Olive (Olea europaea L.) Seed as New Source of Cholesterol-Lowering Bioactive Peptides: Elucidation of Their Mechanism of Action in HepG2 Cells and Their Trans-Epithelial Transport in Differentiated Caco-2 Cells

The production of olive oil has important economic repercussions in Mediterranean countries but also a considerable impact on the environment. This production generates enormous quantities of waste and by-products, which can be exploited as new raw materials to obtain innovative ingredients and therefore make the olive production more sustainable. In a previous study, we decided to foster olive seeds by generating two protein hydrolysates using food-grade enzymes, alcalase (AH) and papain (PH). These hydrolysates have shown, both in vitro and at the cellular level, antioxidant and antidiabetic activities, being able to inhibit the activity of the DPP-IV enzyme and modulate the secretion of GLP-1. Given the multifunctional behavior of peptides, both hydrolysates displayed dual hypocholesterolemic activity, inhibiting the activity of HMGCoAR and impairing the PPI of PCSK9/LDLR, with an IC50 equal to 0.61 mg/mL and 0.31 mg/mL for AH and PH, respectively. Furthermore, both samples restored LDLR protein levels on the membrane of human hepatic HepG2 cells, increasing the uptake of LDL from the extracellular environment. Since intestinal bioavailability is a key component of bioactive peptides, the second objective of this work is to evaluate the capacity of AH and PH peptides to be transported by differentiated human intestinal Caco-2 cells. The peptides transported by intestinal cells have been analyzed using mass spectrometry analysis, identifying a mixture of stable peptides that may represent new ingredients with multifunctional qualities for the development of nutraceuticals and functional foods to delay the onset of metabolic syndrome, promoting the principles of environmental sustainability.

Glycomacropeptide (GMP) rescued the oxidative and inflammatory activity of free L-AAs in human Caco-2 cells: New insights that support GMP as a valid and health-promoting product for the dietary management of phenylketonuria (PKU) patients

Phenylketonuria represents the most prevalent inborn error of amino acid metabolism. In early diagnosed patients adequate and continued dietary treatment results in a good neurologic outcome. However, due to the natural protein and phenylalanine-restricted diet, oxidative stress represents a concern in phenylketonuric patients. Clear evidences suggest that the pathophysiology of PKU is also dependent by mitochondrial impairment and oxidative stress. In this context due to the tight connection between oxidative and inflammatory stress and noncommunicable diseases (NCDs) development, it is reasonable to hypothesize that PKU patients may present a higher risk to develop NCDs during their life. Currently available protein substitutes on the market include free amino acids (L-AAs), prolonged-release protein substitute and formula containing glycomacropeptide (GMP). Our results suggest that free L-AAs significanlty worsens the intestinal hydrogen peroxide (H2O2) and lipopolysaccharides (LPS)-induced oxidative and inflammatory status in Caco-2 cells, which are significantly restored towards physiological condition by GMP alone and when present in a 1:1 mixture with free L-AAs, providing new preclinical piece of information which can shed a shadow on the mechanism of action of these products on PKU patients and their future management.

Bioavailability Assessment of an Iron Formulation Using Differentiated Human Intestinal Caco-2 Cells

In recent years, there has been growing interest in exploring alternative and innovative delivery systems to improve the efficacy of iron supplements, satisfying iron needs and lowering side effects. To address this issue, this study aimed at demonstrating the advantages of Ferro Supremo formulation (composed of encapsulated iron, vitamins, and micronutrients), in terms of capacity to improve iron intestinal absorption, in comparison with standard FeSO4. Hence, differentiated Caco-2 cells have been used for assessing the in vitro bioavailability and safety of FS and FeSO4. MTT experiments demonstrated that both FS and FeSO4 are not able to impair the viability of Caco-2 cells. Furthermore, the quantitative and qualitative analysis, conducted by atomic absorption spectrometry and fluorescence determinations, revealed that FS can enter, accumulate in the cytoplasm, and be transported by intestinal cells four times more efficiently than FeSO4. Our findings indicate that this formulation can be considered a valuable and efficiently good choice as food supplements for improving iron deficiency.

MOMAST® Reduces the Plasmatic Lipid Profile and Oxidative Stress and Regulates Cholesterol Metabolism in a Hypercholesterolemic Mouse Model: The Proof of Concept of a Sustainable and Innovative Antioxidant and Hypocholesterolemic Ingredient

MOMAST^® is a patented natural phenolic complex, rich in tyrosol (9.0 g/kg, Tyr), hydroxityrosol (43,5 g/kg, OH-Tyr), and verbascoside (5.0 g/Kg), which is obtained from the OVW by-product of the Coratina cultivar with potent direct antioxidant activity (measured by DPPH and FRAP assays, respectively). Indeed, MOMAST^® represents an innovative sustainable bioactive ingredient which has been obtained with ethical and empowering behavior by applying the principles of a circular economy. In the framework of research aimed at fostering its health-promoting activity, in this study it was clearly demonstrated that MOMAST^® treatment reduced the oxidative stress and levels of total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol, and increased the HDL levels, without changes in the triglyceride (TG) levels in Western diet (WD)-fed mice. The modulation of the plasmatic lipid profile is similar to red yeast rice (RYR) containing Monacolin K (3%). In addition, at the molecular level in liver homogenates, similarly to RYR, MOMAST^® exerts cholesterol-lowering activity through the activation of LDL receptor, whereas, unlike RYR, MOMAST^® reduces proprotein convertase subtilisin/kexin type 9 (PCSK9) protein levels via hepatic nuclear factor 1 (HNF1)-α activation. Hence, this study provides the proof of concept regarding the hypocholesterolemic activity of MOMAST, which could be successfully exploited as an active ingredient for the development of innovative and sustainable dietary supplements and functional foods.

