Hypocholesterolaemic Activity of Lupin Peptides: Investigation on the Crosstalk between Human Enterocytes and Hepatocytes Using a Co-Culture System Including Caco-2 and HepG2 Cells

Comprehensive review of plant-derived anti-hyperlipidemia peptides: Production, anti-hyperlipidemia mechanism, and structure-activity relationship study

Hyperlipidemia, an elevated level of cholesterol and/or triglycerides, has become a major public health problem worldwide. Although drugs intervention is effective in treating hyperlipidemia, most of them have adverse side effects. Peptides from natural plants with high anti-hyperlipidemic activity and a strong safety profile have emerged as promising candidates to prevent and ameliorate hyperlipidemia. This review summarizes the recent advances in plant-derived anti-hyperlipidemic peptides in terms of their sources, production, purification, identification, and activity evaluation. The focus is extended to their potential anti-hyperlipidemic mechanisms and structure-function relationships. Bioactive peptides derived from various plant sources, especially peptides containing hydrophobic and/or acidic amino acids, have shown remarkable effects in hyperlipidemic treatment. Their anti-hyperlipidemic effects are mediated by various mechanisms, including regulation of cholesterol metabolism and triglyceride metabolism, inhibition of inflammation-related metabolic syndrome, and modulation of the gut microbiota. Further evaluation of the stability, bioavailability, and clinical efficacy of these peptides is recommended.

The in vitro intestinal cell model: different co-cultured cells create different applications

As a vitro absorption model, the Caco-2 cells originate from a human colon adenocarcinomas and can differentiate into a cell layer with enterocyte-like features. The Caco-2 cell model is popularly applied to explore drug transport mechanisms, to evaluate the permeability of drug and to predict the absorption of drugs or bioactive substances in the gut. However, there are limitations to the application of Caco-2 cell model due to lack of a mucus layer, the long culture period and the inability to accurately simulate the intestinal environment. The most frequent way to expand the Caco-2 cell model and address its limitations is by co-culturing it with other cells or substances. This article reviews the culture methods and applications of 3D and 2D co-culture cell models established around Caco-2 cells. It also concludes with a summary of model strengths and weaknesses.

Plant bioactive peptides for cardiovascular disease prevention

Cardiovascular disease (CVD) is a major cause of deaths in industrialized countries and a constantly growing cause of morbidity and mortality worldwide Hypercholesterolemia is one of the main risk factors for CVD progression that may be prevented by lifestyle changes, including diet. This chapter will discuss the role of peptides from plants (soybean, lupin, cowpea, hempseed, and rice bran) sources with pleotropic activity for the prevention of CVD. Overall, the bioactivity that will be mainly discussed it is the hypocholesterolemic one. The very diversified structures of the hypocholesterolemic peptides so far identified explains the reason why they exert their activity through different mechanisms of action that will be extensively described in this review. Doubtlessly, their potential use in nutritional application is desirable, however, only few of them have been tested in vivo. Therefore, more efforts need to be pursued for singling out good candidates for the development of functional foods or dietary supplements.

Chemical and biological characterization of the DPP-IV inhibitory activity exerted by lupin (Lupinus angustifolius) peptides: From the bench to the bedside investigation

Dipeptidyl peptidase IV (DPP-IV) is considered a key target for the diabetes treatment, since it is involved in glucose metabolism. Although lupin protein consumption shown hypoglycemic activity, there is no evidence of its effect on DPP-IV activity. This study demonstrates that a lupin protein hydrolysate (LPH), obtained by hydrolysis with Alcalase, exerts anti-diabetic activity by modulating DPP-IV activity. In fact, LPH decreased DPP-IV activity in a cell-free and cell-based system. Contextually, Caco-2 cells were employed to identify LPH peptides that can be intestinally trans-epithelial transported. Notably, 141 different intestinally transported LPH sequences were identified using nano- and ultra-chromatography coupled to mass spectrometry. Hence, it was demonstrated that LPH modulated the glycemic response and the glucose concentration in mice, by inhibiting the DPP-IV. Finally, a beverage containing 1 g of LPH decreased DPP-IV activity and glucose levels in humans.

