an optimized immunoassay protocol

Lunasin is a 43-amino acid naturally occurring chemopreventive peptide with demonstrated anti-cancer and anti-inflammatory properties. The objectives of this study were to determine the effect of temperature on the secondary structure of lunasin, to develop a method of isolating lunasin from human plasma using an ion-exchange microspin column and to quantify the amount of lunasin using an optimized enzyme-linked immunosorbent assay. Lunasin was purified using a combination of ion-exchange chromatography, ultrafiltration and gel filtration chromatography. Circular dichroism showed that increased in temperature from 25 to 100 °C resulted in changes on the secondary structure of lunasin and its capability to interact with rabbit polyclonal antibody. Enzyme linked immunosorbent assay showed that lunasin rabbit polyclonal antibody has a titer of 250 and a specific activity of 0.05 mL/μg. A linear response was detected between 16 to 48 ng lunasin per mL (y=0.03x-0.38, R(2)=0.96). The use of diethylaminoethyl microspin column to isolate spiked lunasin in human plasma showed that most lunasin (37.8-46.5%) bound to the column eluted with Tris-HCl buffer, pH 7.5 with a yield up to 76.6%. In conclusion, lunasin can be isolated from human plasma by a simple DEAE microspin column technique and can be quantified using a validated and optimized immunoassay procedure. This method can be used directly to quantify lunasin from plasma in different human and animal studies aiming to determine its bioavailability.

Separation, antitumor activities, and encapsulation of polypeptide from Chlorella pyrenoidosa

Chlorella pyrenoidosa is a unicellular green algae and has been a popular foodstuff worldwide. However, no reports on the antitumor peptides from such a microalgae are available in the literature. In this study, using low-temperature high-pressure extraction, enzymatic hydrolysis, ion exchange, and gel filtration chromatography, we separated a polypeptide that exhibited inhibitory activity on human liver cancer HepG2 cells, and named the polypeptide CPAP (C. pyrenoidosa antitumor polypeptide). Furthermore, the micro- and nanoencapsulation of CPAP were investigated by using two methods: complex coacervation and ionotropic gelation. The in vitro release tests revealed that CPAP was well preserved against gastric enzymatic degradation after micro/nanoencapsulation and the slowly controlled release in the intestine could be potentially achieved. These results suggest that CPAP may be a useful ingredient in food, nutraceutical, and pharmaceutical applications.

The soybean peptide lunasin promotes apoptosis of mammary epithelial cells via induction of tumor suppressor PTEN: similarities and distinct actions from soy isoflavone genistein

Breast cancer is the leading cause of cancer deaths in women. Diet and lifestyle are major contributing factors to increased breast cancer risk. While mechanisms underlying dietary protection of mammary tumor formation are increasingly elucidated, there remains a dearth of knowledge on the nature and precise actions of specific bioactive components present in foods with purported health effects. The 43-amino acid peptide lunasin (LUN) is found in soybeans, is bioavailable similar to the isoflavone genistein (GEN), and thus may mediate the beneficial effects of soy food consumption. Here, we evaluated whether LUN displays common and distinct actions from those of GEN in non-malignant (mouse HC11) and malignant (human MCF-7) mammary epithelial cells. In MCF-7 cells, LUN up-regulated tumor suppressor phosphatase and tensin homolog deleted in chromosome ten (PTEN) promoter activity, increased PTEN transcript and protein levels and enhanced nuclear PTEN localization, similar to that shown for GEN in mammary epithelial cells. LUN-induced cellular apoptosis, akin to GEN, was mediated by PTEN, but unlike that for GEN, was p53-independent. LUN promoted E-cadherin and β-catenin non-nuclear localization similar to GEN, but unlike GEN, did not influence the proliferative effects of oncogene Wnt1 on HC11 cells. Further, LUN did not recapitulate GEN inhibitory effects on expansion of the cancer stem-like/progenitor population in MCF-7 cells. Results suggest the concerted actions of GEN and LUN on cellular apoptosis for potential mammary tumor preventive effects and highlight whole food consumption rather than intake of specific dietary supplements with limited biological effects for greater health benefits.

Dietary modification of metabolic pathways via nuclear hormone receptors

Nuclear hormone receptors (NHRs), as ligand-dependent transcription factors, have emerged as important mediators in the control of whole body metabolism. Because of the promiscuous nature of several members of this superfamily that have been found to bind ligand with lower affinity than the classical steroid NHRs, they consequently display a broader ligand selectivity. This promiscuous nature has facilitated various bioactive dietary components being able to act as agonist ligands for certain members of the NHR superfamily. By binding to these NHRs, bioactive dietary components are able to mediate changes in various metabolic pathways, including, glucose, cholesterol and triglyceride homeostasis among others. This review will provide a general overview of the nuclear hormone receptors that have been shown to be activated by dietary components. The physiological consequences of such receptor activation by these dietary components will then be discussed in more detail.