Computational Mechanics of Form-Fitting 3D-Printed Lattice-Based Wrist-Hand Orthosis for Motor Neuron Disease

Motor neuron disease (MND) patients often experience hand-wrist muscle atrophy resulting in severe social consequences and hampering their daily activities. Although hand-wrist orthosis is commonly used to assist weakened muscles, its effectiveness is limited due to the rapid progression of the disease and the need for customization to suit individual patient requirements. To address these challenges, this study investigates the application of three-dimensional (3D) printing technology to design and fabricate two lattice structures inspired by silkworm cocoons, using poly-ε-caprolactone as feedstock material. Finite element method (FEM) analysis is employed to study the mechanical behavior, enabling control over the geometric configuration incorporated into the hand-wrist orthosis. Through tensile displacement and three-point bending simulations, the stress distribution is examined for both lattice geometries. Geometry-1 demonstrates anisotropic behavior, while geometry-2 exhibits no strict directional dependence due to its symmetry and uniform node positioning. Moreover, the biocompatibility of lattices with human skin fibroblasts is investigated, confirming excellent biocompatibility. Lastly, the study involves semi-structured interviews with MND patients to gather feedback and develop prototypes of form-fitting 3D-printed lattice-based hand-wrist orthosis. By utilizing 3D printing technology, this study aims to provide customized orthosis that can effectively support weakened muscles and reposition the hand for individuals with MND.

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.

Antioxidant Effect Assessment and Trans Epithelial Analysis of New Hempseed Protein Hydrolysates

Hempseed (Cannabis sativa) is one of the most promising sources of plant proteins. It contains approximately 24% (w/w) protein, and edestin accounts for approximately 60-80% (w/w) of its total proteins. In a framework of research aimed at fostering the proteins recovered from the press cake by-products generated after the extraction of hempseed oil, two hempseed protein hydrolysates (HH1 and HH2) were produced at an industrial level using a mixture of different enzymes from Aspergillus niger, Aspergillus oryzae, and Bacillus licheniformis for different times (5 h and 18 h). Using a combination of different direct antioxidant tests (DPPH, TEAC, FRAP, and ORAC assays, respectively), it has been demonstrated that HHs exert potent, direct antioxidant activity. A crucial feature of bioactive peptides is their intestinal bioavailability; for this reason, in order to solve this peculiar issue, the ability of HH peptides to be transported by differentiated human intestinal Caco-2 cells has been evaluated. Notably, by using mass spectrometry analysis (HPLC Chip ESI-MS/MS), the stable peptides transported by intestinal cells have been identified, and dedicated experiments confirmed that the trans-epithelial transported HH peptide mixtures retain their antioxidant activity, suggesting that these hempseed hydrolysates may be considered sustainable antioxidant ingredients to be exploited for further application, i.e., nutraceutical and/or food industries.

Valorization of the Antioxidant Effect of Mantua PGI Pear By-Product Extracts: Preparation, Analysis and Biological Investigation

For improving the management of the production chain of PGI Mantua pears (which comprises many varieties, including Abate Fetel), applying the cardinal principles of circular economy and sustainability, the fruits with diseases or defects were recovered for producing dried rounds of pears from the Abate Fetel cultivar, a new product with high nutritional value that extends the remaining life. This process led to the production of secondary and residual by-products, which are mainly composed of the highest and lowest part of the fruits, comprising seeds, pulps, peels and petioles. Hence, this study was focused on the valorization of these secondary by-products of Abate Fetel pears through the production of pear extracts using traditional and "green" extraction methods that involve the use of supercritical CO₂ fluid extraction. The produced extracts, together with a reference solvent-derived extract, were analyzed by HPLC-ESI-MS, and in parallel, their direct and cellular antioxidant activity were assessed. Evidence has indicated that all the tested extracts reduced the H₂O₂-induced reactive oxygen species (ROS), lipid peroxidation and nitric oxide (NO) levels, respectively, in human intestinal Caco-2 cells. Hence, this study clearly suggests that extracts obtained from Mantuan PGI pear by-products may be used as valuable sources of bioactive upcycled phytocomplex for the development of dietary supplements and/or functional foods.

