Dipeptidyl Peptidase IV Inhibitory Peptides from Chickpea Proteins (Cicer arietinum L.): Pharmacokinetics, Molecular Interactions, and Multi-Bioactivities.

Chickpea (Cicer arietinum L.) peptides can inhibit dipeptidyl peptidase IV (DPP-IV), an important type 2 diabetes mellitus therapeutic target. The molecular interactions between the inhibitory peptides and the active site of DPP-IV have not been thoroughly examined, nor have their pharmacokinetic properties. Therefore, the predictions of legumin- and provicilin-derived DPP-IV inhibitory peptides, their molecular interactions with the active site of DPP-IV, and their pharmacokinetic properties were carried out. Ninety-two unique DPP-IV inhibitory peptides were identified. Papain and trypsin were the enzymes with the highest AE (0.0927) and lowest BE (6.8625 × 10-7) values, respectively. Peptide binding energy values ranged from -5.2 to -7.9 kcal/mol. HIS-PHE was the most potent DPP-IV inhibitory peptide and interacts with residues of the active sites S1 (TYR662) and S2 (GLU205/ARG125 (hydrogen bonds: <3.0 Å)), S2 (GLU205/GLU206 (electrostatic interactions: <3.0 Å)), and S2' pocket (PHE357 (hydrophobic interaction: 4.36 Å)). Most peptides showed optimal absorption (76.09%), bioavailability (89.13%), and were non-toxic (97.8%) stable for gastrointestinal digestion (73.9%). Some peptides (60.86%) could also inhibit ACE-I. Chickpea is a source of non-toxic and bioavailable DPP-IV-inhibitory peptides with dual bioactivity. Studies addressing the potential of chickpea peptides as therapeutic or adjunct agents for treating type 2 diabetes are warranted.

Human Coronavirus Cell Receptors Provide Challenging Therapeutic Targets.

Coronaviruses interact with protein or carbohydrate receptors through their spike proteins to infect cells. Even if the known protein receptors for these viruses have no evolutionary relationships, they do share ontological commonalities that the virus might leverage to exacerbate the pathophysiology. ANPEP/CD13, DPP IV/CD26, and ACE2 are the three protein receptors that are known to be exploited by several human coronaviruses. These receptors are moonlighting enzymes involved in several physiological processes such as digestion, metabolism, and blood pressure regulation; moreover, the three proteins are expressed in kidney, intestine, endothelium, and other tissues/cell types. Here, we spot the commonalities between the three enzymes, the physiological functions of the enzymes are outlined, and how blocking either enzyme results in systemic deregulations and multi-organ failures via viral infection or therapeutic interventions is addressed. It can be difficult to pinpoint any coronavirus as the target when creating a medication to fight them, due to the multiple processes that receptors are linked to and their extensive expression.

In vitro characterization of lactic acid bacterial strains isolated from fermented foods with anti-inflammatory and dipeptidyl peptidase-IV inhibition potential.