Evaluation of the multifunctional dipeptidyl-peptidase IV and angiotensin converting enzyme inhibitory properties of a casein hydrolysate using cell-free and cell-based assays

The objective of the study was the evaluation of the potential pleiotropic effect of a commercial casein hydrolysate (CH). After an analysis of the composition, the BIOPEP-UWM database suggested that these peptides contained numerous sequences with potential inhibitory activities on angiotensin converting enzyme (ACE) and dipeptidyl-peptidase IV (DPP-IV). The anti-diabetic and anti-hypertensive effects of these peptides were thus assessed using either cell-free or cell-based assays. In the cell-free system, CH displayed inhibitory properties against DPP-IV (IC₅₀ value equal to 0.38 ± 0.01 mg/mL) and ACE (IC₅₀ value equal to 0.39 ± 0.01 mg/mL). Further, CH reduced the DPP-IV and ACE activities expressed by human intestinal Caco-2 cells by 61.10 ± 1.70% and 76.90 ± 4.47%, respectively, versus untreated cells, after 6 h of treatment at the concentration of 5 mg/mL. This first demonstration of the multifunctional behavior of this material suggests that it may become an anti-diabetic and/or anti-hypertensive ingredient to be included in the formulation of different functional food or nutraceutics.

Carboxymethyl Cellulose as a Food Emulsifier: Are Its Days Numbered?

Carboxymethyl cellulose use in industry is ubiquitous. Though it is recognized as safe by the EFSA and FDA, newer works have raised concerns related to its safety, as in vivo studies showed evidence of gut dysbiosis associated with CMC's presence. Herein lies the question, is CMC a gut pro-inflammatory compound? As no work addressed this question, we sought to understand whether CMC was pro-inflammatory through the immunomodulation of GI tract epithelial cells. The results showed that while CMC was not cytotoxic up to 25 mg/mL towards Caco-2, HT29-MTX and Hep G2 cells, it had an overall pro-inflammatory behavior. In a Caco-2 monolayer, CMC by itself increased IL-6, IL-8 and TNF-α secretion, with the latter increasing by 1924%, and with these increases being 9.7 times superior to the one obtained for the IL-1β pro-inflammation control. In co-culture models, an increase in secretion in the apical side, particularly for IL-6 (692% increase), was observed, and when RAW 264.7 was added, data showed a more complex scenario as stimulation of pro-inflammatory (IL-6, MCP-1 and TNF-α) and anti-inflammatory (IL-10 and IFN-β) cytokines in the basal side was observed. Considering these results, CMC may exert a pro-inflammatory effect in the intestinal lumen, and despite more studies being required, the incorporation of CMC in foodstuffs must be carefully considered in the future to minimize potential GI tract dysbiosis.

Potential Role of Bioactive Proteins and Peptides Derived from Legumes towards Metabolic Syndrome

Legumes have been widely consumed and used to isolate bioactive compounds, mainly proteins. The aim of this study was to review the beneficial actions of different legumes proteins and peptides updating the main findings that correlate legumes consumption and the effects on non-transmissible chronic diseases, specifically metabolic syndrome. An exhaustive revision of five relevant bioactivities (antioxidant, anti-inflammatory, antihypertensive, hypocholesterolemic -all of them linked to metabolic syndrome- and antitumoral) of proteins and peptides from legumes focused on isolation and purification, enzymatic hydrolysis and in vitro gastrointestinal digestion was carried out. The promising potential of bioactive hydrolysates and peptides from pulses has been demonstrated by in vitro tests. However, only a few studies validated these biological activities using animal models. No clinical trials have been carried out yet; so further research is required to elucidate their effective health implications.