Isolation and functional characterization of hemp seed protein-derived short- and medium-chain peptide mixtures with multifunctional properties for metabolic syndrome prevention

This study aims to obtain a valuable mixture of short-chain peptides from hempseed as a new ingredient for developing nutraceutical and functional foods useful for preventing metabolic syndrome that represents the major cause of death globally. A dedicated analytical platform based on a purification step by size exclusion chromatography or ultrafiltration membrane and high-resolution mass spectrometry was developed to isolate and comprehensively characterize short-chain peptides leading to the identification of more than 500 short-chain peptides. Our results indicated that the short-chain peptide mixture was about three times more active than the medium-chain peptide mixture and total hydrolysate with respect to measured inhibition of the angiotensin-converting enzyme. The short-chain peptide mixture was also two times more active as a dipeptidyl peptidase IV, and twofold more active on the cholesterol metabolism pathway through the modulation of low-density lipoprotein receptor.

Discovery of a Potent and Highly Selective Dipeptidyl Peptidase IV and Carbonic Anhydrase Inhibitor as "Antidiabesity" Agents Based on Repurposing and Morphing of WB-4101

The management of patients with type 2 diabetes mellitus (T2DM) is shifting from cardio-centric to weight-centric or, even better, adipose-centric treatments. Considering the downsides of multidrug therapies and the relevance of dipeptidyl peptidase IV (DPP IV) and carbonic anhydrases (CAs II and V) in T2DM and in the weight loss, we report a new class of multitarget ligands targeting the mentioned enzymes. We started from the known α₁-AR inhibitor WB-4101, which was progressively modified through a tailored morphing strategy to optimize the potency of DPP IV and CAs while losing the adrenergic activity. The obtained compound 12 shows a satisfactory DPP IV inhibition with a good selectivity CA profile (DPP IV IC₅₀: 0.0490 μM; CA II K_i 0.2615 μM; CA VA K_i 0.0941 μM; CA VB K_i 0.0428 μM). Furthermore, its DPP IV inhibitory activity in Caco-2 and its acceptable pre-ADME/Tox profile indicate it as a lead compound in this novel class of multitarget ligands.

Exploitation of Olive (Olea europaea L.) Seed Proteins as Upgraded Source of Bioactive Peptides with Multifunctional Properties: Focus on Antioxidant and Dipeptidyl-Dipeptidase—IV Inhibitory Activities, and Glucagon-like Peptide 1 Improved Modulation

Agri-food industry wastes and by-products include highly valuable components that can upgraded, providing low-cost bioactives or used as an alternative protein source. In this context, by-products from olive production and olive oil extraction process, i.e., seeds, can be fostered. In particular, this work was aimed at extracting and characterizing proteins for Olea europaea L. seeds and at producing two protein hydrolysates using alcalase and papain, respectively. Peptidomic analysis were performed, allowing to determine both medium- and short-sized peptides and to identify their potential biological activities. Moreover, an extensive characterization of the antioxidant properties of Olea europaea L. seed hydrolysates was carried out both in vitro by 2,2-diphenyl-1-picrylhydrazyl (DPPH), by ferric reducing antioxidant power (FRAP), and by 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays, respectively, and at cellular level by measuring the ability of these hydrolysates to significant reduce the H₂O₂-induced reactive oxygen species (ROS) and lipid peroxidation levels in human intestinal Caco-2 cells. The results of the both hydrolysates showed significant antioxidant properties by reducing the free radical scavenging activities up to 65.0 ± 0.1% for the sample hydrolyzed with alcalase and up to 75.7 ± 0.4% for the papain hydrolysates tested at 5 mg/mL, respectively. Moreover, similar values were obtained by the ABTS assays, whereas the FRAP increased up to 13,025.0 ± 241.5% for the alcalase hydrolysates and up to 12,462.5 ± 311.9% for the papain hydrolysates, both tested at 1 mg/mL. According to the in vitro results, both papain and alcalase hydrolysates restore the cellular ROS levels up 130.4 ± 4.24% and 128.5 ± 3.60%, respectively, at 0.1 mg/mL and reduce the lipid peroxidation levels up to 109.2 ± 7.95% and 73.0 ± 7.64%, respectively, at 1.0 mg/mL. In addition, results underlined that the same hydrolysates reduced the activity of dipeptidyl peptidase-IV (DPP-IV) in vitro and at cellular levels up to 42.9 ± 6.5% and 38.7 ± 7.2% at 5.0 mg/mL for alcalase and papain hydrolysates, respectively. Interestingly, they stimulate the release and stability of glucagon-like peptide 1 (GLP-1) hormone through an increase of its levels up to 660.7 ± 21.9 pM and 613.4 ± 39.1 pM for alcalase and papain hydrolysates, respectively. Based on these results, olive seed hydrolysates may represent new ingredients with antioxidant and anti-diabetic properties for the development of nutraceuticals and functional foods for the prevention of metabolic syndrome onset.