Probiotics are known to stimulate, modulate, and regulate host immune response by regulating specific sets of genes and improve glucose homeostasis through regulating dipeptidyl peptidase (DPP-IV) activity, but the mechanism behind their protective role is not clearly understood. Therefore, the present study was designed to isolate indigenous lactic acid bacterial (LAB) strains from different fermented food samples, vegetables, and human infant feces exhibiting anti-inflammatory, antioxidant, and DPP-IV inhibitory activity. A total of thirty-six Gram-positive, catalase-negative, and rod-shaped bacteria were isolated and screened for their anti-inflammatory activity using lipopolysaccharide (LPS)-induced inflammation on the murine (RAW264.7) macrophages. Among all, sixteen strains exhibited more than 90% reduction in nitric oxide (NO) production by the LPS-treated RAW264.7 cells. Prioritized strains were characterized for their probiotic attributes as per the DBT-ICMR guidelines and showed desirable probiotic attributes in a species and strain-dependent manner. Accordingly, Lacticaseibacillus rhamnosus LAB3, Levilactobacillus brevis LAB20, Lactiplantibacillus plantarum LAB31, Pediococcus acidilactici LAB8, and Lactiplantibacillus plantarum LAB39 were prioritized. Furthermore, these strains when co-supplemented with LPS and treated on RAW264.7 cells inhibited the mitogen-activated protein kinases (MAPKs), i.e., p38 MAPK, ERK1/2, and SAPK/JNK, cyclooxygenase-2 (COX-2), relative to the LPS-alone-treated macrophages. LAB31 and LAB39 also showed 64 and 95% of DPP-IV inhibitory activity relative to the Lacticaseibacillus rhamnosus GG ATCC 53103, which was used as a reference strain in all the studies. Five prioritized strains ameliorated the LPS-induced inflammation by downregulating the JNK/MAPK pathway and could be employed as an alternative bio-therapeutic strategy in mitigating gut-associated inflammatory conditions. The potential mechanism of action of prioritized LAB strains in preventing the LPS-induced inflammation in RAW 264.7 macrophage cells.

Critical Review for the Production of Antidiabetic Peptides by a Bibliometric Approach.

The current bibliometric review evaluated recent papers that researched dietary protein sources to generate antidiabetic bioactive peptides/hydrolysates for the management of diabetes. Scopus and PubMed databases were searched to extract bibliometric data and, after a systematic four-step process was performed to select the articles, 75 papers were included in this review. The countries of origin of the authors who published the most were China (67%); Ireland (59%); and Spain (37%). The journals that published most articles on the subject were Food Chemistry (n = 12); Food & Function (n = 8); and Food Research International (n = 6). The most used keywords were 'bioactive peptides' (occurrence 28) and 'antidiabetic' (occurrence 10). The most used enzymes were Alcalase® (17%), Trypsin (17%), Pepsin, and Flavourzyme® (15% each). It was found that different sources of protein have been used to generate dipeptidyl peptidase IV (DPP-IV), α-amylase, and α-glucosidase inhibitory peptides. In addition to antidiabetic properties, some articles (n = 30) carried out studies on multifunctional bioactive peptides, and the most cited were reported to have antioxidant and antihypertensive activities (n = 19 and 17, respectively). The present review intended to offer bibliometric data on the most recent research on the production of antidiabetic peptides from dietary proteins to those interested in their obtention to act as hypoglycemic functional ingredients. The studies available in this period, compiled, are not yet enough to point out the best strategies for the production of antidiabetic peptides from food proteins and a more systematic effort in this direction is necessary to allow a future scale-up for the production of these possible functional ingredients.

Crosstalk between incretin hormones, Th17 and Treg cells in inflammatory diseases.

Intestinal epithelial cells constantly crosstalk with the gut microbiota and immune cells of the gut lamina propria. Enteroendocrine cells, secrete hormones, such as incretin hormones, which participate in host physiological events, such as stimulating insulin secretion, satiety, and glucose homeostasis. Interestingly, evidence suggests that the incretin pathway may influence immune cell activation. Consequently, drugs targeting the incretin hormone signaling pathway may ameliorate inflammatory diseases such as inflammatory bowel diseases, cancer, and autoimmune diseases. In this review, we discuss how these hormones may modulate two subsets of CD4 + T cells, the regulatory T cells (Treg)/Th17 axis important for gut homeostasis: thus, preventing the development and progression of inflammatory diseases. We also summarize the main experimental and clinical findings using drugs targeting the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP-1) signaling pathways and their great impact on conditions in which the Treg/Th17 axis is disturbed such as inflammatory diseases and cancer. Understanding the role of incretin stimulation in immune cell activation and function, might contribute to new therapeutic designs for the treatment of inflammatory diseases, autoimmunity, and tumors.

Identification of antidiabetic peptides derived from in silico hydrolysis of three ancient grains: Amaranth, Quinoa and Chia.