Bioactive and health-promoting properties of enzymatic hydrolysates of legume proteins: a review

This study comprehensively reviewed the effect of controlled enzymatic hydrolysis on the bioactivity of pulse protein hydrolysates (PPHs). Proteolysis results in the partial structural unfolding of pulse proteins with an increase in buried hydrophobic groups of peptide sequences. The use of PPHs in a dose-dependent manner can enhance free radical scavenging and improve antioxidant activities regarding inhibition of lipid oxidation, ferric reducing power, metal ion chelation, and β-carotene bleaching inhibition. Ultrafiltered peptide fractions with low molecular weights imparted angiotensin-I converting enzyme (ACE) inhibitory effects during in vitro simulated gastrointestinal digestion and in vivo conditions. Ultrasonication, high-pressure pretreatments, and glycosylation as post-treatments can improve the antiradical, antioxidant, and ACE inhibitory activities of PPHs. The electrostatic attachment of pulse peptides to microbial cells can inhibit the growth and activity of bacteria and fungi. Bioactive pulse peptides can reduce serum cholesterol and triglycerides, and inhibit the formation of adipocyte lipid storage, allergenic factors, inflammatory markers, and arterial thrombus without cytotoxicity. The combination of germination and enzymatic hydrolysis can significantly increase the protein digestibility and bioavailability of essential amino acids. Moreover, the utilization and enrichment of bakery and meat products with functional PPHs ensure quality, safety, and health aspects of food products.

Bioactive Peptides from Lupin (Lupinus angustifolius) Prevent the Early Stages of Atherosclerosis in Western Diet-Fed ApoE-/- Mice

We have previously reported the in vitro hypocholesterolemic, anti-inflammatory, and antioxidant effects of Alcalase-generated lupin protein hydrolysate (LPH). Given that lipoprotein deposition, oxidative stress, and inflammation are the main components of atherogenesis, we characterized the LPH composition, in silico identified LPH-peptides with activities related to atherosclerosis, and evaluated the in vivo LPH effects on atherosclerosis risk factors in a mouse model of atherosclerosis. After 15 min of Alcalase hydrolysis, peptides smaller than 8 kDa were obtained, and 259 peptides out of 278 peptides found showed biological activities related to atherosclerosis risk factors. Furthermore, LPH administration for 12 weeks reduced the plasma lipids, as well as the cardiovascular and atherogenic risk indexes. LPH also increased the total antioxidant capacity, decreased endothelial permeability, inflammatory response, and atherogenic markers. Therefore, this study describes for the first time that LPH prevents the early stages of atherosclerosis.

Integrated Evaluation of the Multifunctional DPP-IV and ACE Inhibitory Effect of Soybean and Pea Protein Hydrolysates

Nowadays, notwithstanding their nutritional and technological properties, food bioactive peptides from plant sources garner increasing attention for their ability to impart more than one beneficial effect on human health. Legumes, which stand out thanks to their high protein content, represent valuable sources of bioactive peptides. In this context, this study focused on the characterization of the potential pleotropic activity of two commercially available soybean (SH) and pea (PH) protein hydrolysates, respectively. Since the biological activity of a specific protein hydrolysate is strictly correlated with its chemical composition, the first aim of the study was to identify the compositions of the SH and PH peptides. Peptidomic analysis revealed that most of the identified peptides within both mixtures belong to storage proteins. Interestingly, according to the BIOPEP-UWM database, all the peptides contain more than one active motive with known inhibitory angiotensin converting enzyme (ACE) and dipeptidyl-dipeptidases (DPP)-IV sequences. Indeed, the results indicated that both SH and PH inhibit DPP-IV and ACE activity with a dose-response trend and IC50 values equal to 1.15 ± 0.004 and 1.33 ± 0.004 mg/mL, and 0.33 ± 0.01 and 0.61 ± 0.05 mg/mL, respectively. In addition, both hydrolysates reduced the activity of DPP-IV and ACE enzymes which are expressed on the surface of human intestinal Caco-2 cells. These findings clearly support that notion that SH and PH may represent new ingredients with anti-diabetic and hypotensive effects for the development of innovative multifunctional foods and/or nutraceuticals for the prevention of metabolic syndrome.