A Review on the Molecular Mechanisms of Action of Natural Products in Preventing Bone Diseases

The drugs used for treating bone diseases (BDs), at present, elicit hazardous side effects that include certain types of cancers and strokes, hence the ongoing quest for the discovery of alternatives with little or no side effects. Natural products (NPs), mainly of plant origin, have shown compelling promise in the treatments of BDs, with little or no side effects. However, the paucity in knowledge of the mechanisms behind their activities on bone remodeling has remained a hindrance to NPs’ adoption. This review discusses the pathological development of some BDs, the NP-targeted components, and the actions exerted on bone remodeling signaling pathways (e.g., Receptor Activator of Nuclear Factor κ B-ligand (RANKL)/monocyte/macrophage colony-stimulating factor (M-CSF)/osteoprotegerin (OPG), mitogen-activated protein kinase (MAPK)s/c-Jun N-terminal kinase (JNK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Kelch-like ECH-associated protein 1 (Keap-1)/nuclear factor erythroid 2–related factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1), Bone Morphogenetic Protein 2 (BMP2)-Wnt/β-catenin, PhosphatidylInositol 3-Kinase (PI3K)/protein kinase B (Akt)/Glycogen Synthase Kinase 3 Beta (GSK3β), and other signaling pathways). Although majority of the studies on the osteoprotective properties of NPs against BDs were conducted ex vivo and mostly on animals, the use of NPs for treating human BDs and the prospects for future development remain promising.

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.

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.

Investigation of the intestinal trans-epithelial transport and antioxidant activity of two hempseed peptides WVSPLAGRT (H2) and IGFLIIWV (H3)

A preceding paper has shown that a hempseed peptic hydrolysate displays a cholesterol-lowering activity with a statin-like mechanism of action in HepG2 cells and a potential hypoglycemic activity by the inhibition of dipeptidyl peptidase-IV in Caco-2 cells. In the framework of a research aimed at fostering the multifunctional behavior of hempseed peptides, we present here the identification and evaluation of some antioxidant peptides from the same hydrolysate. After evaluation of its diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, a trans-epithelial transport experiment was performed using differentiated Caco-2 cells that permitted the identification of five transported peptides that were synthesized and evaluated by measuring the oxygen radical absorbance capacity (ORAC), the ferric reducing antioxidant power (FRAP), and the 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), and diphenyl-2-picrylhydrazyl radical DPPH assays. The most active peptides, i.e. WVSPLAGRT (H2) and IGFLIIWV (H3), were then tested in cell assays. Both peptides were able to reduce the H₂O₂-induced reactive oxygen species (ROS), lipid peroxidation, and nitric oxide (NO) production levels in HepG2 cells, via the modulation of Nrf-2 and iNOS pathways, respectively.

Gel-Forming of Self-Assembling Peptides Functionalized with Food Bioactive Motifs Modulate DPP-IV and ACE Inhibitory Activity in Human Intestinal Caco-2 Cells

Food bioactive peptides are increasingly used for formulating food products, nutraceuticals, and functional food, since they are generally considered safe for human consumption and metabolic syndrome prevention. They are also becoming popular as sustainable sources of novel functional biomaterials such as hydrogels, edible nanonutraceuticals, delivery systems, and packing materials. However, such food peptides are mostly unstable, and degrade during food processing, or in a gastrointestinal environment, thus resulting in low bioavailability precluding their practical applications. Here, we decided to functionalize the well-known and characterized self-assembling peptide RADA16 with two synthetic analogues of food bioactive peptides deriving from the hydrolysis of soybean glycinin and lupin β-conglutin (namely IAVPTGVA and LTFPGSAED) for control of and improvement in their gel-forming nanostructures, biomechanics, and biological features. Extensive characterization was performed via Circular Dichroism (CD) spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR), Thioflavin T (ThT) binding assay, rheological measurements, and Atomic Force Microscopy (AFM) analysis. Lastly, since self-assembling peptides (SAPs) can be co-assembled with diluent SAPs (without a bioactive epitope) as an approach to control the density of biological signals and therefore attain enhanced bioactivity, we investigated the effect of the co-assembly of RADA16 and functionalized food bioactive SAPs (dubbed cAP-Soy1 and cAP-Lup1) for the growth of Caco-2 human intestinal cells and contextually we characterized their biological activities as DPP-IV and ACE inhibitors, in order to demonstrate their potential use for the prevention of metabolic syndrome.

Hempseed (Cannabis sativa) Peptides WVSPLAGRT and IGFLIIWV Exert Anti-inflammatory Activity in the LPS-Stimulated Human Hepatic Cell Line

WVSPLAGRT (H2) and IGFLIIWV (H3) are two transepithelial transported intestinal peptides obtained from the hydrolysis of hempseed protein with pepsin, which exert antioxidant activity in HepG2 cells. Notably, both peptides reduce the H2O2-induced reactive oxygen species, lipid peroxidation, and nitric oxide (NO) production levels in HepG2 cells via the modulation of the nuclear factor erythroid 2-related factor 2 and the inducible nitric oxide synthase (iNOS) pathways, respectively. Due to the close link between inflammation and oxidative stress and with the objective of fostering the multifunctional behavior of bioactive peptides, in this study, the molecular characterization of the anti-inflammatory and immunomodulatory properties of H2 and H3 was carried out in HepG2 cells. In fact, both peptides were shown to modulate the production of pro (IFN-γ: -33.0 ± 6.7% H2, p = 0.011; -13.1 ± 2.0% H3, p = <0.0001; TNF: -17.6 ± 1.7% H2, p = 0.0004; -20.3 ± 1.7% H3, p = <0.0001; and IL-6: -15.1 ± 6.5% H3, p = 0.010)- and anti (IL-10: +9.6 ± 3.1% H2, p = 0.010; +26.0 ± 2.3% H3, p = < 0.0001)-inflammatory cytokines and NO (-9.0 ± 0.7% H2, p = <0.0001; -7.2 ± 1.8% H3, p = <0.0001) through regulation of the NF-κB and iNOS pathways, respectively, in HepG2 cells stimulated by lipopolysaccharides.