The antidiabetic potential of bioactive peptides derived from simulated gastrointestinal digestion (SGID) of proteins present in amaranth quinoa and chia was evaluated using their bioactivity profile and theoretical interaction with DPP-IV and α-glucosidases. In silico SGID generated 52 different fragments with in vitro antidiabetic activity where fragments PW, PF, PPG, PM, SW, IW, SF, PP, PPL, PG, PY, VW and PL scored highly in bioactivity probability, with molecular weights ranging from 172.2 to 325.44 Da; positive bulkiness index and hydrophobicity (except PP and PY) and no toxic properties. Fragments IW and PW presented the lowest free energy values for enzymes DPP-IV, maltase-glucoamylase, pancreatic α-amylase and sucrase-isomaltase (-8.2, -7.5, -7.7 and -7.5 kcal/mol; and -7.8, -7.4, -8.2, -7.4 kcal/mol respectively) We can conclude that proteins from amaranth, quinoa and chia may be a good source of antidiabetic BP and may exert antidiabetic activity through the release of BP after digestion.

Engineering Concanavalin B to Release Bioactive Peptides against Metabolic Syndrome.

Metabolic syndrome is a severe public health issue characterized by multiple metabolic disturbances. Current treatments prescribe a particular drug for each of them, producing multiple side effects. As a first step towards a more integral approach, we applied our recently described methodology to design single proteins, based in the Concanavalin B scaffold (1CNV), that contain several bioactive peptides (BPs), including antioxidant and lipid-lowering activities as well as inhibitors of dipeptidyl peptidase IV (DPPIV) and the angiotensin converting enzyme. Modified Concanavalin (CNV44), the designed protein that showed the best in silico properties, was expressed in high yields in E. coli and purified to homogeneity. After in vitro digestion with gastrointestinal enzymes, all the biological activities tested where higher in CNV44 when compared to the non-modified protein 1CNV, or to other previous reports. The results presented here represent the first in vitro evidence of a modified protein with the potential to treat metabolic syndrome and open the venue for the design of proteins to treat other non-communicable diseases.

In silico Studies on the Interaction Between Bioactive Ligands and DPPIV: Insights on Potential Candidates for the Treatment of type 2 Diabetes Mellitus.

INTRODUCTION: The enzyme called dipeptidyl peptidase IV (DPP-IV) is related to the glycemic control associated with the stimulation of the pancreas to produce insulin. So, its inhibition is a good strategy for the treatment of type 2 diabetes mellitus. METHODS: In this study, we have employed molecular modeling strategies such as CoMFA, molecular docking, molecular dynamics, and binding free energy calculations of a set of DPP-IV inhibitors in order to understand the main characteristics related to the biological activity of these ligands against the enzyme. RESULTS: The models obtained from CoMFA presented significant values of internal (0.768) and external (0.988) validations. Important interactions with some residues, such as Glu205, Tyr666, Arg125, Ser630, Phe357 and Tyr662, were also identified. In addition, calculations of the electronic properties allowed relating the LUMO and HOMO energies with the biological activity of the compounds studied. The results obtained from the molecular dynamics simulations and the SIE calculations (ΔG) indicated that the inhibitor 40 increases the stability of the DPP-IV target. CONCLUSIONS: Therefore, from this study, it is possible to propose molecular modifications of these DPP-IV inhibitors in order to improve their potential to treat type 2 diabetes.

Bestatin and bacitracin inhibit porcine kidney cortex dipeptidyl peptidase IV activity and reduce human melanoma MeWo cell viability.