Antitumor activity and molecular mechanism of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a member of the proprotein convertase family of proteins that activate other proteins in cells. Functionally, PCSK9 binds to the receptor of low-density lipoprotein particles (LDL) to regulate cholesterol metabolism and lipoprotein homeostasis in human body. PCSK9 inhibition is a novel pharmacological strategy to control hypercholesterolemia and cardiovascular diseases. Recently accumulating evidence realizes that PCSK9 possesses other roles in cells, such as regulation of tissue inflammatory response, intratumoral immune cell infiltration, and tumor progression. This review discussed the advancement of PCSK9 research on its role and underlying mechanisms in tumor development and progression. For example, PCSK9 inhibition could attenuate progression of breast cancer, glioma, colon tumor, hepatocellular cancer, prostate cancer, and lung adenocarcinoma and promote apoptosis of glioma, prostate cancer, and hepatocellular cancer cells. PCSK9 deficiency could reduce liver metastasis of B16F1 melanoma cells by lowering the circulating cholesterol levels. PCSK9 gene knockdown substantially attenuated mouse tumor growth in vivo by activation of cytotoxic T cells, although PCSK9 knockdown had no effect on morphology and growth rate of different mouse cancer cell lines in vitro. PCSK9 inhibition thus can be used to control human cancers. Future preclinical and clinical studies are warranted to define anti-tumor activity of PCSK9 inhibition.

Hempseed (Cannabis sativa) Peptide H3 (IGFLIIWV) Exerts Cholesterol-Lowering Effects in Human Hepatic Cell Line

Hempseed (Cannabis sativa) protein is an important source of bioactive peptides. H3 (IGFLIIWV), a transepithelial transported intestinal peptide obtained from the hydrolysis of hempseed protein with pepsin, carries out antioxidant and anti-inflammatory activities in HepG2 cells. In this study, the main aim was to assess its hypocholesterolemic effects at a cellular level and the mechanisms behind this health-promoting activity. The results showed that peptide H3 inhibited the 3-hydroxy-3-methylglutaryl co-enzyme A reductase (HMGCoAR) activity in vitro in a dose-dependent manner with an IC50 value of 59 μM. Furthermore, the activation of the sterol regulatory element binding proteins (SREBP)-2 transcription factor, followed by the increase of low-density lipoprotein (LDL) receptor (LDLR) protein levels, was observed in human hepatic HepG2 cells treated with peptide H3 at 25 µM. Meanwhile, peptide H3 regulated the intracellular HMGCoAR activity through the increase of its phosphorylation by the activation of AMP-activated protein kinase (AMPK)-pathways. Consequently, the augmentation of the LDLR localized on the cellular membranes led to the improved ability of HepG2 cells to uptake extracellular LDL with a positive effect on cholesterol levels. Unlike the complete hempseed hydrolysate (HP), peptide H3 can reduce the proprotein convertase subtilisin/kexin 9 (PCSK9) protein levels and its secretion in the extracellular environment via the decrease of hepatic nuclear factor 1-α (HNF1-α). Considering all these evidences, H3 may represent a new bioactive peptide to be used for the development of dietary supplements and/or peptidomimetics for cardiovascular disease (CVD) prevention.

A Lupinus angustifolius protein hydrolysate exerts hypocholesterolemic effects in Western diet-fed ApoE-/- mice through the modulation of LDLR and PCSK9 pathways

Lupin protein hydrolysates (LPHs) are gaining attention in the food and nutraceutical industries due to their several beneficial health effects. Recently, we have shown that LPH treatment reduces liver cholesterol and triglyceride levels in hypercholesterolemic mice. The aim of this study was to elucidate the effects of LPH treatment on the molecular mechanism underlying liver cholesterol metabolism in ApoE^-/- mice fed the Western diet. After identifying the composition of the peptide within the LPH mixture and determining its ability to reduce HMGCoAR activity in vitro, its effect on the LDLR and PCSK9 pathways was measured in liver tissue from the same mice. Thus, the LPH reduced the protein levels of HMGCoAR and increased the phosphorylated inactive form of HMGCoAR and the pHMGCoAR/HMGCoAR ratio, which led to the deactivation of de novo cholesterol synthesis. Furthermore, the LPH decreased the protein levels of SREBP2, a key upstream transcription factor involved in the expression of HMGCoAR and LDLR. Consequently, LDLR protein levels decreased in the liver of LPH-treated animals. Interestingly, the LPH also increased the protein levels of pAMPK responsible for HMGCoAR phosphorylation. Furthermore, the LPH controlled the PSCK9 signal pathway by decreasing its transcription factor, the HNF1-α protein. Consequently, lower PSCK9 protein levels were found in the liver of LPH-treated mice. This is the first study elucidating the molecular mechanism at the basis of the hypocholesterolemic effects exerted by the LPH in an in vivo model. All these findings point out LPHs as a future lipid-lowering ingredient to develop new functional foods.