A heuristic, computer-driven and top-down approach to identify novel bioactive peptides: A proof-of-principle on angiotensin I converting enzyme inhibitory peptides

Bioactive peptides are short peptides (3-20 amino acid residues in length) endowed of specific biological activities. The identification and characterization of bioactive peptides of food origin are crucial to better understand the physiological consequences of food, as well as to design novel foods, ingredients, supplements, and diets to counteract mild metabolic disorders. For this reason, the identification of bioactive peptides is also relevant from a pharmaceutical standpoint. Nevertheless, the systematic identification of bioactive sequences of food origin is still challenging and relies mainly on the so defined "bottom-up" approaches, which rarely results in the total identification of most active sequences. Conversely, "top-down" approaches aim at identifying bioactive sequences with certain features and may be more suitable for the precise identification of very potent bioactive peptides. In this context, this work presents a top-down, computer-assisted and hypothesis-driven identification of potent angiotensin I converting enzyme inhibitory tripeptides, as a proof of principle. A virtual library of 6840 tripeptides was screened in silico to identify potential highly potent inhibitory peptides. Then, computational results were confirmed experimentally and a very potent novel sequence, LMP was identified. LMP showed an IC₅₀ of 15.8 and 6.8 µM in cell-free and cell-based assays, respectively. In addition, a bioinformatics approach was used to search potential food sources of LMP. Yolk proteins were identified as a possible relevant source to analyze in further experiments. Overall, the method presented may represent a powerful and versatile framework for a systematic, high-throughput and top-down identification of bioactive peptides.

Phenolic Extracts from Extra Virgin Olive Oils Inhibit Dipeptidyl Peptidase IV Activity: In Vitro, Cellular, and In Silico Molecular Modeling Investigations

Two extra virgin olive oil (EVOO) phenolic extracts (BUO and OMN) modulate DPP-IV activity. The in vitro DPP-IV activity assay was performed at the concentrations of 1, 10, 100, 500, and 1000 μg/mL, showing a dose-dependent inhibition by 6.8 ± 1.9, 17.4 ± 6.1, 37.9 ± 2.4, 57.8 ± 2.9, and 81 ± 1.4% for BUO and by 5.4 ± 1.7, 8.9 ± 0.4, 28.4 ± 7.2, 52 ± 1.3, and 77.5 ± 3.5% for OMN. Moreover, both BUO and OMN reduced the DPP-IV activity expressed by Caco-2 cells by 2.9 ± 0.7, 44.4 ± 0.7, 61.2 ± 1.8, and 85 ± 4.2% and by 3 ± 1.9, 35 ± 9.4, 60 ± 7.2, and 82 ± 2.8%, respectively, at the same doses. The concentration of the most abundant and representative secoiridoids within both extracts was analyzed by nuclear magnetic resonance (¹H-NMR). Oleuropein, oleacein, oleocanthal, hydroxytyrosol, and tyrosol, tested alone, reduced the DPP-IV activity, with IC₅₀ of 472.3 ± 21.7, 187 ± 11.4, 354.5 ± 12.7, 741.6 ± 35.7, and 1112 ± 55.6 µM, respectively. Finally, in silico molecular docking simulations permitted the study of the binding mode of these compounds.

Increased Valency Improves Inhibitory Activity of Peptides Targeting Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9)

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a clinically validated target for treating hypercholesterolemia. Peptide-based PCSK9 inhibitors have attracted pharmaceutical interest, but the effect of multivalency on bioactivity is poorly understood. Here we designed bivalent and tetravalent dendrimers, decorated with the PCSK9 inhibitory peptides Pep2-8[RRG] or P9-38, to study relationships between peptide binding affinity, peptide valency, and PCSK9 inhibition. Increased valency resulted in improved PCSK9 inhibition for both peptides, with activity improvements of up to 100-fold achieved for the P9-38-decorated dendrimers compared to monomeric P9-38 in in vitro competition binding assays. Furthermore, the P9-38-decorated dendrimers showed improved potency at restoring functional low-density lipoprotein (LDL) receptor levels and internalizing LDL in the presence of PCSK9, demonstrating significant cell-based activity at picomolar concentrations. This study demonstrates the potential of increasing valency as a strategy for increasing the efficacy of peptide-based PCSK9 therapeutics.