Bestatin and bacitracin are inhibitors of metallo aminopeptidases and bacterial proteases. However, their effects on other human peptidases, like dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5) are not established. Inhibitors of DPP-IV activity are used for treating type 2 diabetes mellitus, cancers and immune system diseases. Bacitracin and bestatin inhibited porcine membrane-bound DPP-IV (pDPP-IV) activity. Mechanisms were different, i.e. non-competitive with α > 1 (α = 3.9) and Ki value of 75 µM for bestatin, and competitive with Ki value of 630 µM for bacitracin. The binding mode in the tertiary complex enzyme:substrate:bestatin suggested the structural basis of the inhibitory effect and that bestatin is potentially selective for DPP-IV, ineffective vs. S9 family members dipeptidyl peptidase 8/9 and fibroblast activation protein. In the human melanoma MeWo cell line, bestatin and bacitracin inhibited aminopeptidase N (APN) and DPP-IV activities, reduced cell viability and increased DNA fragmentation, suggesting induction of apoptosis. Since bacitracin and bestatin are already marketed drugs, studying in depth the molecular mechanisms underlying their effects on melanoma cells is warranted. Additionally, bestatin emerges as a new lead compound for the development of DPP-IV inhibitors, and a promising dual APN/DPP-IV inhibitor for the treatment of pathologies in which both enzymes are upregulated.

Pharmacological evaluation of Rhazya stricta root extract / Evaluación farmacológica del extracto de raíz de Rhazya stricta

The present study aimed to screen the Rhazya stricta Decne root for its antihyperglycemic and antioxidants potential through invitro assays along with phytochemical and elemental analyses. The crude extract was prepared through maceration and fractionated using solvent-solvent extraction technique. The spectroscopic studies indicated the presence of various phytochemical classes in the extract and its fractions. The antioxidant assays showed notable results along with a good concentration of phenolic and flavonoid contents. Enzyme inhibition assays demonstrated glucose-lowering effects by inhibiting the enzyme activity which could reduce post-prandial blood glucose level. The Dipeptidyl peptidase-IV (DPP-IV) inhibition assay results showed the novel DPP-IV inhibition activity of the plant extract and all fractions showed noteworthy enzyme inhibition and antihyperglycemic activity. Conclusively, the Rhazya stricta root extract displayed its antioxidant and antihyperglycemic potential due to the presence of various classes of phytochemicals and micro-nutrients.

El presente estudio tuvo como objetivo examinar la raíz de Rhazya stricta Decne por su potencial antihiperglicémico y antioxidante a través de ensayos in vitro junto con análisis fitoquímicos y elementales. El extracto crudo se preparó por maceración y se fraccionó usando una técnica de extracción solvente-solvente. Los estudios espectroscópicos indicaron la presencia de varias clases fitoquímicas en el extracto y sus fracciones. Los ensayos antioxidantes mostraron resultados notables junto con una importante concentración de contenido fenólico y flavonoide. Los ensayos de inhibición enzimática demostraron efectos reductores de la glucosa al inhibir la actividad enzimática que podría reducir el nivel de glucosa posprandial en sangre. Los resultados del ensayo de inhibición de Dipeptidyl peptidase-IV (DPP-IV) mostraron la nueva actividad de inhibición de DPP-IV del extracto de la planta y todas las fracciones mostraron una notable inhibición enzimática y actividad antihiperglicémica. En conclusión, el extracto de raíz de Rhazya stricta Decne mostró su potencial antioxidante y antihiperglicémico debido a la presencia de varias clases de fitoquímicos y micronutrientes.

DPPIV/CD26: a tumor suppressor or a marker of malignancy?

Dipeptidyl peptidase IV (DPPIV/CD26) is a multifunctional protein with intrinsic peptidase activity that inactivates or degrades some bioactive peptides. It is the main cellular binding protein for ecto-adenosine deaminase and interacts with extracellular matrix proteins, besides participating in different signaling pathways. Due to these multiple functions, DPPIV/CD26 has been shown to be closely related to the tumor process. It has been reported that the progression of certain types of cancer is accompanied by a decrease in DPPIV/CD26 expression, and studies have shown that the malignant phenotype can be reverted when DPPIV/CD26 expression is induced in these cancer cells, characterizing this protein as a tumor suppressor. On the other hand, DPPIV/CD26 was described as a protein associated with invasion and metastatic spread, characterizing it as a marker of malignancy. Thus, this review explores the roles of DPPIV/CD26 expression in tumor progression in different types of cancer and demonstrates the importance of this protein as a promising therapeutic target and tumor biomarker.