Computational Design and Biological Evaluation of Analogs of Lupin Peptide P5 Endowed with Dual PCSK9/HMG-CoAR Inhibiting Activity

(1) Background: Proprotein convertase subtilisin/kexin 9 (PCSK9) is responsible for the degradation of the hepatic low-density lipoprotein receptor (LDLR), which regulates the circulating cholesterol level. In this field, we discovered natural peptides derived from lupin that showed PCSK9 inhibitory activity. Among these, the most active peptide, known as P5 (LILPHKSDAD), reduced the protein-protein interaction between PCSK9 and LDLR with an IC₅₀ equals to 1.6 µM and showed a dual hypocholesterolemic activity, since it shows complementary inhibition of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR). (2) Methods: In this study, by a computational approach, the P5 primary structure was optimized to obtain new analogs with improved affinity to PCSK9. Then, biological assays were carried out for fully characterizing the dual cholesterol-lowering activity of the P5 analogs by using both biochemical and cellular techniques. (3) Results: A new peptide, P5-Best (LYLPKHSDRD) displayed improved PCSK9 (IC₅₀ 0.7 µM) and HMG-CoAR (IC₅₀ 88.9 µM) inhibitory activities. Moreover, in vitro biological assays on cells demonstrated that, not only P5-Best, but all tested peptides maintained the dual PCSK9/HMG-CoAR inhibitory activity and remarkably P5-Best exerted the strongest hypocholesterolemic effect. In fact, in the presence of this peptide, the ability of HepG2 cells to absorb extracellular LDL was improved by up to 254%. (4) Conclusions: the atomistic details of the P5-Best/PCSK9 and P5-Best/HMG-CoAR interactions represent a reliable starting point for the design of new promising molecular entities endowed with hypocholesterolemic activity.

Assessment of the Cholesterol-Lowering Effect of MOMAST®: Biochemical and Cellular Studies

MOMAST® is a patented phenolic complex derived from the olive oil vegetation water, a by-product of the olive oil supply chain, in which hydroxytyrosol (OH-Tyr) and tyrosol (Tyr) and verbascoside are the main compounds. This study was aimed at investigating its hypocholesterolemic effect by assessing the ability to modulate the low-density lipoprotein (LDL) receptor (LDLR)/sterol regulatory element-binding protein 2 (SREBP-2), and proprotein convertase subtilisin/kexin type 9 (PCSK9) pathways. MOMAST® inhibits the in vitro activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCOAR) with a dose-response trend. After the treatment of HepG2 cells, MOMAST® increases the SREBP-2, LDLR, and HMGCoAR protein levels leading, from a functional point of view to an improved ability of hepatic cells to up-take LDL from the extracellular environment with a final cholesterol-lowering effect. Furthermore, MOMAST® decreased the PCSK9 protein levels and its secretion in the extracellular environment, presumably via the reduction of the hepatic nuclear factor 1-α (HNF1-α). The experiments were performed in parallel, using pravastatin as a reference compound. Results demonstrated that MOMAST® may be exploited as a new ingredient for the development of functional foods and/or nutraceuticals for cardiovascular disease prevention.

Lupin-Derived Bioactive Peptides: Intestinal Transport, Bioavailability and Health Benefits

There is a renewed interest on the reliance of food-based bioactive compounds as sources of nutritive factors and health-beneficial chemical compounds. Among these food components, several proteins from foods have been shown to promote health and wellness as seen in proteins such as α/γ-conglutins from the seeds of Lupinus species (Lupin), a genus of leguminous plant that are widely used in traditional medicine for treating chronic diseases. Lupin-derived peptides (LDPs) are increasingly being explored and they have been shown to possess multifunctional health improving properties. This paper discusses the intestinal transport, bioavailability and biological activities of LDPs, focusing on molecular mechanisms of action as reported in in vitro, cell culture, animal and human studies. The potentials of several LDPs to demonstrate multitarget mechanism of regulation of glucose and lipid metabolism, chemo- and osteoprotective properties, and antioxidant and anti-inflammatory activities position LDPs as good candidates for nutraceutical development for the prevention and management of medical conditions whose etiology are multifactorial.