Assessment of the Physicochemical and Conformational Changes of Ultrasound-Driven Proteins Extracted from Soybean Okara Byproduct

This study was aimed at the valorization of the okara byproduct deriving form soy food manufacturing, by using ultrasound at different temperatures for extracting the residual proteins. The physicochemical and conformational changes of the extracted proteins were investigated in order to optimize the procedure. Increasing the temperature from 20 up to 80 °C greatly enhanced the yields and the protein solubility without affecting the viscosity. The protein secondary and tertiary structures were also gradually modified in a significant way. After the ultrasonication at the highest temperature, a significant morphological transition from well-defined single round structures to highly aggregated ones was observed, which was confirmed by measuring the water contact angles and wettability. After the ultrasound process, the improvement of peptides generation and the different amino acid exposition within the protein led to an increase of the antioxidant properties. The integrated strategy applied in this study allows to foster the okara protein obtained after ultrasound extraction as valuable materials for new applications.

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.

Virgin Olive Oil Extracts Reduce Oxidative Stress and Modulate Cholesterol Metabolism: Comparison between Oils Obtained with Traditional and Innovative Processes

This study was aimed at demonstrating the substantial equivalence of two extra virgin olive oil samples extracted from the same batch of Coratina olives with (OMU) or without (OMN) using ultrasound technology, by performing chemical, biochemical, and cellular investigations. The volatile organic compounds compositions and phenolic profiles were very similar, showing that, while increasing the extraction yields, the innovative process does not change these features. The antioxidant and hypocholesterolemic activities of the extra virgin olive oil (EVOO) phenol extracts were also preserved, since OMU and OMN had equivalent abilities to scavenge the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicals in vitro and to protect HepG2 cells from oxidative stress induced by H₂O₂, reducing intracellular reactive oxygen species (ROS) and lipid peroxidation levels. In addition, by inhibiting 3-hydroxy-3-methylglutarylcoenzyme a reductase, both samples modulated the low-density lipoprotein receptor (LDLR) pathway leading to increased LDLR protein levels and activity.

Phycobiliproteins from Arthrospira Platensis (Spirulina): A New Source of Peptides with Dipeptidyl Peptidase-IV Inhibitory Activity

Arthrospira platensis (spirulina) is a cyanobacterium, which contains mainly two phycobiliproteins (PBP), i.e., C-phycocyanin (C-PC) and allophycocyanin (APC). In this study, PBP were hydrolyzed using trypsin, and the composition of the hydrolysate was characterized by HPLC-ESI-MS/MS. Furthermore, the potential anti-diabetic activity was assessed by using either biochemical or cellular techniques. Findings suggest that PBP peptides inhibit DPP-IV activity in vitro with a dose-response trend and an IC₅₀ value falling in the range between 0.5 and 1.0 mg/mL. A lower inhibition of the DPP-IV activity expressed by Caco-2 cells was observed, which was explained by a secondary metabolic degradation exerted by the same cells.

"Bottom-Up" Strategy for the Identification of Novel Soybean Peptides with Angiotensin-Converting Enzyme Inhibitory Activity

IAVPTGVA (Soy1) and LPYP are two soybean peptides, which display a multifunctional behavior, showing in vitro hypocholesterolemic and hypoglycemic activities. A preliminary screening of their structures using BIOPEP suggested that they might be potential angiotensin-converting enzyme (ACE) inhibitors. Therefore, a bottom-up-aided approach was developed in order to clarify the in vitro hypotensive activity. Soy1 and LPYP dropped the intestinal and renal ACE enzyme activity with IC50 values equal to 14.7 ± 0.28 and 5.0 ± 0.28 μM (Caco-2 cells), and 6.0 ± 0.35 and 6.8 ± 0.20 μM (HK-2 cells), respectively. In parallel, a molecular modeling study suggested their capability to act as competitive inhibitors of this enzyme. Finally, in order to increase both their stability and hypotensive properties, a suitable strategy for the harmless control of their release from a nanomaterial was developed through their encapsulation into the RADA16-assembling peptide.

Lupin Peptide T9 (GQEQSHQDEGVIVR) Modulates the Mutant PCSK9D374Y Pathway: in vitro Characterization of its Dual Hypocholesterolemic Behavior

GQEQSHQDEGVIVR (T9) is a peptide originated by the tryptic digestion of lupin β-conglutin that is absorbed in human intestinal Caco-2 cells. A previous study has shown that T9 impairs the protein–protein interaction between mutant D374Y Proprotein Convertase Subtilisin/Kexin 9 (PCSK9^D374Y) and the low-density lipoprotein receptor (LDLR), thus exerting a hypocholesterolemic effect. Moreover, a bioinformatic study predicting that T9 may potentially act as an inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCoAR), has suggested a complementary cholesterol-lowering activity. The present study demonstrates that T9 inhibits in vitro the HMGCoAR functionality with an IC₅₀ value of 99.5 ± 0.56 µM. Through the inhibition of either HMGCoAR or PCSK9^D374Y activities, T9 enhances the LDLR protein levels leading to an improved ability of HepG2 cells transfected with the mutant PCSK9^D374Y-FLAG plasmid to uptake extracellular LDL with a final cholesterol-lowering effect. In addition, T9 modulates the PCSK9^D374Y signaling pathway in transfected HepG2 cells leading to a decrease of PCSK9^D374Y and HNF-1α protein levels. All these results indicate that the hypocholesterolemic effects of T9 are due to a dual mechanism of action involving either the modulation of the PCSK9^D374Y or LDLR pathways. This may represent an added value from a therapeutic point of view.