Efecto inhibitorio de un extracto acuoso de las hojas de Allophylus cominia (L) Sw sobre las proteínas tirosina fosfatasa 1B y dipeptidil peptidasa IV / Inhibitory effect of Allophylus cominia (L) Sw leaves aqueous extract on tyrosine phosphatase 1B and dipeptidyl peptidase IV proteins

Introducción: Allophylus cominia (L.) Sw es una planta medicinal cubana usada por la medicina tradicional para el tratamiento de la diabetes, cuyo mecanismo de acción es desconocido. Objetivo: evaluar el efecto del extracto acuoso de hojas de A. cominia (L.) Sw y sus fracciones sobre la proteína tirosina fosfatasa 1B (PTP1B) y dipeptidil peptidasa IV (DPPIV) como diana terapéuticas para el tratamiento de la diabetes tipo 2. Métodos: el extracto acuoso de hojas de A. cominia fue fraccionado sucesivamente con mezclas de solventes orgánicos, incrementando la polaridad, para obtener diez fracciones. El extracto y sus fracciones fueron evaluados para su posible actividad antidiabética sobre diana terapéuticas de diabetes tipo 2: PTP1B y DPPIV. Se realizaron ensayos de inhibición enzimática y la actividad inhibitoria se calculó a partir de los valores de fluorescencia, empleando longitudes de onda de excitación y de emisión de 360 nm y 460 nm respectivamente. Resultados: el extracto acuoso de A. cominia inhibió la actividad enzimática de PTP1B y DPPIV de manera dependiente de la concentración, con valores de CI50 de 0,69 µg/mL y 344,3 µg/mL respectivamente. Varias fracciones se detectaron como potentes inhibidores de PTP1B. Las fracciones más polares AcF9 y AcF10 fueron las más activas, y mostraron valores de CI50 de 4,4 µg/mL y 3,8 µg/mL respectivamente. Las fracciones mostraron una ligera inhibición de DPPIV, y las más activas resultaron AcF6, AcF9 y AcF10, con valores de porcentajes de inhibición de 52,0 por ciento, 39,0 por ciento y 40,0 por ciento respectivamente. Conclusiones: el extracto acuoso de A. cominia y sus fracciones polares (AcF9 y AcF10) tienen propiedades antidiabéticas in vitro y son candidatos promisorios para el desarrollo de nuevos medicamentos con actividad inhibidora de PTP1B y DPPIV para el tratamiento de la diabetes tipo 2(AU)

INTRODUCTION: Allophylus cominia (L.) Sw is a Cuban medicinal plant used by traditional medicine for the treatment of diabetes with unknown mechanisms of action. OBJECTIVE: to evaluate the effect of Allophylus cominia (L.) Sw leaves aqueous extract and its fractions on protein tyrosine phosphatase 1B (PTP1B) and dipeptidyl peptidase IV (DPPIV) enzymatic activity, as therapeutic targets of type 2 diabetes. METHODS: the aqueous extract of A. cominia leaves was successively partitioned with organic solvents mixtures, thus increasing polarity in order to obtain ten fractions. The extract and its fractions were tested for their possible antidiabetic activity on therapeutic targets of type 2 diabetes: PTP1B and DPPIV. The enzymatic inhibition assays were performed and the inhibitory activity was calculated with the fluorescence values using an excitation wavelength of 360 nm and an emission wavelength of 460 nm. RESULTS: the aqueous extract from A. cominia inhibited the enzymatic activity of PTP1B and DPPIV according to the concentration, being IC50 values equal to 0.69 µg/mL and 344.3 µg/mL, respectively. Several fractions were detected as potent PTP1B inhibitors. The most polar fractions AcF9 and AcF10 were more active, showing IC50values of 4.4 µg/mL and 3.8 µg/mL respectively. The fractions showed a slight DPPIV inhibition, being fractions AcF6, AcF9 and AcF10 the most active, exhibiting inhibition percentages of 52.0 percent, 39.0 percent and 40.0 percent respectively. CONCLUSIONS: A. cominia aqueous extract and its polar fractions (AcF9 and AcF10) have antidiabetic properties in vitro and are promissory candidates for development of new drugs with inhibitory activity of PTP1B and DPPIV for type 2 diabetes treatment(AU)