Legumes as Functional Food for Cardiovascular Disease

Legumes are an essential food source worldwide. Their high-quality proteins, complex carbohydrates, dietary fiber, and relatively low-fat content make these an important functional food. Known to possess a multitude of health benefits, legume consumption is associated with the prevention and treatment of cardiovascular diseases (CVD). Legume crude protein isolates and purified peptides possess many cardiopreventive properties. Here, we review selected economically valued legumes, their taxonomy and distribution, biochemical composition, and their protein components and the mechanism(s) of action associated with cardiovascular health. Most of the legume protein studies had shown upregulation of low-density lipoprotein (LDL) receptor leading to increased binding and uptake, in effect significantly reducing total lipid levels in the blood serum and liver. This is followed by decreased biosynthesis of cholesterol and fatty acids. To understand the relationship of identified genes from legume studies, we performed gene network analysis, pathway, and gene ontology (GO) enrichment. Results showed that the genes were functionally interrelated while enrichment and pathway analysis revealed involvement in lipid transport, fatty acid and triglyceride metabolic processes, and regulatory processes. This review is the first attempt to collate all known mechanisms of action of legume proteins associated with cardiovascular health. This also provides a snapshot of possible targets leading to systems-level approaches to further investigate the cardiometabolic potentials of legumes.

Safety and Efficacy of a Beverage Containing Lupine Protein Hydrolysates on the Immune, Oxidative and Lipid Status in Healthy Subjects: An Intervention Study (the Lupine-1 Trial)

SCOPE

We have previously demonstrated the anti-inflammatory and antioxidant properties of in vitro administered Lupinus angustifolius protein hydrolysates (LPHs) on human peripheral blood mononuclear cells (PBMCs). This study aims to evaluate the safety and efficacy of a beverage containing LPHs (LPHb) on the immune, oxidative and metabolic status of healthy subjects.

METHODS AND RESULTS

In this open-label intervention, 33 participants daily ingest a LPHb containing 1 g LPHs for 28 days. Biochemical parameters are assayed in fasting peripheral blood and urine samples before, during (14 days) and after LPHb ingestion. Participants' health status and the immune and antioxidant responses of PBMCs are also evaluated throughout the trial. The LPHb ingestion is safe and effective in both increasing the anti-/pro-inflammatory response of PBMCs and improving the cellular anti-oxidant capacity. LPHb also reduces the low-density lipoprotein-cholesterol (LDL-C)/high-density lipoprotein-cholesterol (HDL-C) atherogenic index. LPHb effect is particularly beneficial on decreasing not only the LDL-C/HDL-C index but also serum total cholesterol levels in the male cohort that shows the highest baseline levels of well-known cardiovascular risk factors.

CONCLUSION

This is the first study to show the pleiotropic actions of a lupine bioactive peptides-based functional food on key steps of atherosclerosis including inflammation, oxidative stress, and cholesterol metabolism.

Trans-Epithelial Transport, Metabolism, and Biological Activity Assessment of the Multi-Target Lupin Peptide LILPKHSDAD (P5) and Its Metabolite LPKHSDAD (P5-Met)

P5 (LILPKHSDAD) is a hypocholesterolemic peptide from lupin protein with a multi-target activity, since it inhibits both 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCoAR) and proprotein convertase subtilisin/kexin type-9 (PCSK9). This work shows that, during epithelial transport experiments, the metabolic transformation mediated by intestinal peptidases produces two main detected peptides, ILPKHSDAD (P5-frag) and LPKHSDAD (P5-met), and that both P5 and P5-met are linearly absorbed by differentiated human intestinal Caco-2 cells. Extensive comparative structural, biochemical, and cellular characterizations of P5-met and the parent peptide P5 demonstrate that both peptides have unique characteristics and share the same mechanisms of action. In fact, they exert an intrinsically multi-target behavior being able to regulate cholesterol metabolism by modulating different pathways. The results of this study also highlight the dynamic nature of bioactive peptides that may be modulated by the biological systems they get in contact with.