A Supramolecular Approach to Develop New Soybean and Lupin Peptide Nanogels with Enhanced Dipeptidyl Peptidase IV (DPP-IV) Inhibitory Activity

Soy1 (IAVPTGVA) and Lup1 (LTFPGSAED), two peptides from soybean and lupin protein hydrolysis, have been singled out as dipeptidyl peptidase IV (DPP-IV) activity inhibitors in different model systems. However, their activity is affected by their instability toward intestinal proteases. Here, an innovative strategy based on nanogels was developed in order to increase both their stability and antidiabetic properties through encapsulation into the RADA16 peptide. The nanogel formation was stimulated by a solvent-triggered approach, allowing us to produce stable nanogels ( G' = 1826 Pa, stress-failure ≥50 Pa) with shear-thinning propensity. ThT binding assay, and ATR-FTIR spectroscopy experiments showed that nanogels self-aggregated into stable cross-β structures providing higher resistance against proteases (ex vivo experiments) and increased bioavailability of Soy1 and Lup1 peptides (in situ experiments on Caco-2 cells). Hence, this simple and harmless nanotechnological approach could be a key-step in making innovative nanomaterials for nutraceuticals delivering.

Enhancement of the Stability and Anti-DPPIV Activity of Hempseed Hydrolysates Through Self-Assembling Peptide-Based Hydrogels

Although there is an increasing interest for bioactive food protein hydrolysates as valuable ingredients for functional food and dietary supplement formulations, their potential applications are hampered by their insufficient stability in physiological conditions. In this study, an innovative strategy based on nanomaterials was developed in order to increase the hempseed hydrolysate stability and the anti-diabetic properties, through their encapsulation into ionic self-complementary RADA16 peptide based-hydrogels. Atomic force microscope (AFM) morphological analysis indicated that the new nanomaterials were composed of a nanofibril network, whose increased diameter in respect to native RADA16 suggests the presence of transient non-covalent interactions among the RADA16 supramolecular assemblies and the embedded hempseed peptides. Structural analysis by FT-IR spectroscopy indicated typical β-sheet signatures. The RADA16-hempseed protein hydrolysate hydrogel was shown to act as a novel dipeptidyl peptidase IV (DPPIV) inhibitor in different biological assays. Finally, this nanoformulation was used as a drug delivery system of the anti-diabetic drug sitagliptin, helping to reduce its dosage and eventually associated side-effects.

First Food-Derived Peptide Inhibitor of the Protein-Protein Interaction between Gain-of-Function PCSK9D374Y and the Low-Density Lipoprotein Receptor

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is involved in cholesterol homeostasis, because it induces the low-density lipoprotein receptor (LDLR) degradation. This protein may carry some positive or negative mutations: PCSK9^D374Y is one of the most dangerous gain-of-function mutations. This paper reports the identification of the first food-derived peptide able to inhibit the protein-protein interaction (PPI) between PCSK9^D374Y and LDLR. In fact, T9 (GQEQSHQDEGVIVR), an absorbable peptide deriving from lupin β-conglutin, is able to impair the PPI between PCSK9^D374Y and the LDLR, with an IC₅₀ value equal to 285.6 ± 2.46 μM. The consequence of this inhibition is an increase of the protein level of the LDLR located on hepatic cell membranes up to 74.3 ± 4.4% and the restoration of the functional capability of HepG2 cells to uptake extracellular low-density lipoprotein up to 83.1 ± 1.6%. Finally, the putative binding mode of T9 to the LDLR binding site located on PCSK9^D374Y was postulated by in silico tools.

Soybean- and Lupin-Derived Peptides Inhibit DPP-IV Activity on In Situ Human Intestinal Caco-2 Cells and Ex Vivo Human Serum

Recent investigations have focused on food-derived peptides as novel natural inhibitors of dipeptidyl peptidase IV (DPP-IV), a new target for diabetes. This study aimed to optimize fast, sensitive, and cost-effective DPP-IV assays in situ on human intestinal Caco-2 cells and ex vivo on human serum. Both assays were applied to investigate the inhibitory activity of soy and lupin peptides. The best conditions for in situ DPP-IV activity in Caco-2 cells were obtained using 2-day cells and 50 µM Gly-Pro-AMC. Sitagliptin, used as reference inhibitor, showed a dose-dependent response with a 50% inhibition concentration (IC₅₀) of 0.6 µM. A lower IC₅₀ (0.2 µM) was obtained for sitagliptin on human serum incubated with the substrate for 24 h. Both assays were applied to assess the activity of Lup1 (LTFPGSAED) and Soy1 (IAVPTGVA) on DPP-IV. Lup1 and Soy1 inhibited DPP-IV in situ, with IC₅₀ values of of 207.5 and 223.2 µM, respectively, and maintained their inhibitory activity ex vivo on circulating DPP-IV with a slightly lower potency. These assays can be used to characterize the DPP-IV inhibitory activity of food-derived molecules more accurately than in vitro biochemical tests. This combined approach also considers their effects on the circulating form of DPP-IV, correlated to metabolic diseases.