Altered dynamics of a lipid raft associated protein in a kidney model of Fabry disease.

Accumulation of globotriaosylceramide (Gb3) and other neutral glycosphingolipids with galactosyl residues is the hallmark of Fabry disease, a lysosomal storage disorder caused by deficiency of the enzyme alpha-galactosidase A (α-gal A). These lipids are incorporated into the plasma membrane and intracellular membranes, with a preference for lipid rafts. Disruption of raft mediated cell processes is implicated in the pathogenesis of several human diseases, but little is known about the effects of the accumulation of glycosphingolipids on raft dynamics in the context of Fabry disease. Using siRNA technology, we have generated a polarized renal epithelial cell model of Fabry disease in Madin-Darby canine kidney cells. These cells present increased levels of Gb3 and enlarged lysosomes, and progressively accumulate zebra bodies. The polarized delivery of both raft-associated and raft-independent proteins was unaffected by α-gal A knockdown, suggesting that accumulation of Gb3 does not disrupt biosynthetic trafficking pathways. To assess the effect of α-gal A silencing on lipid raft dynamics, we employed number and brightness (N&B) analysis to measure the oligomeric status and mobility of the model glycosylphosphatidylinositol (GPI)-anchored protein GFP-GPI. We observed a significant increase in the oligomeric size of antibody-induced clusters of GFP-GPI at the plasma membrane of α-gal A silenced cells compared with control cells. Our results suggest that the interaction of GFP-GPI with lipid rafts may be altered in the presence of accumulated Gb3. The implications of our results with respect to the pathogenesis of Fabry disease are discussed.

Higher insulin and glucagon-like peptide-1 (GLP-1) levels in healthy, young South Asians as compared to Caucasians during an oral glucose tolerance test.

OBJECTIVE: Higher insulin levels during an oral glucose test (OGTT) have been shown in South Asians. We aimed to investigate if this increased insulin response causes reactive hypoglycemia later on, and if an increased glucagon-like-peptide-1 (GLP-1) response, which could contribute to the hyperinsulinemia, is present in this ethnic group. METHODS: A prolonged, 6-h, 75-g OGTT was performed in healthy, young Caucasian (n=10) and South Asian (n=8) men. The glucose, insulin and GLP-1 response was measured and indices of insulin sensitivity and beta-cell activity were calculated. RESULTS: Age (Caucasians (CAU) 21.5±0.7 years vs South Asians (SA) 21.4±0.7 years (mean±SEM)) and body mass index (CAU 22.7±0.7 kg/m(2) vs SA 22.1±0.8 kg/m(2)) were comparable between the two groups. South Asian men were more insulin resistant, as indicated by a comparable glucose but significantly higher insulin response, and a significantly lower Matsuda index (CAU 8.7(8.6) vs SA 3.2(19.2), median(IQR)). South Asians showed a higher GLP-1 response, as reflected by a higher area under the curve for GLP-1 (CAU 851±99.8 mmol/l vs SA 1235±155.0 mmol/L). During the whole 6-h period, no reactive hypoglycemia was observed. CONCLUSION: Healthy, young South Asian men have higher insulin levels during an OGTT as compared to Caucasians. This does not, however, lead to reactive hypoglycemia. The hyperinsulinemia is accompanied by increased levels of GLP-1. Whether this is an adaptive response to facilitate hyperinsulinemia to overcome insulin resistance or reflects a GLP-1 resistant state has yet to be elucidated.