Butyric Acid Added Apically to Intestinal Caco-2 Cells Elevates Hepatic ApoA-I Transcription and Rescues Lower ApoA-I Expression in Inflamed HepG2 Cells Co-Cultured in the Basolateral Compartment

Apolipoprotein A-I (ApoA-I) concentrations are decreased during inflammation, which may reduce high-density lipoprotein (HDL) functionality. Thus, rescuing ApoA-I concentrations during inflammation might help to prevent atherosclerosis. Recent studies have shown that butyric acid (C4) has anti-inflammatory effects and rescues ApoA-I production. However, whether intestinal short chain fatty acids (SCFAs) are able to influence hepatic processes is unknown. Therefore, we investigated C4 anti-inflammatory effects on ApoA-I transcription in the intestine-liver co-culture model. C4 dose-response experiments in the presence or absence of cytokines were performed in a co-culture system including Caco-2 cells, HepG2 cells, or both. Changes in ApoA-I transcription in Caco-2 cells and HepG2 cells were analyzed using qPCR. C4 increased ApoA-I expression in HepG2 cells that cultured alone. When both cells were cultured together, C4 decreased ApoA-I expression in Caco-2 cells and increased ApoA-I expression in HepG2 cells. However, adding C4 to apical Caco-2 cells resulted in a smaller effect in HepG2 cells compared with adding C4 directly to the hepatocytes. Moreover, C4 rescued ApoA-I expression in inflamed HepG2 cells. These findings suggests that intestinal SCFAs can affect hepatic processes. However, the smaller effect in the co-culture experiment indicates cross-talk between intestine and liver.

Assessment of the Multifunctional Behavior of Lupin Peptide P7 and Its Metabolite Using an Integrated Strategy

LTFPGSAED (P7) is a multifunctional hypocholesterolemic and hypoglycemic lupin peptide. While assessing its angiotensin-converting enzyme (ACE) inhibitory activity, it was more effective in intestinal Caco-2 cells (IC₅₀ of 13.7 μM) than in renal HK-2 cells (IC₅₀ of 79.6 μM). This discrepancy was explained by the metabolic transformation mediated by intestinal peptidases, which produced two main detected peptides, TFPGSAED and LTFPG. Indeed LTFPG, dynamically generated by intestinal dipeptidyl peptidase IV as well as its parent peptide P7 were linearly absorbed by mature Caco-2 cells. An in silico study demonstrated that the metabolite was a better ligand of the ACE enzyme than P7. These results are in agreement with an in vivo study, previously performed by Aluko et al., which has shown that LTFPG is an effective hypotensive peptide. Our work highlights the dynamic nature of bioactive food peptides that may be modulated by the metabolic activity of intestinal cells.

Efficacy of a Novel ACE-Inhibitory Peptide from Sargassum Maclurei in Hypertension and Reduction of Intracellular Endothelin-1

Sargassum maclurei is a potential protein resource because of its high protein content and relatively balanced amino acid composition. To promote its usage in food, medical, or other industries, S. maclurei protein was hydrolyzed by pepsin and papain to obtain bioactive peptides. The S. maclurei protein hydrolysates (SMPHs) were purified using gel chromatography and reversed-phase high performance liquid chromatography (RP-HPLC), and 12 major fractions were obtained. The fraction D11 with the highest angiotensin I-converting enzyme (ACE) inhibition (61.59%, at 1 mg/ mL) was subjected to liquid chromatography-mass spectrometry (LC-MS/MS) analysis, and about 17 peptides were identified, of which the RWDISQPY (1063.5 Da) was chosen to be synthesized based on in silico analysis. The RWDISQPY demonstrated high ACE inhibition ability (IC50: 72.24 μM) with competitive inhibition mode, and could effectively (p < 0.05) lower the systolic blood pressure and diastolic pressure of spontaneously hypertensive rats at the concentration of 150 mg/kg body weight. The results of the molecular docking simulation demonstrated that RWDISQPY could bind with the active sites S1 and S2 of ACE via short hydrogen bonds. Moreover, RWDISQPY showed acceptable endothelin-1 suppressing capacity (26.21% at 1.5 mg/mL). These results indicate that S. maclurei could be developed into functional foods such as antihypertensive products.