Maternal serum markers. Estimation of the risk of Down's syndrome: a prospective study

The risk of Down's syndrome pregnancies can be estimated by quantitation of maternal serum markers, namely alpha-fetoprotein, unconjugated estriol and human chorionic gonadotropin (triple test). A prospective study of 2892 pregnant women (median age 33.5 years) is reported. The detection rate of Down's syndrome pregnancies was 80% (confidence intervals 45%-100%) when a risk of 1:380 or greater was considered "screen positive", the false positive rate was 13.3% (confidence intervals 12.0%-14.5%). The importance of the accurate assessment of gestational age and the time of blood sampling are emphasized. Our findings are compared with similar studies performed in other laboratories.

[Variations in ferritin levels in blood during physiological pregnancy]

Iron deficiency anemia is the most frequent haematological pathology in pregnancy. Serum ferritin levels represent the state of iron deposits. Low levels are a sure sign of iron deficiency. At the University of Turin we studied the variations of serum ferritin levels during physiological pregnancy and the sensitivity of routine blood tests with respect to serum ferritin levels. Routine haematological blood values along with ferritin levels were measured in 115 patients throughout pregnancy. The mean serum ferritin level was 56 ng/ml in the first trimester, 27.2 ng/ml in the second and 11.8 ng/ml in the third. The incidences of anemia per trimester was 6.6%, 4.8% and 49% respectively (p less than 0.05, chi squared). Our results show that it is important to evaluate iron deposits early in pregnancy by measuring serum ferritin levels in order to determine the need for iron therapy.

Screening for fetal Down's syndrome with maternal serum markers--an experience in Italy

The effectiveness of maternal serum alpha-fetoprotein, unconjugated oestriol, and human chorionic gonadotrophin in screening for Down's syndrome (DS) was evaluated on 840 women who underwent amniocentesis for fetal karyotype on account of their age. The risk of a DS pregnancy was established using the method of Wald et al. (1988b), which combines the age-specific risk with that indicated by the levels of the three serum markers. In women over 35, at cut-off risk levels of 1:250 and 1:380, the false-positive rate was 24 and 34 per cent, respectively. In all nine cases of DS, the estimated risk was higher than 1:250. The best screening strategy with the lowest false-positive rate was obtained by combining the three serum markers. The results suggest that this kind of screening can be proposed during genetic counselling for women under 35 and older women wishing to avoid the risk of miscarriage induced by amniocentesis.

[TRH stimulation test in the diagnosis of hyperthyreosis]

After a review concerning the present knowledge on the hypothalamic peptide releasing hormones, the response of TSH to intravenous administration of TRH in man (Thyreotrophin Releasing Hormone Stimulation Test) is discussed, with regard to clinical endocrinology. Personal investigations with the TRH test were carried out in 3 groups of conditions correlated with thyroid hyperfunction: 1) suspected hyperthyroidism with equivocal routine tests (9 subjects); 2) autonomous thyroid decompensated adenoma, with or without clinical hyperthyroidism (5 subjects); 3) thyrotoxicosis (Graves' disease) in remission phase after pharmacological or surgical treatment (10 subjects). In these conditions the test provided useful diagnostic information for appropriate therapeutical decisions.

[Association of adult obese-type diabetes and depressive psychosis (clinical cases)]

The conception of a specific association between maturity-onset diabetes and manic-depressive psychosis, on a common basis with diencephalic functional obesity, has been recently taken again in consideration by the psychiatric literature. Investigations on this problem from diabetological point of view have been so far completely lacking, and are proposed with the present study. Symptomatic depressive conditions in diabetes are frequent and should be primarily separated from depressive endogenous psychosis. The pathogenesis of the association between diabetes of the adult-obese type and psychosis might be discussed according to a transactional theoretical model, assuming a positive feed-back mechanism of the two relationships: diabetes-psychosis and psychosis-diabetes. With these criteria, 4 observations of the clinical association were collected out of 274 admissions for diabetes, during 1976. Diabetes is intended as overt diabetes; obesity presented with the stenic picture; psychosis had a monopolar melancholic course. Similar clinical features were characteristic in all cases. The relationship diabetes-psychosis showed no evidence, unless importance should be given to a potential diabetes in 3 cases. On the contrary, the relationship psychosis-diabetes could be demonstrated in the four cases. A psychosomatic scheme connecting the neuro-hormonal correlations to a genetically conditioned exhaustion of the beta-function, is postulated. During melancholic recurrences, diabetes proved to be insulin-dependent and even insulin-resistent in 2 cases. Tricyclic antidepressant theraphy did not modify the metabolic situation.