Recombinant production of the therapeutic peptide lunasin

Background

Lunasin is a chemopreventive peptide produced in a number of plant species. It comprises a helical region with homology to a region of chromatin binding proteins, an Arg-Gly-Asp cell adhesion motif and eight aspartic acid residues. In vitro studies indicate that lunasin suppresses chemical and oncogene driven transformation of mammalian cells. We have explored efficient recombinant production of lunasin by exploiting the Clostridium thermocellum CipB cellulose binding domain (CBD) as a fusion partner protein.

Results

We used a pET28 vector to express a CBD-lunasin fusion with a hexahistidine tag and Tobacco Etch Virus protease site, to allow protease-mediated release of native lunasin. Autoinduction in E. coli BL21 (DE3) Star cells achieved expression of 3.35 g/L of CBD-lunasin fusion protein. The final yield of lunasin was 210 mg/L corresponding to 32% of the theoretical yield. Purification by cellulose binding and nickel affinity chromatography were tested with the latter proving more satisfactory.

The effects of CBD-lunasin expression on growth and morphology of the E. coli cells were examined by light and electron microscopy revealing an altered morphology in a proportion of cells. Cell division appeared to be inhibited in these cells resulting in elongated, non-septated cells.

Conclusions

The use of CBD as a fusion partner gave high protein yields by autoinduction, with lunasin release by TEV protease cleavage. With some optimisation this approach could provide a potentially valuable route for production of this therapeutic peptide. Over-expression in the host cells manifest as a cell division defect in a population of the cells, presumably mimicking some aspect of the chemopreventive function observed in mammalian cells.

Lunasin potentiates the effect of oxaliplatin preventing outgrowth of colon cancer metastasis, binds to α5β1 integrin and suppresses FAK/ERK/NF-κB signaling

The effect of lunasin on colon cancer metastasis was studied using three human colon cancer cell lines in vitro and a liver metastasis model of colon cancer in vivo. Lunasin bound with α5β1 integrin and internalized into the nucleus of KM12L4 human colon cancer cells. Lunasin (10 μM) inhibited the activation of focal adhesion kinase (FAK) by 28%, 39% and 60% in RKO, HCT-116 and KM12L4 human colon cancer cells, respectively. Lunasin caused an increase in the expression of the inhibitor of kappa B alpha (IκB-α), a decrease in nuclear p50 NF-κB and a reduction in the migration of cancer cells. Lunasin (4 mg/kg bw) inhibited metastasis and potentiated the effect of oxaliplatin by reducing the expression of proliferating cell nuclear antigen. Liver metastatic nodules were reduced from 28 (PBS) to 14 (lunasin, P = 0.047) while combination of lunasin and oxaliplatin to 5 (P = 0.004). The tumor burden was reduced from 0.13 (PBS) to 0.10 (lunasin, P = 0.039) to 0.04 (lunasin + oxaliplatin, P < 0.0001). Moreover, lunasin potentiated the effect of oxaliplatin in modifying expression of proteins involved in apoptosis and metastasis including Bax, Bcl-2, IKK-α and p-p65. Lunasin inhibited metastasis of human colon cancer cells by direct binding with α5β1 integrin suppressing FAK/ERK/NF-κB signaling, and potentiated the effect of oxaliplatin in preventing the outgrowth of metastasis.

Lunasin-aspirin combination against NIH/3T3 cells transformation induced by chemical carcinogens

Carcinogenesis is a multistage process involving a number of molecular pathways sensitive to intervention. Chemoprevention is defined as the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. To achieve greater inhibitory effects on cancer cells, combination of two or more chemopreventive agents is commonly considered as a better preventive and/or therapeutic strategy. Lunasin is a promising cancer preventive peptide identified in soybean and other seeds. Its efficacy has been demonstrated by both in vitro and in vivo models. This peptide has been found to inhibit human breast cancer MDA-MB-231 cells proliferation, suppressing cell cycle progress and inducing cell apoptosis. Moreover, lunasin potentiates the effects on these cells of different synthetic and natural compounds, such as aspirin and anacardic acid. This study explored the role of lunasin, alone and in combination with aspirin and anacardic acid on cell proliferation and foci formation of transformed NIH/3T3 cells induced by chemical carcinogens 7,12-dimethylbenz[a]anthracene or 3-methylcholanthrene. The results revealed that lunasin, acting as a single agent, inhibits cell proliferation and foci formation. When combined with aspirin, these effects were significantly increased, indicating that this combination might be a promising strategy to prevent/treat cancer induced by chemical carcinogens.