Soybean Peptides Exert Multifunctional Bioactivity Modulating 3-Hydroxy-3-Methylglutaryl-CoA Reductase and Dipeptidyl Peptidase-IV Targets in Vitro

This study was aimed at evaluating the cellular mechanism through which peptic (P) and tryptic (T) soybean hydrolysates modulate the targets involved in hypocholesterolemic pathways in HepG2 and antidiabetic pathways in Caco-2 cells. Both hydrolysates (tested in the concentration range of 0.5-2.5 mg/mL) inhibited the 3-hydroxy-3-methylglutaryl-CoA reductase activity in HepG2 cells. In addition, Soybean P increased LDLR protein levels on HepG2 membranes by 51.5 ± 11.6% and 63.0 ± 6.9% (0.5-1.0 mg/mL) whereas Soybean T increased them by 55.2 ± 9.7% and 85.8 ± 21.5% (0.5-1.0 mg/mL) vs the control, with a final improved HepG2 capacity in the uptake of extracellular LDL. Soybean P reduced in vitro the dipeptidyl peptidase-IV activity by 16.3 ± 3.0% and 31.4 ± 0.12% (1.0 and 2.5 mg/mL), whereas Soybean T reduced it by 15.3 ± 11.0% and 11.0 ± 0.30% (1.0 and 2.5 mg/mL) vs the control. Finally, both hydrolysates inhibited dipeptidyl peptidase-IV activity in situ in human intestinal Caco-2 cells. This investigation may help to explain the activities observed in experimental and clinical studies.

Identification and characterization of a novel casein anticoagulant peptide derived from in vivo digestion

A novel anticoagulant casein peptide has been identified by in vivo digestion.

Isolation and identification by high resolution liquid chromatography tandem mass spectrometry of novel peptides with multifunctional lipid-lowering capacity

This work describes the isolation, characterization, and identification by RP-HPLC-ESI-Q-TOF of novel peptides that interfere in the fat digestion and absorption mechanisms by multiple pathways. Peptides were ultrafiltrated and peptides in the most active fraction were further separated by semipreparative RP-HPLC. Nine different subfractions were obtained observing a high amount of peptides in subfraction F3. Peptides in subfraction F3 could simultaneously reduce the solubility of cholesterol in micelles and inhibit pancreatic cholesterol esterase and pancreatic lipase, even after a simulated gastrointestinal digestion. The identification of lipid-lowering peptides has been scarcely performed and when done, low selectivity or sensitivity of employed identification techniques or conditions did not yield reliable results. Separation and detection of peptides by RP-HPLC-ESI-Q-TOF-MS was optimized and most favorable conditions were employed for the identification of peptides using de novo sequencing. Ten different peptides with 4-9 amino acids were identified. Main feature of identified peptides was the high acidity derived from a high presence of amino acids glutamic acid and aspartic acid in their sequences.

Bioactivities of alternative protein sources and their potential health benefits

Increasing the utilisation of plant proteins is needed to support the production of protein-rich foods that could replace animal proteins in the human diet so as to reduce the strain that intensive animal husbandry poses to the environment.

Peptides Derived from Soy and Lupin Protein as Dipeptidyl-Peptidase IV Inhibitors: In Vitro Biochemical Screening and in Silico Molecular Modeling Study

Dipeptidyl peptidase IV (DPP-IV) is a new molecular target correlated with the development of type 2 diabetes. Literature describes the identification of some inhibitory peptides from the hydrolysis of different food proteins. This article reports a study on six peptides from soybean and lupin proteins, i.e., Soy 1 (IAVPTGVA), Soy 2 (YVVNPDNDEN), Soy 3 (YVVNPDNNEN), Lup 1 (LTFPGSAED), Lup 2 (LILPKHSDAD), and Lup 3 (GQEQSHQDEGVIVR), which were screened for their capacity to inhibit the activity of DPP-IV, using an in vitro bioassay against human recombinant DPP-IV. Two peptides Soy 1 and Lup 1 resulted to be efficient inhibitors with IC50 values equal to 106 and 228 μM, respectively. A molecular docking analysis predicted the key molecular interactions, stabilizing the active peptides within DPP-IV enzyme. Soy and lupin proteins may be sources of DPP-IV inhibitory peptides potentially useful for the prevention of type 2 diabetes.